Superhydrophobic Textiles: Review of Theoretical
Definitions, Fabrication and Functional Evaluation
Sohyun Park1, Jooyoun Kim, PhD2, Chung Hee Park, PhD1
1
Seoul National University, Seoul KOREA
2
Kansas State University, Department of Apparel, Textiles, and Interior Design, Manhattan, KS UNITED STATES
Correspondence to:
Chung Hee Park email: [email protected]
ABSTRACT
Engineering of superhydrophobic textile surfaces has
gained significant scientific and industrial interest for
its potential applications in outdoor wear and
protective textiles, resulting in many publications
especially on theoretical models and fabrication
methods. In this review, progress in theoretical
definitions to explain the wetting behavior and
realization techniques for superhydrophobic textile
surfaces is discussed. Firstly, theoretical models from
Young, Wenzel, and Cassie-Baxter to the more recent
re-entrant angle model are overviewed to understand
the design strategy for superhydrophobic surfaces.
Secondly, major surface manipulation techniques to
produce superhydrophobic textiles were reviewed
for: modification of surface energy, addition of
surface roughness by depositing or growing
nanoparticles either in spherical form or in high
aspect ratio, etching by plasma or caustic chemicals.
Particular attention is paid to evaluation methods to
measure the level of hydrophobicity for
superhydrophobic textile surfaces, as a limitation of
static water contact angle (WCA) on differentiating
superhydrophobic surfaces has been reported
elsewhere. The challenges in application of
superhydrophobic textiles to clothing materials in
terms of comfort properties and durability are
discussed with the suggestion of further research
opportunities to expand the application.
INTRODUCTION
Recently, there has been active research in
biomimetic technology for developing highly
functional materials that mimic nature. In
superhydrophobic
research,
superhydrophobic
surfaces refer to surfaces with excellent water
repellency with a water contact angle (WCA)
exceeding 150° and low contact angle hysteresis
(CAH) of less than 10°. The most well-known
example is the development of superhydrophobic
self-cleaning materials that mimic lotus leaves. The
lotus-leaf, which is one of the best known natural
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superhydrophobic surfaces, effectively removes
impurities, such as mud, with water. It was found that
this is because nano-level hydrophobic wax crystals
on top of micro-level bumps on lotus-leaf surfaces
come together to have strong superhydrophobic
attributes [1]. At such surfaces, dirt and soils are
loosely attached, and a rolling water drop can easily
attach the loosely bonded substances, removing them
from the surface, giving self-cleaning effects. Due to
this, the phenomenon of self-cleaning resulting from
a superhydrophobic surface that does not become wet
is called the lotus effect. This surface characteristic is
applicable in industries for oil repellency, anticorrosion, anti-fogging/frosting, anti-bioadhesion,
and water-oil separation. Because of this, there has
been active research for the past several decades on
various methods and materials that propose
superhydrophobic and ultra-oil repellency that
control wettability for water, oil, and non-polar
liquids through the chemical makeup of solid
surfaces and designing geometrical surface structures
[2-7].
In the past few years, various studies have been
focused on the textile applications of such
superhydrophobic/superoleophobic
characteristics,
and textile materials with large WCA and selfcleaning effects have been commercialized [8].
Superhydrophobic textiles can grant not only
excellent water repellency and oil resistance, but also
active self-cleaning performance, and thus they can
be used as high protective clothing textiles and
functional
outdoor
clothing
materials
[2].
Furthermore, it can reduce the number of launderings
thanks to the self-cleaning performance. When the
number of launderings is reduced, the performance of
the highly functional textiles can be maintained for
long times and can lead to the development of
environment-friendly materials that can reduce the
use of resources and energy needed for laundry.
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Research on superhydrophobic textiles for clothes
started relatively later than other fields. Despite
reports on various developments, the configuration
methods and evaluation methods of other fields are
being applied as in textiles, and there are tendencies
to focus only on the configuration of high
superhydrophobicity without considering the unique
features of required performance of clothing textiles.
Clothing materials are very closely related to the
safety and health of people. Therefore, close studies
on the effects of superhydrophobic textiles such as
the safety of used materials, environmental
responsibility of processing methods, and the
functional suitability or durability of developed
materials are necessary. In particular, by reviewing
the studies on the theoretical development and
fabrication
techniques
for
developing
superhydrophobic
surfaces,
adequate
design
strategies for superhydrophobic textile surfaces will
be able to be suggested. Thus this review is intended
to overview the progress of theories and engineering
techniques to learn about the challenges of
superhydrophobic textile applications and to explore
the research opportunities to realize practical
applications. Also, discussions on evaluation methods
would give hint on relevant assessment methods that
measure the representative characteristics for the
applied uses.
perfluorocarbon ( , 5~10 dyne/cm), if there’s no
roughness developed at the surface, static WCA stops
short with superhydrophobicity (WCA was 105-118°)
[10].
(1)
FIGURE 1. Young’s model for static contact angle in relation with
interfacial tensions of solid/liquid/vapor phases. ( : solid-vapor
interfacial tension,
: water-solid interfacial tension,
watervapor interfacial tension).
Wenzel & Cassie-Baxter Models
Most solid surfaces in daily life have roughened
surfaces and violate the assumptions of Young’s
model [9]. Therefore, there are limitations in
explaining the surface wettability through Young’s
equation. According to the study of Wenzel [11] and
Cassie-Baxter [12], it explains that on surfaces with
roughened areas, counting both surface free energy
and surface roughness as critical factors for
wettability. The equations of Wenzel and CassieBaxter’s theory were compared in Table I.
MODELS FOR WETTING THEORY
Important theories for explaining surface wettability
include Young’s model, which shows the thermaldynamic equilibrium relations of interface energy of
surface and water drops on flat surfaces, and
Wenzel’s and Cassie-Baxter’s model that explains the
wettability of roughened surfaces.
Wenzel [11] assumed complete contact of a liquid
drop on a solid surface and stated that the contact
angle (ƟW) on the surface is proportional to the
contact angle (Ɵe) on flat surfaces and surface
roughness factor (r). At this time, the surface
roughness factor (r) was displayed as the ratio of the
surface area in contact with liquid to the projected
surface area [11]. In the Wenzel model, the liquid
drop is in complete contact with the solid surface so
(r) is always larger than one. Thus, in the case of
hydrophobic surfaces with low surface free energy
(Ɵe>90), it is explained that as the contact area of the
surface and liquid grows, the contact angle also rises.
The Cassie-Baxter model [12] assumed the
heterogeneous contact where the liquid is not
completely in contact with the solid surface, but is
simultaneously in contact with the trapped air pocket
in surface bumps. At this time, the solid fraction of
contact is defined by the contact area proportion of
the surface with the liquid droplet compared to the
overall projection area. In this model, the apparent
contact angle (ƟCB) is defined as the sum of the
Young’s Model
Young’s equation assumes that the surface is smooth
and explains wettability of liquid drops with the
relationship of static contact angle, interfacial tension
between solid and vapor phases, and interfacial
tension between liquid and vapor phases (Eq. (1)) [9].
At this time, surface wettability is determined by the
chemical makeup of the solid; at an equilibrium state
where a certain liquid drop is in contact with solid, a
solid phase with low surface free energy ( ) would
give large interfacial tension (
of the solid
surface and liquid drop, and large static contact angle
of the liquid phase through Young’s equation.
Therefore, for the processing of superhydrophobic
textiles, the surface free energy of solids is
commonly lowered using water repellant agents.
However, even though the surface is treated with very
low surface free energy material, such as C9
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contribution of the solid surface and air contact, and
explains that when the contact area of the liquid and
air is large, the contact angle increases. The
implication of Cassie-Baxter’s research is that in
order to obtain superhydrophobic surfaces, there are
limitations in using the single method that reduces
surface free energy, and it is advantageous to
implement small-scale surface roughness to enlarge
the contact area between liquid and air.
TABLE I.
As a natural substance with superhydrophobic and
self-cleaning performance, lotus leaves and insect
wings are made up of substances with low surface
free energy; it has also been reported that they have
micro/nano-scale binary structure [1]. Since then,
there have been many studies on developing
superhydrophobic surfaces with dual-scale surface
roughness that mimics their surface structure [8, 1417]. In such research, nano particles were
implemented to artificially change the surface free
energy or design the surface roughness by methods
such as nano implants or lithography, and the surface
with added roughness was analyzed to be superior in
achieving superhydrophobicity [18-23]. When Cheng
et al., [20] removed all of the nano bumps in dried
lotus leaves, WCA dropped from 142° to 126°, and
the importance of nano-scale roughness on surfaces
was validated as to improve superhydrophobicity and
self-cleaning effects. Patankar [18, 19] made a
paraffin wax structure with dual scale roughness to
confirm that binary structures contributed greatly in
enhancing hydrophobicity. In the study, the size ratio
of micro and nano-scale protrusions and the distance
between the protrusions were analyzed to have an
impact on hydrophobicity and self-cleaning effects.
Similar to this, Bhushan & Jung [21] produced a
superhydrophobic surface adjusting the diameter,
height, and distance of bumps and reported that the
column distance, by influencing the shut air pocket,
has a great effect on water drops either becoming
pinned or unwet at the surface, stating that
superhydrophobicity can be enhanced by adjusting
the distance of rough structures. There are a number
of other studies that provide empirical data for the
development of superhydrophobic surfaces. When
summing these up, it is evident that the size ratio of
micro and nano-scale roughness structures,
perpendicular and horizontal proportions of surface
protrusions, and their geometrical shapes affect
superhydrophobicity [15-25].
Wenzel and Cassie-Baxter model.
Figure 2 shows the relationship of the water contact
angle (Ɵflat) on surfaces without roughness and
contact angle (Ɵrough) in surfaces with roughness. The
slope can be determined by the contact area surface
fraction (Φs) and the surface roughness factor (r). The
transformation from the Wenzel state to the CassieBaxter state can be checked by the contact point of
the two lines through the graph, and such
transformation can be induced through control of
surface structure [13].
FIGURE 3. Superhydrophobic difference according to micro/nanoscale surface roughness of HDPE surfaces [22].
FIGURE 2. Wenzel and Cassie-Baxter models in relation to the
surface roughness and static contact angle.
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Re-Entrant Angle Model
The robust superhydrophobic surface displays
repellency not only for water, but also for liquid with
lower surface tension (under 30 dyne/cm).
Furthermore, a superoleophobic surface is defined to
have static contact angles greater than 150° with
organic liquids such as alkanes, like octane, which
have much lower surface tensions than water [24].
Such highly-repellent surfaces would have resistance
against various oily solvents and polluted water,
having a broader range of application in separation
materials, fluid transport, fingerprint resistant
surfaces, self-cleaning textiles, protective clothing,
etc. To achieve a superoleophobic surface, the
surface free energy of the solid must have lower
surface tension than oily solvents and the geometrical
structure of micro/nano-scale roughness at the
surface needs to be optimized [6, 24, 25]. In
particular, because there are limitations in modifying
the surface free energy of the solid surface to be
lower than the surface tension of the oily solvent,
there have been efforts to fabricate superoleophobic
surfaces by designing the optimal geometrical
structure of the surface roughness. Tuteja et al., [6]
theoretically explained the conditions for oilrepelling surfaces with the same surface free energy
and different surface structures (Figure 4). When the
surface protrusion’s geometric angle (ψ) is larger
than the contact angle θ that is made by an interface
between the liquid and solid protrusion (Figure 4a),
the liquid’s re-entrant contact area goes downward
and becomes wet as it goes into the Wenzel state. On
the other hand, when ψ becomes smaller than θ
(Figure 4b), the contact area of the liquid does not
make progress and is maintained to go into the
Cassie-Baxter state. There have been many studies
that claim that superoleophobic surfaces can be
effectively configured by adjusting the micro/nanoscale protrusions or roughness to become the ‘reentrant structure’ through studies related to
superoleophobicity [26-28].
FIGURE 4. Effects of other surface structures of the same surface
free
energy
on
the
solid-liquid-vapor
interface
(a)superhydrophobic, (b)superoleophobicity [6].
Dynamic Characteristics of Water-Solid Interface
Superhydrophobic surfaces have various applicable
features such as self-cleaning, oleophobicity, anticorrosion, drag reduction, non-adhesion, low surface
tension, prevention of snow piling, etc. The criteria
for
distinguishing
superhydrophobic
surface
characteristic is not only high static contact angle
(>150°), but also dynamic contact angle or rolling off
angle [29]. In the Cassie-Baxter state, due to the
trapped air between the protrusions or rough
structures, the adhesion between the solid surface and
water is small, thus the interface of the water and
solid separates easily and rolls off. In the Wenzel
state, the contact area of the solid surface and water is
large and so is the amount of energy to separate the
water from solid surface. Therefore, at this state it
does not roll off, but the water droplet remains on the
fabric surface making it easy to permeate. This “rolloff” phenomenon can be measured through the CAH,
sliding angle (SA), and shedding angle. The surface
that shows low dynamic contact angle represents the
high level of hydrophobicity and the self-cleaning
effects can appear [1, 30].
Until now, in order to configure oleophobicity in the
textile sector, fluorinated compounds with low
surface free energy were often used, but in order to
configure superoleophobicity, multi-faceted analysis
and research on both surface free energy and surface
roughness design are needed. Also, there are many
limitations in the approach that controls the
geometrical shape of rough structures in textile
surfaces.
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The self-cleaning effect, which is a representative
feature of superhydrophobic surfaces, is the effect of
pollutants, such as dust, on the surface attaching to
water rolling off and thus being removed [30].
Barthlott & Neinhuis [1], who studied the effects of
superhydrophobic self-cleaning effects of various
types of lotus leaves, analyzed the impact factors on
self-cleaning effects according to the pollutant
particle size and rain intensity. When the pollutant
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particle is larger than the micro-level protrusion in
the solid surface, it is placed on the upper part of the
protrusion resulting in the contact area between the
solid surface and particle being very small and thus
having very low adsorption energy. At this time, the
water rolling off from the surface, gaining the
adsorption energy, attaches to the pollutant. In order
for the pollutant and water to separate again, a force
stronger than the adhesion force between them is
necessary.
FIGURE 5. Effects of solid surface bumps and self-cleaning
effects [8] (a) self-cleaning of flat surfaces, (b) self-cleaning of
roughened surfaces.
Upon examining the self-cleaning effects according
to the strength of artificial rain, water drops with very
low kinetic energy, such as fog or dew, were found to
have considerably lower self-cleaning effects
compared to regular rainfall [1]. Because the kinetic
energy of water drops that fall from a certain height
gives elastic deformation to surface protrusions and
dust, the kinetic energy of raindrops is advantageous
in adsorption of dirt. Fog or sprinkles with low
kinetic energy cannot give such deformation, thus
having low self-cleaning effects. Figure 5 shows the
self-cleaning effects from flat and rough surfaces.
Self-cleaning effects are manifested when the
pollutant particle has a stronger adhesion force with
water than its coherence to the solid surface.
ENGINEERING
TECHNIQUES
FOR
SUPERHYDROPHOBIC TEXTILES
Many superhydrophobic textiles with a WCA over
160° and low CAH have been introduced with
commercialization efforts in the outdoor wear
industry. Early development of superhydrophobic
textiles was mostly made by coating the textile
surface with a low surface free energy material to
lower the surface free energy. Recently, with the
emphasis on the importance of micro/nano binary
structures, attempts to grant nano-scale roughness on
the micro-rough fiber surface were attempted. To
achieve this, textile surfaces were coated with nanoparticles or processed so that nano structures were
formed by self-assembly or by surface etching, while
adding post-processing to lower surface free energy
have been made. The following are representative
superhydrophobic processing technologies.
Therefore,
in
order
to
configure
the
superhydrophobic
surface
with
self-cleaning
functions, the surface energy must be lowered and the
surface roughness enlarged to weaken the cohesion of
the pollutant with the solid surface, while
maintaining the water droplet form so that it rolls off
easily [8]. However, when the pollutant is chemically
superhydrophobic, the adhesion force with the water
drop would be low, thus having little self-cleaning
effect. Studies on the self-cleaning effects of
superhydrophobic surfaces until now have focused on
revealing the self-cleaning process. However,
additional discussions are also necessary on various
factors that affect the self-cleaning effect such as the
size and surface structure of pollutant particles,
chemical attributes of pollutant particles, and the
quantity of water that is rolled off and its falling
distance.
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Modification of Surface Free Energy
The method for lowering surface free energy is a
basic control for superhydrophobic characteristics
and is a very effective approach for generating
hydrophobicity easily and at low costs. Textiles use
filament groups made up of yarn and form various
surface structures according to the yarn’s texturizing
processing, weave pattern, density, etc. Textiles form
a unique surface roughness by the filament groups
and yarns, while adjusting the yarn size and number
of filament fibers in a yarn can adjust the roughness
at the submicron-scale. As a method for granting
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surface roughness using yarn and filament, Gao &
McCarthy [31] used a polyethylene terephthalate
fabric weaved with 2 μm filaments for dip-pad-dry
coatings using siloxane water-repellants and the
resulting textile surface showed a WCA of 170° and
CAH of under 5°. Compared to general specimens,
the number of trapped air pockets in the
microfilament was much larger, thus water was able
to easily roll off, validating their claim that it was
possible to configure superhydrophobic textiles using
micro fibers without nano-scale roughness [31].
broadened its range of use as it was expected to have
oil resistance and soiling resistance. However, as it
was found that perfluorooctanoic acid (PFOA) can be
potentially cancer-causing and hazardous to the body
in the decomposition process of C8 fluorocarbon
compounds, there have been restrictions on the use of
C8 fluorocarbon processing agents [34].
ENGINEERING TECHNIQUES BY NANOSCALE
SURFACE
ROUGHNESS
STRUCTURING
Superhydrophobic and superoleophobic processing
are developing from lowering the surface free energy
of fibers to designing micro/nano-scale binary
structure surfaces to reduce the contact area of the
surface and liquid droplet, using nanoparticles such
as silica, TiO2, CNT, ZnO, etc., in various ways.
Surface Roughness Formed by Spherical Particles
Zhao [38] used the layer by layer (LBL) assembly
method on cotton fabrics to give roughness using
polyelectrolyte/silica nanoparticle multilayers and
post-treating with fluoroalkylsilane to develop
superhydrophobic textiles with a sliding angle (SA)
of 10° even after ten washes. Wu et al., [39] attached
nano particles on cotton, PET, and silk fabrics by dip
coating in toluene solution with silica nanoparticles
containing long hydrophobic alkyl side-chains to
develop superhydrophobic fabrics with less than a
10° shedding angle. The modified fabric was verified
to maintain hydrophobicity even after 200 abrasions
and washes. This fabrication method was claimed to
be a practical method for the commercialization of
superhydrophobic textiles [39]. Ramaratnam et al.,
[40] and Xue et al., [41] chemically combined silica
nanoparticles with a fabric surface to create
superhydrophobic textiles. This method exhibited
excellent adhesion of silica nanoparticles onto a
fabric substrate. Athauda & Ozer [42] attached
different sized silica nanoparticles (7~40 nm) on the
1st and 2nd layers and developed superhydrophobic
fabrics with a hierarchical binary roughness structure.
FIGURE 6. Effects of yarn that make up fabrics on wettability [31].
(a) 1 mm scale woven bundles of 40 ㎛ fibers. (b) 50 ㎛ scale
woven bundles of 2 ㎛ fibers.
Due to the unique surface structure of textiles, it is
possible to grant highly hydrophobic properties with
water-repellent processing agents only. Various
water-repellant processes have been introduced since
the mid-20th century. Water-repellent/oil-repellent
agents can be categorized as pyridine, silicone, and
fluorocarbon compound types, and, depending on the
chemical composition, the surface free energy of
treated fabrics changes and provides wetting
resistance against water and/or oil. Among the
repellent agents, silicone and fluorocarbon types are
most commonly used. Silicone or siloxane types have
–O-Si-O- backbones with alkyl groups oriented to the
surface, giving hydrophobicity. The processed fabric
surface has a surface free energy of about 20 dyne/cm
[32, 33], thus obtaining water repellency.
Fluorocarbon
compounds
are
normally
perfluoroalkylacrylate copolymers with forms that
are suitable for fibers as compounds containing
perfluoro alkyl groups. As the fluorine containing
ester becomes arranged vertically on the fiber surface,
the surface free energy becomes lower and,
depending on the orientation and distribution of the
perfluoroalkyl groups, it obtains surface free energy
of about 5-20 dyne/cm [32, 33]. Fluorocarbon type
water-repellent agents often show repellency for not
only water, but also oil and oily solvents. It has thus
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In developing superhydrophobic textile fabrics, TiO2
nano aggregates were also used to create a binary
roughness on the fabric surface by a sol-gel method
with post treatment using stearic acid and
1H,1H,2H,2H-perfluorodecyltrichlorosilane (PFTDS)
to lower surface energy. The resulting surface showed
a high WCA of 160°. Furthermore, TiO2
crystallization and aggregation exhibited UV
blocking abilities by scattering light, thus showing
the possibility of developing multi-functional fabrics
[43]. In another study, ZnO/SiO2 particles were made
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with core/shell structures on a PET fabric to give
superhydrophobicity with a WCA of 160°. Since ZnO
can decompose organic materials when exposed to
UV, there are concerns that durability of the ZnO
treated fabric itself and the repellent coating would
also be degraded in direct sunlight. Accordingly, ZnO
nanoparticles with SiO2 could not execute photolysis
on the repellent agent hexadecyltrimethhoxysilane
(HDTMS), thus the treated fabric maintained
hydrophobic functionality under direct sunlight
without degrading the coating agent [44].
and high WCA was developed by attaching multiwall CNT (MWCNT) using simple and economic
methods such as coating or dipping. Among them, a
method developed by Li et al., [46] exhibited strong
chemical adhesion with fabrics with a high WCA of
over 145°, even when the treated fabric was
immersed in acidic solutions of pH 2-12. Shim [47]
proposed a processing method that can apply CNT on
fabrics simple and efficiently, where CNT in a
repellent agent was deposited on to PET fabrics and
gained a WCA of over 160° and shedding angle of
less than 10°. However, it did not reach a level that
controlled the surface arrangement of CNT and
therefore could not develop the surface roughness
using the aspect ratio of CNT. Shateri-Khaliabad &
Yazdanshenas [50] proposed a superhydrophobic
fabric with 7° shedding angle and 163° WCA by
dipping the fabric in oxidized graphene dispersed in a
solvent and hydrophobized. Graphene is a
hydrophobic substance and specimens treated only
with graphene showed hydrophobicity with a WCA
of 143°; the treated fabric can also be used as an
electrical conductive material.
CNT and graphene are materials that are receiving a
great deal of attention due to large surface area, high
durability, high elasticity, and excellent thermal
properties. Also, graphene’s high mechanical strength
as well as transparency and flexibility draw particular
industrial attention. Due to the diverse features of
nano carbon particles, it is expected that
superhydrophobic textiles made with this would have
mutiple functions for a broad range of applications.
In-depth research utilizing this carbon material is
expected as it has high industrial potential in various
sectors such as the clothing, bio-medical, and
electronic sectors.
FIGURE 7. Surface roughness formed by spherical particles (a)
Micro/nano-scale roughening formed with different sized
nanoparticles [42], (b) ZnO/SiO2 nanoparticle coating process on
PET fabrics(left), UV durability of ZnO/SiO2 nanoparticle coating
fabrics(right) [44].
Surface Roughness Formed By Pillar Type
Particles
Instead of using spherical forms of nanoparticles,
utilization of nanoparticles with high aspect ratios,
such as carbon nanotubes (CNT) and nanofilament
type graphene, was also introduced. In a number of
studies that developed superhydrophobic textiles
using
CNT
as
nanoparticles
[45-50],
superhydrophobic fabrics with CAH of less than 5°
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Zimmermann et al., [51] used a method for growing
silicone nano-filaments by chemical vapor deposition
on textiles such as cotton, wool, and polyester to
design silicone hairs as nano-scale roughness on top
of micro-rough fibers to have binary surface
roughness like lotus leaves. As a result,
superhydrophobic polyester textiles with excellent
abrasion resistance were developed with an SH of 2°;
even after abrading 1,000 times, the SH remained at
25° [51].
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FIGURE 9. SiO2 Nanoparticle and a ZnO Nanobar scheme on
fabrics [53]. (a) SiO2 nanoparticles (b) ZnO nanorods
Surface Etching
Many reports were made on etching the fiber surface
to form nano roughening, followed by grafting or
physically/chemically attaching compounds with low
surface energy to develop superhydrophobic textiles
[54-72]. When treating with UV-laser or plasma,
chemical bonds of treated surfaces are broken
forming radical groups, reactors, etc., resulting in
etching and grafting or physical/chemical deposition.
In particular, plasma treatment can adjust hydrophilic
to hydrophobic wettability according to the types and
treating conditions of injected gases, such as oxygen,
argon, helium, and fluorine [55, 60]. As this
technique can be applied to most polymeric materials,
it is being actively used for various attempts in the
textile sector [54, 56, 58, 61, 62, 66, 68, 71].
FIGURE 8. Surface roughness formed by pillar type particles (a)
PBA-g-CNT treated fabric surface SEM image and water contact
[45]. (b) Silicon nano-filament-treated fabric surface SEM image
[51].
ZnO as a nanorod was also utilized to design a binary
roughness structure on a cotton fabric using a sol-gel
method, and n-dodecyltrimethoxysilane (DTMS) was
treated afterwards to lower the surface free energy
[52]. This processing technique costs less than other
methods, producing a superhydrophobic fabric
surface with a WCA of over 161° [52]. Xu & Cai
proposed 161° WCA superhydrophobic cotton fabrics
by coating ZnO crystals on cotton fabrics and then
coating the nanorod developed in a vertical direction
with hydrophobic materials. Xu et al., also examined
and reported in another study the effects of particle
shape of ZnO nanorod and spherical SiO2
nanoparticles on superhydrophobicity [53]. The rolloff angle was influenced by the shape of nanostructure at the surface, giving smaller values when
the surface was treated with ZnO nanorods. However,
there was no significant difference in static WCA
made by the shape of nanoparticles. This
phenomenon was explained by the fact that more air
gap is maintained between the nanorod structures
than the spherical forms, making the adsorption of
water drops on the solid surface more difficult and
thus making water drops roll-off more easily.
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Most studies related to superhydrophobic textiles
using plasma treatment often use this technique to
make a thin layer of chemical coating with
hydrophobic compounds [55]. These applications
include microwave plasma to graft oleic acid on
cotton fabrics producing superhydrophobic surfaces
with a WCA of over 150°, normal pressure plasma
treatment to polymerize hexamethyldisiloxane
(HMDSO) on cotton fabrics to produce a fabric
showing a WCA of over 140°, and received scores
exceeding 90 in the AATCC Spray test, as well as 50
grade after five washes [68]. SF6 RF plasma
treatment was also utilized on cotton, silk, and PET
fabrics to produce hydrophobic surfaces with a WCA
between 130-150° [56]. Fluorine compounds are one
of the most used in plasma treatment to produce
superhydrophobic textiles [58],[64]; in a study by
Huang et al., [73] a superhydrophobic surface was
obtained through PTFE plasma sputter coating on silk
fabrics with 152° WCA and 5° CAH.
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Studies related to plasma treatment showed
comparable moisture absorption and vapor
permeability of treated fabrics as untreated ones,
concluding that plasma treatment only affects the
fabric surface with no significant impact on intrinsic
bulk properties [55, 64, 74].
FIGURE 11. AFM image of polyester fiber surface with nano-scale
roughness. (a) made by UV laser treating [65]. (b) made by air
plasma treating polyester fiber surface, (b) plasma etched polyester
fiber[77].
FIGURE 10. AATCC spray test results on HMDSO plasma treated
cotton fabrics [68]. (a)Non-treated cotton fabric, (b) HMDSO
plasma treated cotton fabric (t4c2).
Meanwhile, studies with respect to the optimization
of plasma treatment conditions to grant nano-scale
surface etching on fiber surfaces have been reported
[75-78]. Atomic Force Microscopy (AFM) was often
used; Poletti et al.,[77] used AFM to measure
changes of the surface area and surface roughness
according to the type of injected gas by summarizing
the results of treating air, He, Ar, SF6, CF4 gases with
various pressures and voltages on polyester fabrics
and compared the etching effects. In another study, a
processing method to form nano-scale wrinkles by
UV laser was proposed to transform hydrophobic
materials with high water and oil resistant
performance [78]. By treating with CF4, H2, and He
gases on cotton fabrics at atmospheric pressure, the
fabric surface turned superhydrophobic where a
water drop does not adhere to the specimen surface
but rather bounces off [63, 65]. Studies that combined
surface roughness with low surface energy include
the work of Twardowski et al., [79] that used argon
plasma and HMDSO to fabricate superhydrophobic
polyester fibers with 150° WCA and the work of
Hodak et al., [65] that used RF plasma to etch and
polymerize fluorocarbon compound on silk surfaces
with a WCA of 140°.
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
FIGURE 12. Selected time sequence images of water droplet
falling on (a) superhydrophobically treated gold film, (b) clean Si
wafer, (c) superhydrophobically treated cotton, and (d) untreated
cotton. All panels are at 2ms intervals, except the ones with dots
between panels. One dot between panels indicates a 4 ms interval.
Two dots are at 6 ms intervals [63].
Etching with a plasma technique gives nano-scale
roughness on fiber surfaces, being an effective
method for engineering surface roughness. In the
materials sector, many research results that evenly
form nano-pillars of high aspect ratios with plasma
etching have been made. Ko et al., [80] used oxygen
plasma etching and HMDSO plasma enhanced
chemical vapor deposition (PECVD) on carbon fibers
to make a surface structure with nano hair in an
9
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aspect ratio of up to 37. They observed the
condensation of water drops on fiber surfaces in
saturated water vapor environments at 2℃ and water
vapor pressure of 5.2 Torr, respectively, and reported
that as the aspect ratio of nano-pillar grows,
superhydrophobicity can be more effectively
displayed. Shin et al., [74] used oxygen plasma
etching on polyester nonwovens to create uniform
nanohair structures. Treatment conditions for
maximizing the linearity of plasma action are
important for etching nano-pillars or hairs that are
dense and have large aspect ratios; it can be adjusted
by gas type, gas flux, in chamber pressure, voltage,
and treatment time. For superhydrophobic textiles,
there are few studies that define the plasma process
parameters to form uniform and dense nano-pillars or
hair on textile surfaces. Further research on
engineering parameters is expected for developing
superhydrophobic textiles using plasma etching.
Meanwhile, as an example of fiber surface etching
through alkali hydrolysis, Mazrouei-Sebdani &
Knoddami [81] produced superhydrophobic fabrics
with less than 10° SHA through forming roughness
by alkali etching and water-repellant treatment by
fluorocarbons.
the intrinsically hydrophobic polyacrylonitrile (PAN)
fiber to make it hydrophilic, then electrospun
hydrophobic PAN on top of it to develop a two layer
nano-web with asymmetric wettability, one of whose
surface was hydrophilic and one having a WCA of
over 150° (Figure 14). Similarly, Thorvaldsson et al.,
[84] electrospun cellulose acetate on top of microsized lyocell filaments to produce a fabric with
asymmetric wettability. The electrospun web, when
made with low surface energy polymers, exhibited
superhydrophobic characteristics without adding
extra geometrical roughness structures on to the
nanoweb [85]. Wang et al., [86] used fluorinated
polyurethane with dispersed SiO2 nanoparticles to
make an electrospun nanoweb with additional
roughness contributed by nanoparticles, and reported
a high CA for oil-based solvents. Particularly, the
thickness of nanofibers and the porosity (with
distance between fibers) was reported to be a major
determinant factor influencing not only water
repellency but also oil repellency [87]. In the study
by Miyauchi et al., [88], electrospun polystyrene was
made by mimicking silver ragwort leaf to form a
micro-scale web roughness and nano-scale wrinkles
by adjusting the volatility of solvents in preparing
superhydrophobic webs.
FIGURE 13. E-SEM image of plasma etching and HMDSO
coating treated carbon fiber [80]. (a) pristine, (b) 15 min plasmatreated and 30 s hydrophobic film-coated and (c) 60 min plasmatreated and 30 s hydrophobic film-coated surfaces (Scale bars are
50 nm). (d–f) Schematics regarding the condensation of water with
respect to the aspect ratio of nanostructures formed on the CFs.
FIGURE 14 Solvent-friendly nano web showing
superhydrophobic and superhydrophilic attributes [83].
Electrospinning
Another method for creating nano-scale roughness
for superhydrophobicity is using nanofibers through
electrospinning. Nano-webs that have nanofibers
produced through electrospinning are made up of
fibers and pores, with a surface with nano-scale
surface roughening [82]. Lim et al., [83] heat-treated
COMPARISON
OF
ENGINEERING
TECHNIQUES FOR SUPERHYDROPHOBIC
TEXTILES
When summing up studies related to development of
superhydrophobic textiles, the traditional method of
coating water-repellant processing agents for textiles
has been put aside, and in its place, various methods
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
10
both
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that
implement
nano-scale
roughness
for
superhydrophobic configuration have been reported.
The benefits and disadvantages of the various
approaches for using superhydrophobic textiles for
clothing were compared.
The textile is made up of yarns composed of several
strands of micro-scale filaments that contribute to the
micro-scale surface roughness. By adding nano-scale
roughness on the textile surface, a micro/nano-scale
binary structure is obtained where the fiber aids in
creating the superhydrophobic surface. Thus, if
nanoparticles are well attached chemically/physically
to the fiber surface, a relatively stable micro/nanoscale surface roughness and superhydrophobic
functionality will be maintained over repeated use
and washing. However, nanoparticles have high van
der Waals forces with high specific surface area,
making it difficult to be uniformly dispersed in
solvents because of aggregation. Therefore, to make
the uniform deposits of nanoparticles and enhance the
adhesion on a fabric surface, surface modification of
nanoparticles as a pre-treatment is essential. In
addition, there is a possibility that nanoparticles that
dropp out of the fiber can pass through skin cell
membranes, casting growing concerns in academic
circles on biological effects. In 2013, a Safety Data
Sheet (SDS) preparation for manufactured
nanomaterials, ISO/TR 13329, was enacted related to
the hazardous influence of nano substances. This
shows that there is a need for prolonged research on
the effects of nanoparticles on the environment and
human body. The method of etching the fiber surface
instead of adding particles on the fiber surface to
form micro/nano-scale surface roughness can be
regarded as a more environmentally-responsible
process free from controversies over the hazards
resulting from dropped out nanoparticles. However,
in order to form nano-pillar type surface structures
with large aspect ratios, vacuum plasma processing is
found to be more effective, becoming a costly
process for large-scale manufacturing. Follow-up
research on process conditions that allow mass
production would be required.
Lowering fiber surface free energy is a simple and
effective method for coating compounds with low
surface tension. For methods that apply processing
agents on textiles, there is dip-coating that coats
processing agents on the entire fabric, spin/spray
coating that sprays only on the surface, and knife
coating and foam coating. Such coating methods can
adjust thickness of a coating layer formed on the
textile surface relatively easily with the advantage
that it can be mass produced without being limited by
the type of textile or coating substance. However,
after coating, it can affect the physical/chemical
properties of the textile, possibly creating a negative
influence on clothing comfort. Coating agents can
block the pores by forming an impermeable layer
resulting in lower air permeability, vapor
transmission, and moisture absorption of textiles.
This would prevent sweat from being transmitted to
the outside of clothes raising the humidity within the
clothes to give an unpleasant feeling to the body. Also,
when it is cold, vapors can condense inside.
Meanwhile, wet-processes, such as a dipping method
are being used for a wide array of purposes for the
fiber and textile industries, where the coating
material is fixed through dipping, drying, and heattreating and the remaining process residues are
removed. For the wet process, resource usage of
water and electricity are high, and the need for
development of and conversion to environmentally
responsible processing methods has been rising. Dryprocesses that transform fiber surfaces to low surface
free energy include plasma or laser process
techniques where a thin film in several nanometers
coats the fabric by vaporizing or ionizing compounds
that physically or chemically bond with the fiber
surface. This process does not block pores or make
the other face hydrophobic unlike dipping or spray
coating. This is advantageous in maintaining the
intrinsic properties of textiles. Processes of such
methods have little effect on the intrinsic
physical/chemical properties of textiles, and can have
little impact on comfort properties of clothes. There
is still room for research to achieve economic
development by optimizing process parameters in
engineered superhydrophobic textiles. Also, more
study is needed to learn about the functional
sustainability over repeated use, abrasion, and
washings.
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
Superhydrophobic textile research until now focused
on fabrication methods for superhydrophobic
functionality, but there was not enough review on the
practicality of processing methods for the final use
and commercialization of textiles. In future studies,
efforts to select developed technologies appropriate
to final use are needed.
EVALUATION OF SUPERHYDROPHOBIC
TEXTILES
The evaluation of superhydrophobic textiles are
summarized
in
Table
II.
Evaluation
of
superhydrophobicity is made up mainly of WCA,
CAH, SA, and SHA, and there are differences in the
measurement methodology and resulting values
(droplet size, dropping distance, the number of
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Plasma Treatment of
Thermo active
Membrane Textiles for
Superhydrophobicity
experiment repetitions, etc.). Evaluations on the
wearing comfort that considers the application in
clothing materials and the functional durability have
only been conducted in a few studies.
TABLE II. Evaluation item analysis of superhydrophobic textile
research.
Title
Microwave plasma
induced grafting of oleic
acid on cotton fabric
surfaces
Preparation and
characterizations of
PTFE gradient
nanostructure on silk
fabric
Superhydrophobic
behavior of plasma
modified electrospun
cellulose nanofibercoated microfibers
Superamphiphilic Janus
Fabric
Journal
Evaluation
Applied
Surface
Science /2012
World
Scientific
/ 2007
/
Langmuir
2012
/
WCA
WCA
porosity&pore size
distribution
Silicone nanofilaments
and their application as
superhydrophobic
coating
Advanced
Materials
/ 2006
water shedding
angle (SHA)
Tensile strength
Color difference
A simple, one-step
approach to durable and
robust superhydrophobic
textiles
Advanced
Functional
Materials/
2008
WCA,
Durability(textile
friction
analyzer[TFA])
Textile
Research
Journal / 2009
Durability
(laundering,
crocking tests)
Journal of
Materials
Chemistry /
2007
WCA,
water absorbability
Journal of
Materials
Chemistry /
2008
WCA,
Flammability
UV-blocking
property
CNT Wash fastness
Surface &
Coatings
Technology /
2011
WCA
Journal of
Applied
Polymer
Science /
2004
WCA,
surface energy,
drop penetration
time
oil repellency test
[AATCC 118]
Durable hydrophobic
textile fabric finishing
using silica nanoparticles
and mixed silanes
Artificial lotus leaf
structures from
assembling carbon
nanotubes and their
applications in
hydrophobic textiles
Functionalization of
cotton with carbon
nanotubes
Use of atmospheric
pressure plasma to confer
durable water repellent
functionality and
antimicrobial
functionality on
cotton/polyester blend
Modification of Low
Energy Polymer Surfaces
by Immobilization of
Fluorinated Carboxylates
with Zirconium-Based
Coupling Agents
Journal of Engineered Fibers and Fabrics
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WCA
Water repellency
[AATCC spray test
22-2005],
WCA,
Air permeability[IS
11056-2006],
water vapor
transmission[ASTM
-E 96(2005)],
WCA,
wet-out
time[AATCC]
water vapour
permeability
tensile
strength[HKS-5]
Atmospheric pressure
plasma polymerization
of HMDSO for
imparting water
repellency CTTN
fabric
Textile
Research
Journal / 2011
Improvement of
hydrophobic properties
of silk and cotton by
hexafluoropropene
plasma treatment
Applied
Surface
Science /
2007
Fabrication of a
superhydrophobic ZnO
nanorod array film on
cotton fabrics via a wet
chemical route and
hydrophobic
modification
Applied
Surface
Science /
2008
WCA
Superhydrophobic cotton
fabrics prepared by solgel coating of TiO2 and
surface hydrophobization
Science of
Technology
and Advanced
Material/
2008
WCA,
UV-Shielding
properties
Thin Solid
Films / 2009
WCA,
thermo gravimetric
analysis
Royal Society
of Chemistry
/ 2013
Water shedding
angle(SHA),
Abstraction test
laundering test,
oil/water separation
Applied
Surface
Science /
2010
WCA CA hysteresis,
washing durability
WCA
WCA,
CA hysteresis
Cellulose
2012
Materials
Science /
2012
Superhydrophobic
surfaces on cotton
textiles by complex
coating of silica
nanoparticles and
hydrophobization
Mimic nature, beyond
nature: facile synthesis
of durable
superhydrophobic
textiles using
organosilanes
Superhydrophobic cotton
fabric fabricated by
electrostatic assembly of
silica nanoparticles and
its remarkable buoyancy
WCA, which is one of the most representative
evaluation methods for measuring hydrophobicity
[29], is a simple measurement technique, but has
limitations in that there can be experimental errors
due to the effects of gravity caused by the size of the
liquid and irregular baseline of the textile surface.
When the measured lighting, contrast, lens focus, and
contact base-line of water and surface were changed
in the studies of Zimmermann et al., [51], WCA of
the same surface was shown to vary by more than 10°.
Furthermore, the instantaneous energy produced
when a water drop contacts a textile surfaces depends
on the load amount and load height, and affects
WCA; a smaller drop tends to generate higher
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WCA. However, there are as yet no testing
specifications on WCA measurements that can
minimize such testing discrepancies. Also, in the case
of superhydrophobic surfaces with high WCA values,
it is difficult to discriminate the level of
hydrophobicity. Error can also occur on the angle for
slanting the plate for CAH, SA, and SHA, and it is
difficult to not only obtain clear images for the rolloff moment, but also to accurately set the base-line
due to the surface features unique to fabrics. As a
method to more easily measure CAH, captive drop
methods are used where automated equipment is
needed to adjust the fluctuation of the water with
high-resolution camera settings that can film over 20
frames per second. For consistent measurement,
concrete evaluation standards that define appropriate
load height, load amount, and measurement processes
for evaluating the wetting characteristics and the
level of hydrophobicity of textiles are needed.
the quantity of water or falling energy. However, in
order for the developed superhydrophobic textiles to
have applications for clothing materials recognized, it
is necessary to examine water-repellency in real life.
Standard evaluation methods are often used to
determine the level of water-repellency; such
standards are the spray test (AATCC22-2005 Water
Repellency: Spray Test, ISO4920, KS K 0590), rain
test (AATCC35-2006 water resistance: rain test) and
drop penetration test (AATCC42-2007 water
resistance: impact penetration test) [90]. As
superhydrophobic textiles are a relatively new
pioneered research sector, there are limitations to
determining the characteristics of superhydrophobicity, and further study is needed on developing
measurement methods for superhydrophobic
functionality, self-cleaning performance, and oil
repellency performance for textile materials.
NEW
RESEARCH
FIELD
FOR
SUPERHYDROPHOBIC TEXTILE RESEARCH
Recent studies on superhydrophobic textiles are
making multi-faceted evaluations considering use as
clothing materials focusing on the aforementioned
limitations and problems, and there are attempts
being
made
to
develop
multi-functional
superhydrophobic textiles that go beyond just
configuring superhydrophobicity.
In order to resolve such issues, the shedding angle
(SHA) measurement method was drawn up as a more
convenient measurement to differentiate the level of
hydrophobicity for superhydrophobic surfaces. This
measures the 2 cm-rolling angle of water drops when
12.5㎕ of water is dropped at 1 cm on a specimen
(Figure 14). SHA was used in many
superhydrophobic fabric studies as an efficient
evaluation method for superhydrophobic textiles [89].
FIGURE 15. (a) Measurement errors that can occur when
measuring WCA [89]. (b) Shedding angle (SHA) measurement
method [89].
WCA and CAH measurement is an evaluation
method focusing on superhydrophobicity of surfaces
while excluding the effects of external factors such as
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
13
There are studies that have examined the effects of
superhydrophobic processing methods on the comfort
properties required for clothing textiles such as air
permeability, vapor transmission, and moisture
absorption. When water repellent agents were foamcoated on one face of a cotton fabric [91], the treated
fabric maintained softness and sweat absorption
property at adequate levels, which are advantages for
hydrophilic cotton fabrics. The resulting fabric
exhibited asymmetric wettability with one surface
being superhydrophobic and the other side being
hydrophilic. Compared to the non-treated fabric in
vapor transmission, the fabric that received double
side water-repellent treatment had 87% of the water
vapor transmission rate of the untreated fabric, while
fabrics that received a one-sided water-repellent
treatment showed a 94-99% water vapor transmission
rate compared to the untreated sample. When the
superhydrophobic side came into contact with the
ambient environment, it showed a 94% water vapor
transmission rate compared to non-treated fabrics,
and when facing the water, it showed a 99% water
vapor transmission rate. This was thought to be due
to the difference of hydrophilic/hydrophobic layers
affecting the transmission rate and amount of vapor.
In other words, when vapors transmit into the
hydrophilic layer, the vapor moves from the
http://www.jeffjournal.org
hydrophilic layer to the hydrophobic layer to be
pushed outside, and this behavior is opposite to the
regular movement tendencies of water and moisture.
Meanwhile, when vapors permeate into the
hydrophobic layer first, there is little absorption
occurring and vapor passes through the hydrophilic
layer and is absorbed in the upper hydrophilic layer.
When this hydrophilic layer comes into contact with
outside air, the moisture is easily evaporated. This
study also confirmed laundry durability and validated
the effectiveness of the single-sided foam coating
method through multi-faceted evaluation for
development of superhydrophobic textiles that
displayed asymmetrical wettability [91]. A plasma
treatment method was also evaluated for maintaining
comfort properties for air, vapor, and moisture,
configuring superhydrophobicity without changing
the original characteristics of the fabric too much [55,
64, 74].
superhydrophobic processing. Thus, there are
limitations in terms of functions, processing, and
economic aspects as clothing materials for use in
actual
life.
Furthermore,
superhydrophobic
evaluation methods do not consider the unique
characteristics of textiles and are conducted focusing
on WCA measurements. Therefore, it is necessary for
future studies to deal with the effectiveness of
superhydrophobic processing methods that can
satisfy not only the basic functional performance, but
also the comfort properties such as moisture
management, vapor transmission and air permeability,
bio-toxicity, safety, and functional durability over
repeated use and wash for use as clothing materials.
Furthermore, it is necessary to develop an evaluation
method that enables the differentiation of the level of
superhydrophobicity other than WCA, studying the
effect of liquid drop size and dropping height.
Development of evaluation methods for the selfcleaning effects of superhydrophobic fabrics would
also be another area of study, considering the
properties of contaminants.
Despite several studies that evaluated such comfort
properties, there are not enough studies for the
influence of superhydrophobic treatment on moisture
and heat transfer mechanisms. In addition,
configuration of multi-functional textile materials is
being made by adding other functions to
superhydrophobicity in textiles. Examples include
use of silver with antimicrobial effects [92, 93] or
graphene with electric conductivity and applying it
on fabrics in a nanoparticle form to configure fabrics
with not only superhydrophobicity, but also other
functionalities including antimicrobial [92, 93],
electrical conductivity [93], or UV protection [92].
CONCLUSION
Studies on superhydrophobic textiles experienced
rapid growth in a short period of time due to high
industrial
and
academic
value.
Also,
superhydrophobic textiles made with some
commercialized technologies are being sold in the
market. However, in the course of applying the
development and evaluations of related studies
focusing on superhydrophobic surface development,
there are not enough discussions on problems that
limit the use of superhydrophobic clothing materials
such as bio-suitability, clothing comfort, and
functional durability. In particular, basic safety
verification on nano-materials used for the
introduction of water-repellant processing materials
and surface roughening have not yet been made.
Therefore, sufficient verification on the use of
clothing materials as processing materials must be
made. In addition, there are problems that basic
performance for clothing such as durability of
functions and convenience of management has
reduced quality compared to demands after
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
There are efforts being made in various sectors for
sustainable development amidst the recent dangers of
environmental destruction. Superhydrophobic textiles
are thought to contribute to sustainable textile
development by reducing the use of water and energy,
and by possibly extending use life resulting from
extended functional durability with a reduced number
of washings. Therefore, positive ripple effects on
the environment and society can be expected when
superhydrophobic textiles are commercialized.
Accordingly, if the limitations are overcome for
commercialization, multi-functional superhydrophobic textiles may be able to further create
sustainable economic value.
ACKNOWLEDGEMENT
This research was supported by the National
Research Foundation of Korea (NRF) Grant funded
by the Korean Government (2011-0014765) and
Korea Textile Trade Association.
REFERENCE
[1] Barthlott, W. and Neinhuis, C.; Purity of the
sacred lotus, or escape from contamination in
biological surfaces; Planta 1997, 202,1.
[2] Lee, H. and Owens, J., Superhydrophobic
Superoleophobic Woven Fabrics, 2011.
[3] Ma, M. and Hill, R. M.; Superhydrophobic
surfaces; Current Opinion in Colloid &
Interface Science 2006, 11,193.
14
http://www.jeffjournal.org
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
Zhang, X., Shi, F., Niu, J., et al.;
Superhydrophobic surfaces: from structural
control to functional application; J. Mater.
Chem. 2008, 18,621.
Yong, J., Yang, Q., Chen, F., et al.; Bioinspired
superhydrophobic surfaces with directional
Adhesion; RSC Adv. 2014, 4,8138.
Tuteja, A., Choi, W., Mabry, J. M., et al.;
Robust omniphobic surfaces; Proc. Natl.
Acad. Sci. U. S. A. 2008, 105,18200.
Liu, K., Tian, Y., and Jiang, L.; Bio-inspired
superoleophobic and smart materials: design,
fabrication, and application; Progress in
Materials Science 2013, 58,503.
Nishimoto, S. and Bhushan, B.; Bioinspired
self-cleaning
surfaces
with
superhydrophobicity, superoleophobicity, and
superhydrophilicity; RSC Adv. 2013, 3,671.
Young, T.; An essay on the cohesion of fluids;
Philosophical Transactions of the Royal
Society of London 1805, 65.
Zisman, W. A.; Influence of constitution on
adhesion;
Industrial
&
Engineering
Chemistry 1963, 55,18.
Wenzel, R. N.; Resistance of solid surfaces to
wetting by water; Industrial and Engineering
Chemistry 1936, 28,988.
Cassie, A. and Baxter, S.; Wettability of porous
surfaces; Transactions of the Faraday Society
1944, 40,546.
Lafuma, A. and Quéré, D.; Superhydrophobic
states; Nat. Mater. 2003, 2,457.
Autumn, K., Liang, Y. A., Hsieh, S. T., et al.;
Adhesive force of a single gecko foot-hair;
Nature 2000, 405,681.
Hancock, M. J., Sekeroglu, K., and Demirel, M.
C.; Bioinspired Directional Surfaces for
Adhesion, Wetting, and Transport; Adv. Funct.
Mater. 2012, 22,2223.
Sethi, S., Ge, L., Ci, L., et al.; Gecko-Inspired
Carbon
Nanotube-Based
Self-Cleaning
Adhesives; Nano Letters 2008, 8,822.
[17] Aksak, B., Murphy, M. P., and Sitti, M.
Robotics and Automation, 2008. ICRA 2008.
IEEE International Conference on, p. 30583063.
Patankar, N. A.; Mimicking the lotus effect:
Influence of double roughness structures and
slender pillars; Langmuir 2004, 20,8209.
Patankar, N. A.; On the modeling of
hydrophobic contact angles on rough
surfaces; Langmuir 2003, 19,1249.
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
15
[20] Cheng, Y. T., Rodak, D. E., Wong, C. A., et al.;
Effects of micro- and nano-structures on the
self-cleaning behaviour of lotus leaves;
Nanotechnology 2006, 17,1359.
[21] Bhushan, B. and Jung, Y. C.; Wetting study of
patterned surfaces for superhydrophobicity;
Ultramicroscopy 2007, 107,1033.
[22] Lee, Y. W., Park, S. H., Kim, K. B., et al.;
Fabrication of hierarchical structures on a
polymer
surface
to
mimic
natural
superhydrophobic surfaces; Adv. Mater. 2007,
19,2330.
[23] Koch, K., Bhushan, B., Jung, Y. C., et al.;
Fabrication of artificial Lotus leaves and
significance of hierarchical structure for
superhydrophobicity and low adhesion; Soft
Matter 2009, 5,1386.
[24] Tuteja, A., Choi, W. J., McKinley, G. H., et al.;
Design parameters for superhydrophobicity
and superoleophobicity; MRS Bull. 2008,
33,752.
[25] Tuteja, A., Choi, W., Ma, M., et al.; Designing
superoleophobic surfaces; Science 2007,
318,1618.
[26] Yang, J., Zhang, Z., Xu, X., et al.;
Superoleophobic textured aluminum surfaces;
New Journal of Chemistry 2011, 35,2422.
[27] Chhatre, S. S., Choi, W., Tuteja, A., et al.; Scale
dependence of omniphobic mesh surfaces;
Langmuir 2009, 26,4027.
[28] Saraf, R., Lee, H. J., Michielsen, S., et al.;
Comparison of three methods for generating
superhydrophobic, superoleophobic nylon
nonwoven surfaces; J. Mater. Sci. 2011,
46,5751.
[29] Degennes, P. G.; WETTING - STATICS AND
DYNAMICS; Rev. Mod. Phys. 1985, 57,827.
[30] Li, J., Zhang, Z., Xu, J., et al. in Kirk-Othmer
Encyclopedia of Chemical Technology, John
Wiley & Sons, Inc., 2000.
[31] Gao, L. C. and McCarthy, T. J.; Teflon is
hydrophilic. Comments on definitions of
hydrophobic,
shear
versus
tensile
hydrophobicity,
and
wettability
characterization; Langmuir 2008, 24,9183.
[32] Petrie, E. M.; Handbook of adhesives and
sealants; 2000.
[33] Patrick, R., Treatise on adhesion and adhesives,
CRC Press, 1981.
[34] Armitage, J. M., MacLeod, M., and Cousins, I.
T.; Comparative Assessment of the Global
Fate and Transport Pathways of Long-Chain
Perfluorocarboxylic Acids (PFCAs) and
Perfluorocarboxylates (PFCs) Emitted from
Direct Sources; Environmental Science &
Technology 2009, 43,5830.
http://www.jeffjournal.org
[35] Zhu, Q., Gao, Q. W., Guo, Y. L., et al.;
Modified Silica Sol Coatings for Highly
Hydrophobic Cotton and Polyester Fabrics
Using a One-Step Procedure; Ind. Eng. Chem.
Res. 2011, 50,5881.
[36] Bae, G. Y., Min, B. G., Jeong, Y. G., et al.;
Superhydrophobicity of cotton fabrics treated
with silica nanoparticles and water-repellent
agent; J. Colloid Interface Sci. 2009, 337,170.
[37] Roe, B. and Zhang, X.; Durable hydrophobic
textile fabric finishing using silica
nanoparticles and mixed silanes; Text. Res. J.
2009, 79,1115.
[38] Zhao, Y., Tang, Y., Wang, X., et al.;
Superhydrophobic cotton fabric fabricated by
electrostatic assembly of silica nanoparticles
and its remarkable buoyancy; Appl. Surf. Sci.
2010.
[39] Wu, L., Zhang, J., Lia, B., et al.; Mimic nature,
beyond nature: facile synthesis of durable
superhydrophobic
textiles
using
organosilanes;
Journal
of
Materials
Chemistry B 2013.
[40] Ramaratnam, K., Iyer, S. K., Kinnan, M. K., et
al.;
Ultrahydrophobic
Textiles
Using
Nanoparticles: Lotus Approach; J. Eng. Fiber
Fabr. 2008, 3,1.
[41] [41] Xue, C.-H., Jia, S.-T., Zhang, J., et al.;
Superhydrophobic surfaces on cotton textiles
by complex coating of silica nanoparticles
and hydrophobization; Elsevier 2009.
[42] Athauda, T. J. and Ozer, R. R.; Investigation of
the effect of dual-size coatings on the
hydrophobicity of cotton surface; Cellulose
2012, 19,1031.
[43] Xue, C.-H., Jia, S.-T., Chen, H.-Z., et al.;
Superhydrophobic cotton fabrics prepared by
sol–gel coating of TiO2 and surface
hydrophobization; Science and Technology of
Advanced Materials 2008, 9,035001.
[44] Xue, C.-H., WeiYin, Jia, S.-T., et al.; UVdurable superhydrophobic textiles with UVshielding properties by coating fibers with
ZnO/SiO2
core/shell
particles;
NANOTECHNOLOGY 2011.
[45] Liu, Y. Y., Wang, R. H., Lu, H. F., et al.;
Artificial lotus leaf structures from
assembling carbon nanotubes and their
applications in hydrophobic textiles; J. Mater.
Chem. 2007, 17,1071.
[46] Li, G. A., Wang, H., Zheng, W. T., et al.; A
Facile Approach for the Fabrication of Highly
Stable Superhydrophobic Cotton Fabric with
Multi-Walled
Carbon
Nanotubes-Azide
Polymer Composites; Langmuir 2010,
26,7529.
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
[47] Shim, M. H., Kim, J., and Park, C. H.; The
effects of surface energy and roughness on
the hydrophobicity of woven fabrics; Text.
Res. J. 2014, 0040517513495945.
[48] Goncalves, A. G., Jarrais, B., Pereira, C., et al.;
Functionalization of textiles with multiwalled carbon nanotubes by a novel dyeinglike process; J. Mater. Sci. 2012, 47,5263.
[49] Gonçalves, A., Jarrais, B., Pereira, C., et al.;
Functionalization of textiles with multiwalled carbon nanotubes by a novel dyeinglike process; J. Mater. Sci. 2012, 47,5263.
[50] Shateri-Khalilabad, M. and Yazdanshenas, M.
E.;
Preparation
of
superhydrophobic
electroconductive graphene-coated cotton
cellulose; Cellulose 2013, 1.
[51] Zimmermann, J., Reifler, F. A., Fortunato, G., et
al.; A Simple, One-Step Approach to Durable
and Robust Superhydrophobic Textiles; Adv.
Funct. Mater. 2008, 18,3662.
[52] Xu, B. and Cai, Z.; Fabrication of a
superhydrophobic ZnO nanorod array film on
cotton fabrics via a wet chemical route and
hydrophobic modification; Appl. Surf. Sci.
2008, 254,5899.
[53] Xu, B., Cai, Z. S., Wang, W. M., et al.;
Preparation of superhydrophobic cotton
fabrics based on SiO2 nanoparticles and ZnO
nanorod arrays with subsequent hydrophobic
modification; Surf. Coat. Technol. 2010,
204,1556.
[54] Lei, J. X., Shi, M. W., and Zhang, J. C.; Surface
graft copolymerization of hydrogen silicone
fluid onto fabric through corona discharge
and water repellency of grafted fabric; Eur.
Polym. J. 2000, 36,1277.
[55] Pane, S., Tedesco, R., and Greger, R.; Acrylic
fabrics treated with plasma for outdoor
applications; J. Ind. Text. 2001, 31,135.
[56] Riccardi, C., Barni, R., Fontanesi, M., et al.; A
SF6 RF plasma reactor for research on textile
treatment; Plasma Sources Sci. Technol. 2001,
10,92.
[57] Hochart, F., De Jaeger, R., and LevaloisGrutzmacher, J.; Graft-polymerization of a
hydrophobic monomer onto PAN textile by
low-pressure plasma treatments; Surf. Coat.
Technol. 2003, 165,201.
[58] Zhang, J., France, P., Radomyselskiy, A., et al.;
Hydrophobic cotton fabric coated by a thin
nanoparticulate plasma film; J. Appl. Polym.
Sci. 2003, 88,1473.
16
http://www.jeffjournal.org
[59] Tsafack, M. J., Hochart, F., and LevaloisGrutzmacher, J.; Polymerization and surface
modification by low pressure plasma
technique; Eur. Phys. J.-Appl. Phys 2004,
26,215.
[60] Hegemann, D.; Stain repellent finishing on
fabrics; Adv. Eng. Mater. 2005, 7,401.
[61] Chaivan, P., Pasaja, N., Boonyawan, D., et al.;
Low-temperature plasma treatment for
hydrophobicity improvement of silk; Surf.
Coat. Technol. 2005, 193,356.
[62] Vaswani, S., Koskinen, J., and Hess, D. W.;
Surface modification of paper and cellulose
by plasma-assisted deposition of fluorocarbon
films; Surface and Coatings Technology 2005,
195,121.
[63] Kim, S. H., Kim, J. H., Kang, B. K., et al.;
Superhydrophobic CFx coating via in-line
atmospheric RF plasma of He-CF4-H-2;
Langmuir 2005, 21,12213.
[64] Li, S. and Jinjin, D.; Improvement of
hydrophobic properties of silk and cotton by
hexafluoropropene plasma treatment; Appl.
Surf. Sci. 2007, 253,5051.
[65] Hodak, S. K., Supasai, T., Paosawatyanyong, B.,
et al.; Enhancement of the hydrophobicity of
silk fabrics by SF6 plasma; Appl. Surf. Sci.
2008, 254,4744.
[66] Morent, R., De Geyter, N., Verschuren, J., et al.;
Non-thermal plasma treatment of textiles;
Surface and Coatings Technology 2008,
202,3427.
[67] Cho, S. C., Hong, Y. C., Cho, S. G., et al.;
Surface modification of polyimide films,
filter papers, and cotton clothes by
HMDSO/toluene plasma at low pressure and
its wettability; Current Applied Physics 2009,
9,1223.
[68] Kale, K. H. and Palaskar, S.; Atmospheric
pressure
plasma
polymerization
of
hexamethyldisiloxane for imparting water
repellency to cotton fabric; Text. Res. J. 2011,
81,608.
[69] Davis, R., El-Shafei, A., and Hauser, P.; Use of
atmospheric pressure plasma to confer
durable water repellent functionality and
antimicrobial
functionality
on
cotton/polyester blend; Surface and Coatings
Technology 2011, 205,4791.
[70] Boguslavsky, Y., Fadida, T., Talyosef, Y., et al.;
Controlling the wettability properties of
polyester fibers using grafted functional
nanomaterials; J. Mater. Chem. 2011,
21,10304.
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
[71] Cabrales, L. and Abidi, N.; Microwave plasma
induced grafting of oleic acid on cotton fabric
surfaces; Appl. Surf. Sci. 2012, 258,4636.
[72] Joneydi, S., Khoddami, A., and Zadhoush, A.;
Novel superhydrophobic top coating on
surface modified PVC-coated fabric; Prog.
Org. Coat. 2013, 76,821.
[73] Huang, F. L., Wei, Q. F., Liu, Y., et al.; Surface
functionalization of silk fabric by PTFE
sputter coating; J. Mater. Sci. 2007, 42,8025.
[74] Shin, B., Lee, K.-R., Moon, M.-W., et al.;
Extreme water repellency of nanostructured
low-surface-energy non-woven fabrics; Soft
Matter 2012, 8,1817.
[75] Wei, Q. F., Liu, Y., Hou, D. Y., et al.; Dynamic
wetting behavior of plasma treated PET
fibers; J. Mater. Process. Technol. 2007,
194,89.
[76] Riccardi, C., Barni, R., Selli, E., et al.; Surface
modification of poly(ethylene terephthalate)
fibers induced by radio frequency air plasma
treatment; Appl. Surf. Sci. 2003, 211,386.
[77] Poletti, G., Orsini, E., Raffaele-Addamo, A., et
al.; Cold plasma treatment of PET fabrics:
AFM surface morphology characterisation;
Appl. Surf. Sci. 2003, 219,311.
[78] Bahners, T., Prager, L., Pender, A., et al.; Superwetting surfaces by plasma- and UV-based
grafting of micro-rough acrylate coatings;
Prog. Org. Coat. 2013, 76,1356.
[79] Twardowski, A., Makowski, P., Malachowski,
A., et al.; Plasma Treatment of Thermoactive
Membrane Textiles for Superhydrophobicity;
Mater. Sci.-Medzg. 2012, 18,163.
[80] Ko, T. J., Her, E. K., Shin, B., et al.; Water
condensation behavior on the surface of a
network of superhydrophobic carbon fibers
with
high-aspect-ratio
nanostructures;
Carbon 2012, 50,5085.
[81] Mazrouei-Sebdani, Z. and Khoddami, A.;
Alkaline hydrolysis: A facile method to
manufacture superhydrophobic polyester
fabric by fluorocarbon coating; Prog. Org.
Coat. 2011, 72,638.
[82] Kang, Y. K., Park, C. H., Kim, J., et al.;
Application of electrospun polyurethane web
to breathable water-proof fabrics; Fibers and
Polymers 2007, 8,564.
[83] Lim, H. S., Park, S. H., Koo, S. H., et al.;
Superamphiphilic Janus Fabric; Langmuir
2010, 26,19159.
[84] Thorvaldsson, A., Edvinsson, P., Glantz, A., et
al.; Superhydrophobic behaviour of plasma
modified electrospun cellulose nanofibercoated microfibers; Cellulose 2012, 19,1743.
17
http://www.jeffjournal.org
[85] Il Yoon, Y., Moon, H. S., Lyoo, W. S., et al.;
Superhydrophobicity of cellulose triacetate
fibrous mats produced by electrospinning and
plasma treatment; Carbohydr. Polym. 2009,
75,246.
[86] Wang, J., Raza, A., Si, Y., et al.; Synthesis of
superamphiphobic breathable membranes
utilizing SiO2 nanoparticles decorated
fluorinated
polyurethane
nanofibers;
Nanoscale 2012, 4,7549.
[87] Choi, G. R., Park, J., Ha, J. W., et al.;
Superamphiphobic Web of PTFEMA Fibers
via
Simple
Electrospinning
Without
Functionalization; Macromol. Mater. Eng.
2010, 295,995.
[88] Miyauchi, Y., Ding, B., and Shiratori, S.;
Fabrication of a silver-ragwort-leaf-like
super-hydrophobic micro/nanoporous fibrous
mat
surface
by
electrospinning;
Nanotechnology 2006, 17,5151.
[89] Zimmermann, J., Seeger, S., and Reifler, F. A.;
Water Shedding Angle: A New Technique to
Evaluate the Water-Repellent Properties of
Superhydrophobic Surfaces; Text. Res. J.
2009, 79,1565.
[90] Bahners, T.; The Do's and Don'ts of Wettability
Characterization in Textiles; J. Adhes. Sci.
Technol. 2011, 25,2005.
[91] Liu, Y. Y., Xin, J. H., and Choi, C. H.; Cotton
Fabrics
with
Single-Faced
Superhydrophobicity;
Langmuir
2012,
28,17426.
[92] Khalil-Abad, M. S. and Yazdanshenas, M. E.;
Superhydrophobic
antibacterial
cotton
textiles; J. Colloid Interface Sci. 2010.
[93] Xue, C.-H., Chen, J., Yin, W., et al.;
Superhydrophobic conductive textiles with
antibacterial property by coating fibers with
silver nanoparticles; Appl. Surf. Sci. 2012,
258, 2468.
AUTHORS’ ADDRESSES
Sohyun Park
Jooyoun Kim, PhD
Chung Hee Park, PhD
Seoul National University
222 Dong, 323 Ho
Seoul 151-742
KOREA
Journal of Engineered Fibers and Fabrics
Volume 10, Issue 4 – 2015
18
http://www.jeffjournal.org