Visualizing the efficiency of rapid modular block copolymer construction

Abstract

The quantification of the efficient ultra-rapid modular synthesis of block copolymersviatwo-dimensional chromatography and a comparably accurate, low-cost deconvolution of size exclusion chromatography traces is reported. Cyclopentadienyl-capped poly(methyl methacrylate) (PMMA, 97% functionality) and a series of pyridin-2-yldithioformate-capped poly(isobornyl acrylate)s (PiBoA, 93–95% functionality) were synthesiszed via atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain transfer (RAFT) polymerization respectively. The corresponding block copolymers were generated by simply stirring a chloroform solution of PMMA, PiBoA and acidic catalyst for 10 min at ambient temperature. The crude block copolymer mixtures were directly analyzed by size exclusion chromatography (SEC), liquid adsorption chromatography at critical conditions (LACCC) and 2D LACCC-SEC to visualize the efficiency of the ultra rapid conjugation reaction. The quantitative analysis via the 2D LACCC-SEC yielded the composition of the block copolymer mixtures which were in excellent agreement with predicted values, thus indicating quantitative conjugation efficiency. In all cases, the crude block copolymer mixtures contained at least 94 wt% block copolymer. Furthermore, a low-cost deconvolution method that may be applied to conventional SEC traces was found to provide comparable composition data.