Structure of polymer solutions containing fumed silica - art. no. 041402

Small angle neutron scattering is employed to estimate the interactions in complex multicomponent systems. The method is applied to describe a ternary system, poly(dimethyl siloxane) toluene with silica filler particles. Cont rast variation by solvent deuteration is used to distinguish the three diff erent partial structure factors of filled polymer samples, S-pp(q), S-pf(q) , and S-ff(q), where the subscripts p and f refer to polymer and filler. Th is procedure allows changes to be detected in the distribution of the polym er close to the solid surface. Independent dynamic light scattering measure ments are used to validate the method, A comparison is made between the beh avior of different filled poly(dimethyl siloxane) PDMS samples. It is found that the polymer distribution is perturbed in the vicinity of the solid su rfaces. In the case of weak interactions, the solvent removes the polymer a lmost completely from the filler particles, while, when the interaction is strong, the surface remains covered.