The Synthesis And Properties Study Of Medical Shape Memory Polyurethane

Shape memory polymer is a novel smart material which has great developmentpotential. Since shape memory polymer have excellent properties such as low-cost,high deformable ability, low-density, controllable performance and variety ofdrivers, it has become one of the hottest field of the smart materials.Conventional polyurethanes (PU) exhibit poor water resistance, thermalstability, which limits the application of polyurethane materials. On the other hand,Poly (dimethyl siloxane)(PDMS) systems have excellent properties including lowsurface energy and biocompatibility. Nowadays, researchers take their eye onPDMS modified polyurethanes. These copolymers not only have better heatresistance, mechanical properties and lower temperature polysiloxanes themselvesbut also have better mechanical strength and low-density than polyurethanes.A new kind of thermoplastic polyurethane containing silicone was investigatedin this study. A series of polyurethanes with shape memory performance weresynthesized by solution-polymerization. The chemical compositions, structures,bulk and surface properties were investigated by using infrared surface quantitativeanalysis technique (FTIR-ATR), surface contact angle, stress–strain analysis, XRD,SEM, DSC, TGA and dynamic mechanical thermal analysis (DMA). It was shownthat the contact angle increased swiftly with raising PDMS content, indicating thatwater resistance ability improved with increasing PDMS content. The memoryperformance was increased as the molecular weight of soft segment. Physicalcrosslinking was improved as hydrogen bond strengthens and further enhancespolymer mechanical properties. The main work is summarized as follows:The degree of reaction of different solvents was compared. The mixed solutionof DMF and dimethyl sulfoxide was chosen on the consideration of interfacialreaction. PDMS was successfully added to the polyurethane main chain by pre-polymerization reaction. Series shape memory polyurethanes whose glass transitiontemperature range from28.2℃to57.5℃were gained by controlling the molecularweight and content of the soft segment.The shape recovery rate of SMPU whose soft segments molecular weight was4000was greater than95%and the shape recovery time was only23s at thetemperature of90℃. The entropy change of the shape memory material was thereason why shape memory polymer can spontaneously shift from the glassy state torubbery state changes from the perspective of the thermodynamics of materials.POSS particles were added in the polyurethane material. The dispersion of POSSparticles in the polyurethane matrix, influence of polyurethane matrix crystallization, mechanical properties and heat resistance were studied. The resultsshow that when the POSS particles were in the range of1%wt to5%wt, thepolyurethane thermodynamic properties was greatly improved.The novel shape memory polyurethane could be driven by de-ionized waterand organic solvent. Physical swelling effect and chemically conjugated interactionwas introduced to confirm the solvent-driven shape memory polyurethane. Thebiomedical predict use was discussed by biomedical degradation experiment. Thewater resistance ability was dramatically increased by adding silicone chain. A self-demolition buckle was designed to use in the field of recovery of waste electricalproducts and drugs active release.