1. – R2 = 1/T2. (1)
• R2sp is obtained through normalization with respect to a
reference sample (R°2)
– R2sp = (R2/R°2) – 1 (2)
• Plotting the measured R2sp value against (mass of
particles) / ( mass of particles + solvent + dispersant)
particle as % weight will yield a straight line
• It has been shown that the adsorption of polymer onto
the particle interface can bring associated solvent
molecules to the surface or bind the water at the surface
more tightly, enhancing the relaxation rate constant and
thus producing a larger R2sp value and an enhancement
in the gradient
• Non-adsorbed loops and tails, as well as non-adsorbed
polymer, have no effect on the relaxation rate
Aim: To develop and validate a novel analytical approach to quantify the adsorption of polymeric dispersants
onto particle surfaces, by gaining a better understanding of both the capabilities and limitations of the 13.5 MHz
XiGo Nanotools Acorn NMR machine.
Team members:
Student– Adam Marks Supervisor– Dr. Beth Green
The contents of this poster are confidential and are for internal use only. No part of this poster should be copied in anyway.
• AkzoNobel is a Dutch multinational company which
specialises in:
– Decorative paints
– Industrial coatings
– Specialty chemicals
• The company operates in more than 80 countries, and
employs approximately 50,000
• Owner of multiple household name brands such as;
Dulux, Sikkens, Eka & Hammerite
• 13.5 MHz XiGo Nanotools Acorn Area bench-top
nuclear magnetic resonance (NMR) machine
• Low Field NMR Technique:
- Relaxation rate of the solvent is studied
- Unlike other NMR techniques which normally look
at the surfactant / dispersant particles specifically
- Measurements must be taken with and without
dispersant
- Surface adsorption is inferred from the change in
the rate of relaxation upon addition of dispersant
- Proton spin spin relaxation (T2) values recorded
- An increase in available surface area leads to an
increase in relaxation rate
- A deuterated solvent is not needed- the protons in
the solvent are studied
Polymer adsorption investigation:
• At pH 9 close to the IEP the non-ionic dispersant adsorbs
more strongly than the anionic dispersant, this is reversed at
pH 5 where the particle is less negative and this repulsion is
reduced
AkzoNobel Background
Instrumental Technique Theory
• Technique has been confirmed to show the presence/absence of
polymer adsorption for multiple particle surfaces
• Adsorption is dependant upon the isoelectric point, patchiness of
the inorganic coating and morphology of the surface
Results
• Colloid Science concerns the design, creation and
processing of complex fluids and ‘soft’ solids derived from an
understanding of the dispersion, rheology and molecular
associations of the systems involved
• At AkzoNobel, the focus is on:
– the formation, stabilization and characterization of
emulsions, dispersions and foams,
– controlling the flow behavior (rheology) of products
Particle (B)
y = 0.59x
Particle (A)
y = 0.66x
Particle (C)
y = 0.65x
Paritlce (D)
y = 0.73x
Particle (C) + Disp.(A)
y = 0.84x
Particle (A) + Disp.(A)
y = 0.76x
0
1
2
3
4
5
6
7
0 1 2 3 4 5 6 7 8 9
R2sp
Particle / %w/w
• Initial results confirm
the validity of the solvent
relaxation NMR
technique for future use
in colloidal science
• Data is both
reproducible and
consistent with the
relevant theory
Particle Without Dispersant
y = 4.59x
Particle With Dispersant
y = 7.33x
0
10
20
30
40
50
60
70
0 2 4 6 8
R2sp
Particle/ %w/w
Particle (A)
y = 0.66x
Anionic Dispersant
y = 0.82x
Non-Ionic Dispersant
y = 0.77x
0
1
2
3
4
5
6
7
8
0 2 4 6 8 10
R2sp
Particle / %w/w
Particle (A)
y = 0.69x
Anionic Dispersant
y = 0.76x
Non-Ionic Dispersant
y = 0.80x
0
1
2
3
4
5
6
7
8
0 2 4 6 8 10
R2sp
Particle / %w/w
R2sp vs %w/w at pH 5 R2sp vs %w/w at pH 9