Year: 2010
Type: article
Abstract: We consider a crosslinked polymer blend made of two polymers of different chemical nature.We suppose that such a system incorporates small colloidal particles, which prefer to be attracted by one polymer, close to the spinodal temperature.This is the so-called critical adsorption.As assumption, the particle diameter, d 0 , is considered to be small enough in comparison with the size of microdomains (mesh size) ξ * ∼ an 1/2 , with a -the monomer size and n -the number of monomers between consecutive crosslinks.The critical fluctuations of the crosslinked polymer mixture induce a pair-potential between particles located in the non-preferred phase.The purpose is the determination of the Casimir pair-potential, U2(r), as a function of the interparticle distance r.To achieve calculations, use is made of an extended de Gennes field theory that takes into account the colloid-polymer interactions.Within the framework of this theory, we first show that the pair-particle is attractive.Second, we find for this potential the exact form: U2(r)/kBT = -AH(d0/r) 2 exp(-r/ξ * ) -BH(d0/r) 4 exp(-2r/ξ * ), with the known universal amplitudes AH > 0 and BH > 0 (the Hamaker constants).This expression clearly shows that the pair-potential differs from its homologue with no crosslinks only by the two exponential factors exp(-r/ξ * ) and exp(-2r/ξ * ).The main conclusion is that the presence of reticulations reduces substantially the Casimir effect in crosslinked polymer blends.
Source: Acta Physica Polonica A
Institution: University of Hassan II Casablanca
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W836263232