Biodegradable thermoset shape-memory polymer developed from poly(β-amino ester) networks

The purpose of this study was to develop a degradable thermoset shape-memory polymer from poly(beta-amino ester) (PBAE) networks. PBAE was chosen to be the crosslinker as it is biodegradable and has been projected as a potential material for biomedical applications. The low glass transition temperature of PBAE was increased to a biomedically relevant range using methyl methacrylate and methyl acrylate as the linear chain builders. The thermo-mechanical properties of the networks were tailored such that they exhibited onset of glass transition temperature in between the room temperature (22 degrees C) and the body temperature (37 degrees C). Free-strain recovery tests under heating and isothermal conditions were performed to quantify shape-memory behavior. Testing showed that sampled programmed at 10 degrees C initiated deformation recovery at a lower temperature and a faster rate as compared to programming at 60 degrees C. Higher thermal conductivity of water enabled the samples to recover faster in water than in air. Samples with higher PBAE crosslinking densities exhibited higher normalized mass loss under regular and accelerated conditions. The amount of water absorption in the networks also increased with the crosslinker concentration independent of the testing conditions. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012