Triple-shape polymers (TSPs) are a growing subset of a class of smart materials known as shape memory polymers. TSPs can store one permanent and two metastable shapes. We describe a novel TSP system, comprised of both permanent covalent crosslinks and reconfigurable hydrogen bonding crosslinks, which enables broad and independent control of both glass transition temperature (Tg) and crosslink density. Triple shape properties arise from the combination of (meth)acrylate copolymers and the dissociation of self-complimentary hydrogen bonding moieties. Specifically, ureidopyrimidone methacrylate and a novel monomer, ureidopyrimidone acrylate, were copolymerized with methyl acrylate, butyl acrylate and bisphenol a ethoxylate diacrylate. Control of Tg from 10-70 °C was demonstrated; concentration of hydrogen bonding moieties was varied from 0-40 wt%; concentration of the diacrylate was varied from 0-30 wt%. The effects of varying concentration of each crosslink type were observed through dynamic mechanical analysis, differential scanning calorimetry, and uniaxial tensile testing.
展开▼
