Surface-tethered polymers in polymeric matrices

Abstract

Recently Budkowski et al. used nuclear reaction analysis to study polymer brushes consisting of end-tethered deuterated polystyrene tails within a polystyrene homopolymer matrix. They measured the concentration-depth profile as a function of the surface coverage a of tails and the degree of polymerisation of the matrix. For the matrix with the largest degree of polymerisation, the variation of the effective brush thickness L with σ can be fitted by the apparent power law L ∞ σ q with q=0.54±0.06. This scaling law is not expected theoretically for surface-tethered polymers exposed to a polymeric matrix consisting of chemically identical chains (χ=0, where χ is the interaction parameter). In the present note we would like to propose an explanation based on the fact that mixtures of deutterated and protonated polystyrene chains are characterized by a small (but non-zero) value of χ