Adsorption and Dynamics of Low Molecular Weight Poly(styrene-b-2-vinylpyridine) on Silica and Alumina in Toluene

Low molecular weight (ca. 10 000 g/mol) specifically-labeled block copolymers of poly(β-deuterostyrene-b-2-vinylpyridine) (β-DSVP) have been prepared by anionic polymerization. The mobility of the adsorbed block copolymer on Cab-o-sil silica and γ-Al2O3, swollen with toluene, was probed with deuterium NMR relaxation time measurements. We found that the styrene segments of these lower molecular weight copolymers exhibited a lower mobility when adsorbed and swollen in toluene than the corresponding polymer in solution. On this basis, the mobility of the styrene segments in this low molecular weight copolymer appears to be intermediate between that of the strongly stretched chains in a higher molecular weight copolymer and randomly attached chains of homopolymers. This was probably due to a combination of a more compact surface structure and styrene segments which were closer to the surface. There was only a small difference in the dynamics of the adsorbed polymer on the type of surface used (Cab-o-sil silica vs alumina). This small difference may be due to a stronger attachment of the vinyl pyridine segments on alumina