Postpolymerization synthesis of (bis)amide (co)polymers: Thermoresponsive behavior and self-association

A library of novel well-defined (bis)amide-based (co)polymers was prepared through postpolymerization modification of poly(pentafluorophenyl acrylate) with amines including ammonia and amide derivatives of amino acids. Products were characterized using a combination of NMR and FT-IR spectroscopies and size exclusion chromatography; results conformed to the expected structures obtained through quantitative conversion. The series of (bis)amide (co)polymers displayed rich phase behavior in aqueous solution such as thermoreversible gelation at low temperature and high concentration while other samples displayed inverse temperature dependent solubility (lower critical solution temperature (LCST)-type) behavior. A hydrophobically modified polyacrylamide copolymer displayed upper critical solution temperature (UCST) behavior in aqueous solution. Significantly, driven by polymer–polymer hydrogen bonding, copolymers self-associated into highly ordered, regular structures of several tens to hundreds of micrometers in size. Morphologies included sheet-like, rod-like and honeycomb-like structures and depended strongly on the chemical composition of copolymers. Governed by strong intra- and intermolecular hydrogen bonding between amide groups, a series of novel (bis)amide (co)polymers prepared by post-polymerization modification of an activated ester scaffold is shown to reversibly gel in water at low temperatures, display LCST or UCST behavior in water and to self-organize into large sheet-like or rod-like structures. [Display omitted] •(Bis)amide side chain (co)polymers with very strong hydrogen bonding capacity.•Novel thermoresponsive materials containing amino acid derivatives.•Aqueous LCST and UCST transitions.•Self-Assembly into very large ordered structures in dry state.