Surface-initiated RAFT polymerization of NIPAM from monolithic macroporous polyHIPE

Abstract

Amino-functional macroporous monoliths from polymerized high internal phase emulsion (polyHIPE) were surface decorated with chain transfer agents (CTAs) for Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization. Surface initiated RAFT polymerization of N-isopropylacrylamide resulted in a dense coating of PNIPAM on the polyHIPE surface. Through addition of free CTA the amount of the PNIPAM grafted to the monolith could be modulated corresponding linearly to the molecular weight of the free polymer chains. Scanning Electron Microscopy (SEM) analysis suggests a homogeneous polymer coating throughout the interior pores of the monoliths. The PNIPAM coated polyHIPEs were rendered hydrophilic displaying faster water uptake with increasing amount of grafted PNIPAM. Considering the high flexibility RAFT polymerization offers in the choice of monomers, simplicity of reaction and absence of any catalyst this approach opens a convenient route to highly functional polymeric monoliths.