A Combined Physical–Chemical Polymerization Process for Fabrication of Nanoparticle–Hydrogel Sensing Materials

Abstract

A new type of light diffracting hydrogel composite film consisting of nanoparticles and polymer has been fabricated through a combined physical–chemical polymerization process. In this fabrication approach, polymers with ionic functional groups for molecular recognition were successfully incorporated into a hydrogel of colloidal photonic crystals. We first embedded crystalline colloidal arrays into a nonionic polymer hydrogel by a physical freeze–thaw process using a formulation that contained poly(vinyl alcohol), dimethyl sulfoxide, water, and monodispersed polystyrene nanoparticles. Then, a second ionic polymer network, which interpenetrates into the first polymer network, was formed through a photochemical polymerization process. During the formation of the second polymer network, functional groups for molecular recognition were introduced. Finally, the physically cross-linked nonionic polymer network was removed by hydrothermal dissolution, leaving the chemically cross-linked ionic polymer network int...