Synthesis of Poly(n-(2 Methacrylamide) Brushes by Interface-Mediated Raft Polymerization

Abstract

The synthesis of poly(N-(2-hydroxypropyl) methacrylamide) [poly(HPMA)] brushes is reported using an interface-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization on a silicon substrate. To produce a RAFT agent immobilized surface, 4-cyano-4-(propylsulfanylthiocarbonyl)sulfanyl pentanoic acid was reacted with 9-decen-1-ol to form a self-assembled monolayer. Poly(HPMA) brushes and free polymers of varied molecular weights between 10 100 and 48 500 g mol(-1) were then synthesized by RAFT polymerization. The chemical characterization of the modified surfaces was examined using atomic force microscopy, grazing angle-Fourier transform infrared and X-ray photoelectron spectroscopy, ellipsometry and water contact angle measurements. The average distance between grafting sites (D, nm) and grafting density (sigma, chains per nm(2)) of poly(HPMA) brushes calculated from the dry film thickness (h, nm) and the number-average molecular weight ((M) over bar (n)) of the free polymers were 1.3 nm and 0.52 chains per nm(2), respectively, indicating moderate density polymer brush formation.