Presented by
Dr. Daniel Hagmeyer
• Produktmanager
Kolloidanalytik
• Promovierter Chemiker
Das DUO
Stabino® / NANO-flex®
Inhalt
• Theoretischer Hintergrund zur Partikelladung
• Anwendungsbeispiele
• Was Kunden sagen
• Fragen und Antworten
What are Colloids?
clear
• Macromolecules in solution
– < 1nm – 10 nm
1 nm
• Particles dispersed in liquids
– < 1 nm – 10 µm
• > 20 nm  turbid
turbid > 20 nm
100 nm
Colloids
How do colloids behave?
• General tendency to agglomerate
– dipole - dipole interaction (Van der Waals)
– Adhesions forces
• Stability is guaranteed by having a repulsive surface
Stabilization of nanoparticles
 (A) electrostatic stabilization  we can measure
 (B) steric stabilization
 (C) electrosteric stabilization  we can measure
Any charged surface of an object – macromolecule, particle, wall – has the
potential to attract or repulse other charges
Charges, colloid interfaces interact with ALL
ions from the surrounding liquid
• Charges stabilize
• Charges interact with ions
from the liquid environment
• A change in chemical
environment can cause
stability to be better or worse.
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Interaction partners in liquids
❶ Smallest ions (pH & salt)
H+, OH- , Na+, Cl-, Ca2+ …
❷ Poly – electrolytes (PE)
= charged macromolecules,
100 to 1000 times bigger
❸ Particles
NH3+
ALL – that is the difficulty!!!
❹ Big surfaces
(glass with negative ions)
COH-
Repulsion / Attraction
• Ionic charges on every surface have the POTENTIAL to
repulse or attract charges
• Depending on the polarity of the interaction partner,
there is repulsion or attraction
Required for stability
How strong is …?
• Repulsion or attraction depends on the
amount of charges per surface area
DLVO-theory
repulsion energy ER
total energy Et
attraction energie
EA
Energy =
potential
How to measure the strength of
repulsion or attraction?
1. The magnitude of Zeta potential
2. The consumption of calibrated polyelectrolytes
for the Total Charge determination
In general, the higher Zeta potential and
the consumption of polyelectrolytes
 the better is the stability
Particle Interface Potential / zeta potential
Closer look
Mobile
counter ions
Shear plane
Creating zeta potential - Closer look
Mobile
counter ions
Moving force:
Electric field (common)
Fluid stream
Shear plane =
location of the zeta potential
Measurement methods for Zeta Potential
• Electrophoretic mobility
– Particles in an electric field
µe = vE-1
– zeta potential (ZP, z) calculated ZP ~ µe
• streaming zeta potential (SZP)
– Liquid moves, particles immobilized (more details later)
• colloid vibration current (cvi)
– Movement of the liquid with ultra sound
Difficulties reported
• ZP Measurements not repeatable
 chemical environment changes
• Problems with bubbles
• Problems with the optical properties of the sample
• Problems with dilution
• Titrations very slow and complicated – therefore avoided
2 methods to measure - Zeta Potential (ZP)
Immobilized particles at a
plane Teflon® - surface
„plane“
surface
Ev
Fluid stream 
Streaming zeta potential
(SZP)
electric field 
Electrophoresis zeta
potential
Control the environmental influence by
Mix & measure
pH-, salt- or
Changing the
environment of the
particles by defined
addition of
Polyelectrolyte solutions
SP = k · ZP
-
ZP ~ (measured potential)
SP /
ZP
+
Immobilized
particles
SP =
streaming potential
K=
system constant
ZP =
zeta potential
Why titrations?
Many external parameters influence the ZP/stability
measured
Titration (pH)
potential
IEP & point of zero charge
Coagulation
Agglomeration
Aggregation
Coalescence
pH, additives
(polyelectrolytes),
salt
Role of the Polyelectrolytes (PE)
• PE solutions can be manufactured in accurately known
charge concentrations
– 1N solution carrying 1 mol/L of elementary charges =
9760 C (Coulomb)
• It will coat the surface of particles and change the „zeta“
potential  method to measure the surface charge
PE Titrations are only possible with streaming potential
method
Calibration of the potential with suspensions
and polyelectrolytes
• Zeta Potential (ZP) with a standard suspension of known
Zeta potential
• Streaming potential (SP) with a standard polyelectrolyte
solution of known streaming potential
During a measurement,
ZP / SP are displayed simultaneously
Multi-parameter titrations  SOPs
 Titrations
 pH
 Isoelectric Point Measurements
 Stable pH Areas
 Poly Electrolyte (PE)
 Coatings with polyelectrolytes
 Stability measurements of dispersions
 Ionic activity / Charge density
 Salt
 Conductivity
 Size
RESULT in general:
Predicting the status of
colloidal systems
(IEP, stable zones, stability)
Stabino set-up
If the application requires … back titration 
Application (pH): 3D Plot of Al2O3 (W630)
Application (pH): Titration of Lysozyme
polyelectrolyte titration (PE)
Results:
Ionic activity
charge density [Cg-1]
Coating efficiency
Application (PE): oil in water emulsion
Additive for construction industry
10
0
0
zeta potential / mV
-10
0,5
1
1,5
old
-20
fresh
-30
-40
-50
-60
-70
-80
-90
2
volume / mL
2,5
Predicting stability of filtered beers (PE):
Following the artificial
aging method with
Stabino
TITZE, J., ILBERG, V., JACOB, F., PARLAR, H., 2008: Einsatzmöglichkeiten der
Ladungsttrationsmethode zur
Beurteilung der chemisch-physikalischen Bierstabilität, Teil 2. Brauwelt 148, Nr. 23, S.
624-527.
Application: Salt titration of Al2O3 with KCl
In-situ Size measurement
180° heterodyne back scattering (DLS)
Detector
Homodyne
Laser
Heterodyne
Scattered &
reflected
light
Laser in &
reflected laser
Scattered light
from particles
K: colloid D: detector O: imaging optics
R: partial reflecting surface
Size & concentration
0.01 – 40 vol%
dip-in size measurement –
critical coagulation point
Application: three modal latex beads mixture
Dia / nm
measured
Vol %
measured
Dia /nm
theoretical
Vol %
theoretical
83.9
11.7 %
95.6
33.74 %
711
76.8 %
746
63.22 %
3790
11.5 %
4760
3.04 %
711 nm
83.9 nm
3790 nm
Application: high resolution and differentiation
200 nm
100 nm
Conclusions
 Zeta potential and streaming potential in one
measurement
 Size range for charge: 0.3 nm to 300 µm
 Speed: Fast formulation tool
 Wide concentration range 0.01 to 40 vol.%
 Potential at conductivities  300 mS cm-1
 3D Particle Charge Mapping
 Charge density
 NANO-flex® in-situ size (0.3 nm – 6.5 µm)
Customer Feedback…
• “The best software we ever have experienced.”
• “Easy to learn, easy to use, easy to clean.”
• “Precise and Reliable”
Vielen Dank
für Ihre
Aufmerksamkeit
Das DUO
Stabino® / NANO-flex®