New biodegradable and thermoresponsive polymers based on amphiphilic poly(asparagine) derivatives

New biodegradable and thermoresponsive polymers based on amphiphilic poly(asparagine) derivatives have been developed. They showed a sol-gel-sol phase transition. In particular, not only a phase transition behavior but also a lower critical solution temperature (LCST) was observed in the polymers with N,N-dimethylaminopropyl groups as the hydrophilic side chains. The LCST and a sol-gel-sol phase transition temperature could be precisely controlled by changing the composition ratio and kind of the hydrophobic and the hydrophilic groups of the side chains in the polymers. These polymers are expected to be applicable for controlled release of drugs, tissue engineering, and others.