Study Of Shape Memory Properties And Biocompatibity Of Polyurethane/Graphene Nanocomposites

Shape memory polyurethane is a new kind of polymers with shape memory function. Because of wide restoring temperature, surpassingly mechanical properties, good biocompatibility and so on, it is widely used in construction, machinery, biological medicine and supplies. Now the research of SMPU focuses on a single performance, while few researches are done on its modification and application.A comprehensive research on preparation, modification and biocompatibility of SMPU has be done in this paper. First of all, the SMPU of different molecular ofsoft segment was prepared, its crystallization behavior, mechanical properties and shape memory performance was studied. In order to further improve the shape recovery rate and shape fixed rate, SMPU/graphenenanocomposites was prepared by noncovalent and situ polymerization. Its isothermal annealing time and temperature, shape fixed rate and shape recovery rate of graphene of different content were studied. The biocompatibility of SMPU of the different molecular weight of soft segment and different content of graphene by cultivating mice myocardial cells and cervical cancer cells.This paper has made some research results. The crystallinity was increased with the molecular weight of soft segment at the same hard segment content, which made shape fixed rate and shape recovery rate increasing gradually. The tensile strength was increased first and then decreased with the molecular weight of soft segment at the same tensile ratio. It reached the maximum when the molecular weight of soft segment is 4000.The crystallinity of SMPU/graphene composite materials was increased with the extension of time within 3h and changed weakly after more than 3h. The epitaxial crystallization phenomenon is more apparent when the isothermal annealing temperature is less than 28℃. The total crystallinity was increases with temperature rising, which made shape fixed rate and shape recovery rate increasing gradually. Specially, the total crystallinity was 31.1% and the shape fixed rate and shape recovery rate were 96.5% and 97% respectively when the temperature was 28℃. The total crystallinity of the composite material are higher than the pure SMPU at the same isothermal annealing condition. Especially, compared with the SMPU, the shape fixed rate and shape recovery rate increased by 14.3% and 6.5% respectively when graphene content is 1%.Through the cultivation and observation of the two kinds cells, it is found that the SMPU of the different molecular weight of soft segment are non-toxic. And two kinds of cells can adhere to these thin film and growth well. For the SMPU/graphene nanocomposites, the two kinds of cells can also adhere and growth. There is not change about the amount of cells with the increase of graphene content. All SMPU in this experiment were good biocompatibility of material and can be applied in the biomedical field.