Synthesis of CO2-Based Block Copolymers via Chain Transfer Polymerization Using Macroinitiators: Activity, Blocking Efficiency, and Nanostructure
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2018 American Chemical Society. Immortal copolymerization of epoxides/CO2 using macro-chain-transfer agent (macro-CTA) is a useful method to prepare CO2-based block copolymers for manufacturing high value-added materials. Despite a variety of CO2-based block copolymers that have been reported using distinct macro-CTAs, issues including catalytic activity and blocking efficiency for the immortal polymerization remain superficially understood. Here, we systematically studied the reaction activity and blocking efficiency by using various macro-CTAs (including PPG, PEG, and PS) in the presence of two classical catalyst systems ((BDI)ZnOAc and SalenCoTFA/PPN-TFA). By analysis of the gel permeation chromatograms via mathematical deconvolution, it comes to a conclusion that the size, nature, and ratio of [macro-CTA]/[Cat.] strongly influence the catalytic activity of the reaction and blocking efficiency for the resultant block copolymers. Thin film self-assembly of PS/PPC block copolymers was investigated, and the results were analyzed by SEM to ascertain the impact of blocking efficiency on nanoassembly.