Self-Assembly of a Condensation Homopolymer: With an Application in Fractionation

Abstract

Self-assembly constitutes a versatile and important pathway to the emergence of complexity. The conventional wisdom in the polymer regime typically focuses on the utility of either main chain-main chain block copolymers or main chain-side chain addition polymers. Herein, the self-assembly of a condensation homopolymer is reported, presenting a distinct alternative to the conventional regime. In particular, a unique inverse main chain-side chain amphiphilic polymer architecture has been designed into a squaramide condensation homopolymer, with a polar solvophilic main chain and a nonpolar solvophobic side chain. This architecture provides a hitherto elusive contrast to the currently dominating canonical amphiphilic polymer architecture for addition polymers, with a nonpolar solvophobic main chain and a polar solvophilic side chain. As such, the squaramide condensation homopolymer synthesized herein has showcased the intriguing self-assembly into primary micelle and compound micelle constructs in a solvent-nonsolvent medium, allowing for fractionation into varied chain length fractions, each with a narrow polydispersity. The superior efficiency and accuracy observed in the four-step sequential fractionation as well as one-step fractionation for five as-synthesized chain lengths and six degradation-engendered chain lengths promise self-assembly fractionation as a powerful mechanistic framework for the precision targeting of diverse polymer structures and functions.