Seminar on Theory of colloidal stabilisation by unattached polymers by Mr. Alexey Shvets, Thu 22 May 14:00 @ C210 Seminar Room

Date

2014年5月22日 (木) 14:00 15:00

Location

Seminar Room C210, Level C, Centre Bldg.

Description

Dear all, 
 
 
 
We would like to invite you to a seminar by Mr. Alexey Shvets on Thu 22 May. 
 
 
Date/Time:   Thu 22 May 14:00 - 15:00 
Venue:          Seminar Room C210, Level C, Centre Bldg. 
Title:            Theory of colloidal stabilization by unattached polymers
Speaker:       Mr. Alexey Shvets, Institut Charles Sadron, Université de Strasbourg, France
 
Abstract: 
 
Dealing with colloidal dispersions, one of the most important tasks is to prevent particle
aggregation due to van-der-Waals forces. Nowadays the stabilisation is mainly controlled by
electrostatic and/or sterical interactions. Colloidal dispersions may also be stabilised by
addition of a certain amount of free non-adsorbing polymer. While the first two mechanisms
are well understood the latter one – named depletion stabilisation - still raises many questions.
The established theoretical models describing this polymer-induced (PI) stabilisation are
oversimplified and are not able to predict the dependence of the PI on solution parameters.
To improve the understanding of PI stabilisation a new theoretical model was proposed.
Based on self-consistent field theory (SCFT), numerical calculations were performed for the
thermodynamic potential as a function of the distance between colloidal surfaces. It could be
shown that, under certain conditions of the polymer solution, there is a repulsive barrier of
interaction between two solid surfaces [1].
Furthermore, these theoretical studies have shown that the repulsive barrier depends strongly
on the size of the particles and the polymer. In the case of hard sphere particles (HS) and
non-adsorbing polymer an influence of the repulsion on the thermodynamic behaviour of a
colloid-polymer mixture is predicted to be only relevant in the case of large particles (R ≥
200nm) and much smaller polymers (Rg < 25nm).
In addition, the model of HS was further improved introducing adsorbed surfaces and soft
shell layers which were considered along with free polymers. These improved models are able
to be experimentally investigated and the first steps give hope to confirm the effect.
 
 
1.  A. A. Shvets, A.N. Semenov “Effective interactions between solid particles mediated by free polymer in
solution”, J. Phys. Chem. , 139  054905, (2013).
 
 
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We welcome all to attend the seminar.
 
 
Best regards, 

 


Momoko Zamami 
Biological Physics Theory Unit
Okinawa Institute of Science and Technology Graduate University
1919-1 Tancha, Onna-son, Okinawa 904-0495 JAPAN
Tel: +81-98-966-2116 (Direct) +81-98-966-8711 (Main)
http: //www.oist.jp

 

Sponsor or Contact: 
Biological Physics Theory Unit
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