COLLAPSE-STRETCHING TRANSITION FOR POLYMER BRUSHES - PREFERENTIAL SOLVATION

We have investigated by small-angle neutron scattering techniques the collapse-stretching transition of grafted poly(dimethylsiloxane) chains. Two ways have been used for inducing this transition: modifying the chemical composition in a binary mixture or changing the temperature in a given solvent around the theta-point. The first method reveals a spectacular preferential solvation effect, provided that the grafting density is high enough. The second method is more graduate: the thickness of the interface is a linear function of temperature in the range we have investigated.