Matrix-Modulated Swelling of a Polymer Brush

We have measured, using nuclear-reaction analysis, the concentration depth profiles of polymer brushes consisting of end-tethered deuterated polystyrene tails within a polystyrene homopolymer, as a function of the surface coverage σ of tails and of the degree of polymerisation P of the polymer matrix. We find that the onset of brush swelling is shifted to higher σ values at higher P as expected from theory. Within the range of our parameters the L (σ) and L ( P ) variations are consistent with predictions of scaling and mean-field models, where L is the effective brush thickness.