Preparation, structure, and properties of trimethylpentanediol modified polycaprolactone based dendritic shape memory polyurethane

Shape memory mandrel is more and more used in industrial production field. In order to obtain high strength and high precision polymer based products, shape memory mandrel has been widely concerned. Poly(ε-caprolactone) (PCL) is a semi-crystalline polymer. Because of its good degradability and shape memory effect, PCL is considered as an important raw material for the preparation of shape memory mandrel. In this paper, a shape memory polyurethane with a dendritic topological structure was synthesized by molecular cross-linking of poly(ε-caprolactone) diol and 2,2,4-trimethyl-1,3-pentanediol (TMPD). The shape memory polyurethane (SMPU) was characterized by Fourier-transform infrared spectroscopy, gel permeation chromatography, X-ray diffraction spectroscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, shore A durometer test, and shape memory analysis. The results showed that all the active groups were involved in the reaction, and the crystallinity of the prepared SMPU decreased with the decrease in PCL content. The shape memory effect of SMPU was influenced by PCL and TMPD contents. When the molar ratio of PCL and TMPD in SMPU is 1:3, SMPU has the best shape memory effect. Its shape fixation ratio and shape recovery ratio are 100%, shape memory recovery time is 153.3 s, and hard segment content is 44.85%. In conclusion, PCL based shape memory polyurethane has potential application in mandrels and needs further research.