Amphiphilic comb-shaped diblock polymer brushes on Si(100) substrates via surface-initiated atom transfer radical polymerization

Amphiphilic comb-shaped 2-hydroxyethyl methacrylate-graft-poly(styrene)- block-poly(poly (ethylene glycol) monomethacrylate) (P(HEMA)-g-PS-b-P(PEGMA)) copolymer brushes, covalently tethered on Si(100) substrate, have been successfully prepared by (i) UV-induced hydrosilylation of 4-vinylbenzyl chloride (VBC) with the hydrogen-terminated Si(100) (Si-VBC surface), (ii) surface-initiated atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) to give the Si-VBC-g-P(HEMA) surface, (iii) coupling of 2-bromoisobutyryl bromide with the HEMA units via esterification to provide the comb-shaped macroinitiators (Si-VBC-g-P(HEMA)-R₃Br) for the subsequent ATRP, (iv) surface-initiated ATRP of styrene (St) to produce the Si-VBC-g-P(HEMA)-g-PS surface, and (v) the persisting of an active PS chain end can be used as the initiator for the subsequent ATRP of poly(ethylene glycol) monomethacrylate (PEGMA) to give the amphiphilic Si-VBC-g-P(HEMA)-g-PS-b- P(PEGMA) brush surface. The chemical composition and functionality of the silicon surface were tailored by the well-defined comb-shaped PS and P (PEGMA) brushes.