High transition temperature shape memory polymers (SMPs) by telechelic oligomer approach

Abstract

This work describes the synthesis and comparative shape memory properties of cross-linked networks derived from epoxy and cyanate ester monomers containing polyether oligomers as reactive shape memory segments. The hydroxy telechelic oligomers viz. polyethyleneglycol (PEG), polypropyleneglycol (PPG), and polytetramethyleneglycol (PTG) are reacted with epoxy–cyanate ester matrix resulting in shape memory polymers with high transition temperatures. The soft oligomer segments act as flexible linker unit which interconnect oxazolidone, isocyanurate and triazine ring structures in the cross-linked polymer. The resultant cyclomatrix SMPs exhibit high transition temperatures 132, 178 and 161°C respectively for PEG, PPG and PTG integrated SMPs. The Eg/Er ratios are increased in the order PEG<PTG<PPG. The PTG and PPG based SMPs show shape retention of 99% and shape recovery of >98% with recovery time <100s. All the SMPs display good thermal stabilities (both inert and oxidative) above 275°C.