Synthesis and characterization of well-defined polymers with various architectures prepared by controlled radical polymerization

Abstract

This thesis deals with synthesis and characterization of well-defined polymers with various architectures. The polymers having complicated structures were prepared by combination of controlled radical polymerization (CRP) technique. Linear-hyperbranched (L-HB) block copolymer, polystyrene-block-poly(2-(2-bromopropionyloxy)ethyl acrylate) (PS-b-PBPEA), was synthesized by the combination of self-condensing vinyl polymerization (SCVP) and atom transfer radical polymerization (ATRP). The linear-linear analogue L-L PS-b-PBPEA was also synthesized by sequential reversible addition-fragmentation chain transfer (RAFT) processes for the comparison. The significantly smaller hydrodynamic volume of L-HB compared to L-L PS-b-PBPEA was observed in GPC chromatograms. The Br end groups of L-HB PS-b-PBPEA were further transformed to amine via azide modification. The resulting polymers were fabricated as a thin film, and their surface properties were investigated. Microphase separation was clearly observed in AFM images. The contact angle was largely decreased after amino end modification that confirmed the end-group effect on surface energy overwhelmed the structural effect. Comb-coil block copolymer (CCBCP) poly(methyl methacrylate)-block-poly(2-(2-bromopropionyloxy)ethyl acrylate)-graft-polystyrene (PMMA-b-PBPEA-g-PS) was synthesized by the combination of RAFT and ATRP. The polymer exhibits vertically oriented cylindrical morphologies on various substrates that are driven by this architecture, which overcomes the interactions between the substrates and the polymer chains. The formation of vertically oriented cylindrical pores on patterned surfaces was also demonstrated. Star-shaped polymers, $[poly(methyl methacrylate)-block-poly(2-((2-bromoisobutyryl)oxy)ethyl methacry-late)-graft-poly(N-isopropylacrylamide)]_n$ $([PMMA-b-PBIEM-g-PNIPAM]_n$ (n = 2, 3, 4)) were synthesized by sequential ATRPs using multifunctional initiators. The architecture, molecular weight, polydispersi...