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

Thursday, May 22, 2014 - 14:00 to 15:00

Seminar Room C210, Level C, Centre Bldg.

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)

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