Fabrication of Poly(methyl methacrylate)-block-poly(N-isopropylacrylamide) Amphiphilic Diblock Copolymer on Silicon Substrates via Surface-Initiated Reverse Iodine Transfer Polymerization

摘要

Amphiphilic diblock copolymer on silicon substrates were synthesized via surface-initiated reverse iodine transfer polymerization (RITP) technique. The silicon substrates (Si (111) surface) were modified with the azo groups, which were introduced by the treatment of Si (111) surface with 4,4'-azobis (4-cyanopentanoic acid). The poly(methyl methacrylate) (PMMA) were then prepared under RITP conditions from the Si (111) wafer. The synthesis of amphiphilic diblock copolymer was carried out on Si-g-PMMA substrate by sequential addition of monomer N-isopropylacrylamide (NIPAM). The observed narrow molecular weight distributions (M_w/M_n), linear kinetic plots, and linear plots of molecular weight (M_n) versus monomer conversion indicate that the chain growth from the silicon substrates is a controlled process with a "living" characteristic. The ellipsometry and contact angle results indicated that the MMA had grafted from the surface of the silicon substrates successfully and the graft layer was well defined. The structure of the polymer and the ability to extend the chains were characterized and confirmed with the surface sensitive techniques such as X-ray photoelectron spectroscopy and atomic force microscope.