Soft condensed matter
Materials which are easily deformable by external stresses,
electric or magnetic fields, or even by thermal fluctuations;
typically possess structures which are much larger than
atomic or molecular scales; the structure and dynamics at the
mesoscopic scales determine macroscopic physical
properties. http://www.seas.harvard.edu/weitzlab/
Soft condensed matter
(Soft amtter)
Polymers
Colloids
Amphiphiles (surfactants, lipid)
Liquid crystals
Molecular crystals
Biological matter
Monday 27/10
8:00-10:00
P18
Terminology and statistics
FZ
Tuesday 28/10
10:00-12:00
P30
Chain conformation
FZ
Thursday 30/10
13:00-15:00
P26
The rubber elastic state
FZ
Monday 3/11
08:00-10:00
P26
Polymer solution
FZ
Tuesday 4/11
10:00-12:00
P30
Glassy amorphous state
FZ
Thursday 6/11
13:00-15:00
P30
molten state
FZ
Monday 10/11
08:00-10:00
P18
Problem class
VA
Tuesday 11/11
10:00-12:00
P30
Crystalline polymers
FZ
Thursday 13/11
13:00-15:00
P30
Soft Matter
NS
Monday 17/11
08:00-10:00
P26
Soft Matter
NS
Tuesday 18/11
10:00-12:00
P30
Biopolymers
NS
Thursday 20/11
13:00-15:00
IFM
Lab1
VA and FZ
Monday 24/11
08:00-10:00
P22
Electronic polymers
OI
Tuesday 25/11
10:00-12:00
P34
Electronic polymers
OI
Thursday 27/11
13:00-15:00
IFM
Lab2
VA and FZ
Monday 1/12
08:00-10:00
P26
Application of electronic polymers
FZ
Tuesday 2/12
10:00-12:00
P30
Summary
FZ
Thursday 4/12
13:00-15:00
P26
Problem class
VA
Friday 12/12
08:00-12:00
Examination
1
2
Chapter 1 Introduction to polymer physics
Insulating polymers
Biopolymers (natural polymers)
Polymers
Synthetic polymers
Biopolymers are produced by living system, for instance, silk, wool, more?
produced by the chemical industry, plastics,
rubbers, fibers (big scale, 106 ton/year)
Synthetic polymers
Bokakademin in Kårallen, Campus Valla.
synthesized by researchers in labs (small scale, mg)
Conductive polymers and others mostly base on
research articles.
3
Why polymers are so useful?
Polymer semiconductors
• The properties of polymers are very diverse and can be
modified to meet the special requirements of applications
Some conjugated (semi-conducting) polymers
S
n
n
Polythiophene
Polyacetylene
4
Characterized by
typical
-electrical
-optical properties
n
n
Poly (para-phenylene-vinylene)
http://www.planete-energies.com/content/features/plastics/applications.html
http://www.thinfilm.se/index.php?option=com_content&task=blogcategory&id=0&Itemid=59
They are versatile.
Polyfluorene
5
6
http://www.polymervision.com/
http://www.konarka.com/
1
Electrical property
Anisotropic mechanical property (Young’s
modulus)
O
O
O
S
+
S
O
O
O
O
O
+
S
S
S
O
O
S
O
O
_
_
O
O
OH
O S OO S OO S O
PEDOT-PSS
poly(3,4-ethylenedioxythiophene) and
poly(styrene sulfonate) (Baytron PH500)
8
7
An introduction to polymer physics, David I Bower
Optical properties and structures of polymers
Y-H. Zhou, F. Zhang, et al., App. Phys. Lett., 92, 233308 (2008).
The variety of polymer materials
Physical state:
S
N
N
S
S
δ+
S
N
S
δ-
N
O
S
S
N
S
S
n
N
N
n
O
N
n
O
δ+
APFO3 (Alternating polyfluorenes)
O
O
O
APFO-Green5
LBPP1(Low bandgap
polyphenylene)
crystallisation is not complete, semi-crystalline.
• Liquid crystalline: Some polymers can line up to
1 .6
-2 -1
AM1.5 (Global tilt, wm nm )
• Liquid: polymer melts and solutions (very viscous)
• Crystalline: polymer can crystallize, but usually
1 .4
form liquid crystalline materials.
1 .2
1 .0
• Glasses: amorphous solid.polymer glasses are very
0 .8
common, polystyrene, poly(methyl methacrylate)
0 .6
0 .4
F. Zhang, et al, APL 84(19), (2004), 3906.
F. Zhang, et al, Adv. Mater. 18, 2169 (2006).
0 .2
0 .0
400
600
800
1000
1200
1400
E. Perzon, et al, Adv. Mater. 19, 3308(2007).
9
W a v e le n g th (n m )
10
1.1 Fundamental definition
• Physics:
Polymer (Macromolecule):
Explain phenomenon, behavior and find correlation
among variables and rules.
A substance composed of molecules by the multiple repetition of one or more
species of atoms or group of atoms (constitutional repeating units) linked each
other in amounts sufficient to provide a set of properties that do not vary
markedly with the addition of one or a few of the constitutional repeating unts.
(Swedish chemist Jöns Jacob Berzelius invented in 1832)
• Polymer physics:
Describe the properties of polymers and explain the
correlation between microstructure and macro
properties.
Polyethylene
polypropylene
determine
microstructure
macro properties
How?
n=103~106
To modify property
Poly (para-phenylenevinylene)
Applications need special properties
Design molecular structures
11
12
n
2
Oligomer:
Monomer:
A molecule with only a few constitutinal repeating units.
is the substance that the polymer is made
from.
Monomer
2,2',5',2''-Terthiophene (3T)
Polymerization
Polymer
2,2',5',2'',5'',2'-Quaterthiophene (4T)
propylene
polypropylene
Polymerization
a-Sexithiophene (6T)
a,w-Dihexylsexithiophene (DH-6T)
http://www.sigmaaldrich.com/Area_of_Interest/Chemistry/Materials_Science/Energy_Source_Materials/Conducting_Polymers/Conductive
_Thiophene_Oligomers.html
Physical properties vary with n, mp (93-95°C, 211-214°C, 290°C, 280°C )
13
Repeating unit
14
Covalent bonds
Bonds in polymers
Bonds
σ and π bond
Link the atoms of the polymer
chains, which are very strong with
dissociation energy 300-500 kJ/mol
Primary bond (covalent bond)
Ethane (C2H6)
Secondary bond
Two elements share an electron pair, form bond
Bond energy
Bond stability
Ethylene (Ethene)(C2H4)
Physical properties
(Modulus)
RT ~2.5kJ/mol (300K), 4kJ/mol at 500K
Difference between σ and π bond ?
15
Secondary bonds
1.2 Configuration (”Permanent” stereostructure of a polymer )
The interaction between atoms of different molecules
(important for the properties of polymers)
Van der Waals bond
Dipole-dipole bond
Hydrogen bond
Polymerization method determines configuration
If a polymer has more than one type of chemical group attached to each
main chain carbon atom, then different arrangments of the groups in three
dimensions are possible.
~10kJ/mol
>10kJ/mol
10 ~50kJ/mol
C2H2XY
Dispersion forces (London forces)
Isotactic(similar side groups
appear on the same side of the
chain)
acts between all atoms and molecules
Dipole-dipole bond
u=ql
16
dipole moment
Syndiotactic(on alternate sides)
Induced dipole moment
Hydrogen bond
Atactic(random arrangement of
the groups).
17
18
3
Polymers with double bonds
determine
Double bond is rigid and allows no torsion, and the cis and trans
forms are not transferable into each other.
microstructure
macro properties
How?
1,4-polybutadiene
Atactic (irregular configuration)
Isotactic (regular configuration)
Amorphous
Crystalline
Totally depends on configuration (local geometry)
Stereoforms of 1,4-polybutadiene showing only the constitutional repeating
unit with the rigid central double bond
19
1.3 Homopolymer and copolymer
The entire structure of a polymer is generated during polymerization
20
1.4 Molecular Architecture (organize chains)
Homopolymer consists only one type of monomer (A):
A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-
Copolymer consists 2 or more monomers (A, B,…): (why do we need
copolymers? )
Block copolymer, Graft copolymer, Alternating copolymer, Random copolymer
21
Organize monomer
Structure
22
Crosslinked polymer
properties
lightly crosslinked polymers are reversibly
stretchable to high extensions (Rubber or
elastomers)
Linear polymer, atoms more or less arranged in a long chain
(backbond)(102-103), if small chain (few atoms) attached (pendant group)
A-A-A-A-A-A-A-A-A-A-A-A-A-A-A-AB
B
heavily crosslinked polymers are
normally rigid, can not melt on
heating and they decompose if T is
high enough (Thermosets).
B
Branched polymer if B getting longer, comparable to the length of the
backbone chain.
Sometimes there is no backbond at all. A
polymer is built in such a way that
branches keep growing out of branches
and more branches grow out of those
branches. (Dendrimers)
Star polymer
Profound effects on rheological
properties, chain mobility
linear or branced polymer soften or melt when heated, so that they can be
moulded and remoulded by heating (Thermoplastics).
23
Used as additives in motor oil
24
http://www.diva-portal.org/kth/theses/abstract.xsql?dbid=4808
4
1.5 Conformation:
A conformational state refers to the stereostructure of a
molecule defined by its sequence of bonds and torsion
angles.
Example of conformational states of C7H16. The right-hand form is generated
from the left-hand form by 120°torsion about the σ bond indicated by the arrow.
The polymer characteristics, such as microstructure,
architecture, degree of polymerization (n), chemical
composition of heteropolymer (copolymer) are all fixed
during polymerization and can not be changed without
breaking covalent bonds.
However, a single flexible macromolecule can adopt many
different conformations. Conformation is the spatial
structure of a polymer determined by the relative
locations of its monomers.
Conformation depends on
Flexibility of the chain
Interaction between monomers on the chain
Interaction with surroundings
T
Relative strength of
Attractive
Repulsive
25
26
How the interaction influence the conformation?
Consider a chain with n=1010 bonds, l ≈ 10-10m, contour length L=nl=1010×1010 ≈ 1m
Magnify all lengths by 108, that is l ≈ 1cm
1.
2.
3.
4.
strong attraction between monomers, the conformation of the polymer is a dense
object called collapsed globule, V ≈ nl3 ≈ 104m3, R=3√V≈20 m, a classroom
No interaction between monomers, Random walk, R ≈n1/2l ≈ 103 m, a campus
With excluded volume repulsions, R ≈ n3/5 l ≈10 km, a city
With long-range repulsions, R ≈ nl ≈ 105 km, the order of the distance to the
Moon.
•
•
•
•
Cofiguration? How to change
Conformation? How to change
Why flexibility increase with T
Why rubber rapid response to external
force
More on conformation in Next Chapter
The multitude of conformations available for polymers is very
important for their properties
27
28
1.5 Commen polymers
Properties: Flexible at low temperature, colorless, non-toxic transparent. High
density PE(HDPE) is hard, tough and resilient. Most of HDPE is used in
manusfacture of containers. Low density PE(LDPE) is soft and has a rather low
water vapor permeability, but high oxyg°en and aroma p ermeability and is
sensitive to fats and oils. Tm ~ 137 °C, Tg -130 to - 80 °C
Most polyethylene applications are in the areas of film, molding, cable and pipe
http://www.ciba.com/index/ind-index/ind-pla/ind-pla-polymersandpolymerprocessing/ind-pla-pol-polyethylene.htm
29
Properties: PP has a high degree of crystallinity(isotactic) or high
amorphous(atactic). The Tm, mechanical properties and transparency
are related to the crystallization, is a good insulator. PP is resistant to
attack by polar chemicals, such as, soap, alcohols and its water
absorption is very low, it reserves double duty as a plastic and as a
fiber. Tm ~ 180 °C, Tg ~ -17 °C.
The textile application is one of the largest polypropylene markets in size, being above
1700 kT in 2004 in Western Europe.
Dishwasher, safe food containers, indoor and ourdoor carpets (easy to make colored PP
and doesn’t absorb water).
http://www.totalpetrochemicals.biz/content/documents/143_b2_5_polypropylene_for_fibre_applications.pdf
30
5
PVC is useful plastic because it resists to fire and water. It is used to
make raincoats and shower curtains and water pipe. PVC is
commonly used in the construction sector, for example in window
frames and shutters, pipe cabling and coating, etc.
High amorphous ~11% crystallinity, Tg ~84 °C
PMMA is a clear colorless polymer, used extensively for
optical application. It is an amorphous thermoplastic, that is,
hard and stiff. PMMA has a good stability against UV
radiation, but it has poor chemical resistance.
PS is a inexpensive and hard plastic insulator, used in toys, the housings
of things like hairdryers, computers and kitchen appliances
Tm ~270 °C, Tg ~100 °C
31
1.6 Statistical molar mass (the mass of one mole)
Monodisperse
32
Molar mass dependence of the equilibrium
melting point of oligo- and polyethylene.
The sample is monodisperse if all polymers in a given sample
have the same number of monomers.
M=nMmon
Where n is the number of monomers in a polymer molecule, is the
degree of polymerization, Mmon molar mass of monomer,
M the molar mass of a polymer
Polydisperse
The sample is made up of individual
molecues that have a distribution of
degree of polymerization (depends on
synthetic method)
The molar mass distribution ranges over three
to four orders of magnitude for many polymers
33
Average molar mass
The z-average is given by:
The most commonly used averages are defined as follows.
The number-average is given by:
Mn =
∑N
i
Mi
i
∑N
34
M z ==
∑N
i
M i3
i
M i2
i
∑N
i
= ∑ ni M i
i
The viscosity-average is given by:
i
i
where Ni is the number of molecules of molar mass Mi, and ni is the number
fraction of those molecules.
The weight-average is given by:
Mw =
∑W
i
Mi
i
∑W
i
i
=
∑N
i
M i2
i
Mi
i
∑N
= ∑ wi M i

 ∑ N i M i1+ a
Mv = i

 ∑ Ni Mi
 i






1
a
i
i
where a is the exponent in the Mark-Houwink equation. It takes values
between 0.5 and 0.8 depending on the combination of polymer and solvent.
where Wi is the mass of the molecules of molar mass Mi, and wi is the mass
fraction of those molecules.
35
36
6
The correlation of Mn, Mw, Mz and Mν
A polymer sample consists of a mixture of three
mondisperse polymers with molar masses 250000,
300000 and 350000g/mol in the ratio of 1:2:1 by number
of chains, calculate Mn, Mw and Mw/Mn.
Solution:
Let the total number of chains with molar mass
250000g/mol be N, then
Mn≤Mv ≤Mw ≤Mz
All these averages are equal only for a perfectly monodisperse
polymer.
In all other cases, the averages are different:
M n <M v <M w <M z .
The viscosity average is often relatively close
to the weight average.
Standard deviation (σ) and Polydispersity index
Mn=(N×250000+2N×300000+N×350000)/(N+2N+N)=300000g/mol
Mw=…………………=304200g/mol
Mw
Mn
The breadth of the molar mass distribution, measuring how widely
spread the values i a data set. If the data points are close to the
mean, then σ is small.
Mw>Mn
Mw/Mn=1.014 (polydispersity index)
σn
Mn
=
Mw
−1
Mn
37
Experimental techniques for molar mass determination
38
1.7 Thermal transitions and physical structures
The logarithm of the relaxation modulus (10 s) as a function of temperature for
semicrystalline (isotactic) polystyrene and fully amorphous (atactic) polystyrene
in three "versions": low molar mass uncrosslinked, and high molar mass
uncrosslinked and crosslinked.
39
40
7