Study of the synthesis and properties of polyurethane containing pyridyl units for shape memory

Abstract

In this study, 4,4′-diphenylmethane diisocyanate and polytetramethylene glycol were used to prepare a prepolymer, and 2,6-pyridinedimethanol (2,6-PDM) was then used as a chain extender to prepare a novel polyurethane (PDM/PUs). Gel permeation chromatography analysis shows that the molecular weight of PDM/PUs increases as the 2,6-PDM content increases. Fourier transform infrared spectroscopy analyses demonstrate that by increasing the 2,6-PDM content, PDM/PUs will form strong hydrogen bonds. The thermal analysis of PDM/PUs indicates that the initial decomposition temperature of PDM/PUs-03 is approximately 10 °C higher than that of PDM/PUs-01. Differential Scanning Calorimetry and Dynamic Mechanical Analysis analyses indicate that increases in the 2,6-PDM content produce significant enhancements in the glass transition temperature (T g) and the dynamic T g of PDM/PUs. Stress–strain tests indicate that 2,6-PDM can increase the maximum stress and Young’s modulus of PDM/PUs while reducing the elongation rate at break. The results of moisture absorption rate test indicate that when the 2,6-PDM content and ambient humidity increase, the water absorption rate of PDM/PUs increases. Moreover, PDM/PUs exhibits good shape recovery (>90 %).