Smart Nanofibers from Combined Living Radical Polymerization, "Click Chemistry" and Electrospinning

A simple method for preparing solvent-resistant nanofibers with a thermal surface has been developed by the combined technology of reversible addition fragmentation chain-transfer(RAFT) polymerization atom transfer radical polymerization (ATRP), electrospinning, and "click chemistry". Initially, well-defined block copolymers of 4-vinylbenzyl chloride (VBC) and glycidylmethacrylate (GMA) (PVBC-b-PGMA) were prepared via RAFT polymerization. Electrospinning of PVBC-b-PGMA from a solution in tetrahydrofuran gave rise to fibers with diameters in the range of 0.4-1.5 mu m. Exposure to a solution of sodium azide (NaN3) not only affords nanofibers with azido groups on the surface but also leads to a cross-linking structure in the nanofibers. One more step of "click chemistry" between the PVBC-b-PGMA nanofibers with azido groups on on the surface (PVBC -b- PGMA(-N3)) and alkyne-terminated polymers of N-isopropylacrylamide (NIPAM) (PNIPAM(AT)), which were prepared by ATRP allows the preparation of a PVBC-b-PGMA nanofiber with thermal-sensitive PNIPAM brushes on the surface (PVBC-b-PGMA-g-PNIPAM). PVBC-b- PGMA nanofibers exhibit a good resistance to solvents and thermal-responsive character to the environment having a hydrophobic surface at 45 degrees C (water contact angle similar to 140 degrees) and having a hydrophilic surface at 20 degrees C (water contact angle similar to 30 degrees)