Synthesis and properties of temperature-responsive shape memory polyurethane with secondary crosslinked network structure based on LPO

Polyurethane has emerged as an excellent potential candidate for shape memory materials due to its microphase-separated structure with alternately connected hard and soft segments. In this study, SMPU of different molecular weights were prepared with poly(caprolactone) diol (PCL), hexamethylene diisocyanate (HDI), 1, 6-hexanediamine (HMDA), trimethylolpropane tris (3-mercaptopropionate) (TMPMP), and Dilauroyl peroxide (LPO). LPO as a chemical cross-linking agent can induce secondary cross-linking, which leads to the formation of a strong and stable secondary cross-linking network, and this network can be transformed into a supplier of internal stresses, so that the network exhibits excellent bidirectional shape memory effects. The effects of thermal and shape memory properties were investigated by TGA, DSC and DMA tests, the phase transition temperature of the SMPU was studied and the shape recovery process was recorded. The results show that the SMPU synthesized by PCL_2k has good shape memory performance, with a reversible strain of up to 16.1 %, and the average shape fixation and recovery rates of 92.83 % and 99.98 %, respectively, with good shape memory performance, which is expected to show a wide range of application prospects and value of use in the fields of smart fabrics, biomedicine, sensing drive, aerospace and so on.