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 cop olymers of poly(beta-deuterostyrene-b-2-vinylpyridine) (beta-DSVP) hav e been prepared by anionic polymerization. The mobility of the adsorbe d block copolymer on Cab-o-sil silica and gamma-Al2O3, swollen with to luene, was probed with deuterium NMR relaxation time measurements. We found that the styrene segments of these lower molecular weight copoly mers exhibited a lower mobility when adsorbed and swollen in toluene t han the corresponding polymer in solution. On this basis, the mobility of the styrene segments in this low molecular weight copolymer appear s to be intermediate between that of the strongly stretched chains in a higher molecular weight copolymer and randomly attached chains of ho mopolymers. This was probably due to a combination of a more compact s urface structure and styrene segments which were closer to the surface . There was only a small difference in the dynamics of the adsorbed po lymer 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 pyri dine segments on alumina.