Supramolecular polycationic hydrogels with high swelling capacity prepared by partial methacrylation of polyethyleneimine

Abstract

Methacrylation of branched polyethyleneimine (PEI) was performed to generate modified polycationic macromolecules that self-assemble in water into highly swollen supramolecular hydrogels with tunable hydrophilicity and microstructure. The properties of the supramolecular hydrogels, in terms of swelling and porosity, were controlled during synthesis by the extent of methacrylation of the starting PEI macromolecules. The methacrylation reaction was conducted under several conditions, and the methacrylated PEI (PEI-MA) molecules were investigated by FTIR and NMR to relate the reaction parameters to the amount of methacrylate moieties on the modified polymer. The hydrogel morphology and its dynamic nature arising from the non-covalent interactions among the PEI-MA macromolecules were characterized by small-angle X-ray scattering (SAXS) and fluorescence microscopy at different temperatures, which enabled visualization of the large interconnected microcavities of the supramolecular gel network.