Optically active thermosensitive amphiphilic polymer brushes based on helical polyacetylene: preparation through 'click' onto grafting method and self-assembly

摘要

Optically active, thermosensitive, and amphiphilic polymer brushes, which consist of helical poly(N-propargylarnide) main chains and thermosensitive poly(N-isopropylacrylamide) (PNIPAm) side chains, were prepared via a novel methodology combining catalytic polymerization, atom transfer radical polymerization (ATRP), and click chemistry. Helical poly(N-propargylamide) bearing a-bromoisobutyryl pendent groups was synthesized via catalytic polymerization, followed by substituting the -Br moieties with azido groups. Then, alkynyl terminated PNIPAm formed via ATRP was successfully grafted onto the azido func-tionalized helical polymer backbones via click chemistry, providing the expected polymer brushes. GPC, FT-IR, and ~1H-NMR measurements indicated the successful synthesis of the novel amphiphilic polymer brushes. UV-vis and CD spectra evidently demonstrated the helical structures of the polymer backbones and the considerable optical activity of the final brushes. The polymer brushes self-assembled in aqueous solution forming core/shell structured nanoparticles, which were comprised of optically active cores (helical polyacetylenes) and thermosensitive shells (PNIPAm).