Synthesis and characterization novel chemically cross-liked shape memory polymers based on polycaprolactone and hydroxyprpoyl cellulose

Shape-memory polymers (SMPs) have the ability to recover their original shape from a temporary shape when they are exposed to an appropriate stimulus such as heat, light, electric field, magnetic field, or moisture. In recent years, SMPs have gained an increasing amount of attention for their medical applications, such as smart sutures, vascular stents, esophageal stents,and tissue engineering scaffolds,and in drug delivery[1].Poly (caprolactone) (PCL)as a semicrystalline biodegradable polymeris one of the mostimportant polymer with relatively low melting temperatureand good mechanical properties. For biomedical applications,the biodegradability nature of the polymers and adjustment oftheir Tm around the human body temperature (37–39 °C) arethe essential key factors and a challenging field for researchers[2]. Hydroxypropyl cellulose (HPC) has been widely studied as biomedical or intelligent materials due to its nontoxicity, biocompatibility and high mechanical strength [3]. In this study, the chemically cross linked SMP films of PCL wereprepared in four steps. In the first step bulk polymerization ofPCL, was initiatedby ring-opening polymerization of ε- CL in the present of butandiol and using stannous octoate as catalyst. In the second step,after removing the moisture under nitrogen atmosphere, hexamethylene diisocyanate (HDI) was added on the obtainedpurifiedPCLdiols.The third stepwas performed by addingHPCsolution inCHCl3 to the reaction mixture (Figure1).In the fourth and final step, after obtaining a homogenized solution, the mixture was poured into a Teflon dish andleft atthe room temperature for 24 h. In order to more curing, dried film was placed in an oven at 80 °C for another 24h.The obtained SMP polymers were characterized and examinedusingFT-IR, 1H NMR, DSC, XRD,and tensile and SMP tests.