Preparation And Properties Of Pyridine Betaine Zwitterionic Shape Memory Polyurethane

Shape memory polyurethanes(SMPUs)as new intelligent materials,has received increasing attention due to their excellent proprerties such as a broad adjustable transition temperature and controllable structural performance.However,traditional SMPUs have single shape performance,which triggered inflammation after applying to the body after a long time,it is necessary to modify the structure and peroperties of SMPUs.On the other hand,zwitterionic polymers have super hydrophilic anionic groups and cationic groups,which can form strong ionic hydration layers to provide good biocompatibility and resistance to biological contamination.Further study should be paid more attention on smart application.In this study,to design and prepare zwitterionic SMPUs,which have thermal shape memory,wet sensitive response memory and biocompatibility in combination with the structural characteristics and functional properties of SMPUs and zwitterionic polymers.Firstly,pyridine type zwitterionic shape memory polyurethane(PEGZPUs)which was made up of polyethylene glycol(PEG4000)as the soft segment and BINAPS-HDI as the hard segment,was synthesized by the reaction of PEG4000,hexamethylene diisocyanate(HDI),N,N-dihydroxyethyl isonicotine(BINA),and 1,3-propane sulfonic acid(1,3-PS).The structure and properties of PEGZPUs were systematically characterized and studied.The results showed that PEG4000 had a good crystallinity at room temperature.With increasing the content of BINAPS,the crystal form of PEG4000 will be gradually increased,and the tensile strength of PEGZPUs will be gradually improved.PEGZPUs have bending shape memory performance,but the overall tensile strength of PEGZPUs still can not meet the practical application.Secondly,pyridine type zwitterionic shape memory polyurethane(PyZPUs)which was made up of BINA-HDI as the soft segment and MDI-BDO as the hard segment(35% hardness content),was synthesized by the reaction of BINA,HDI,diphenylmethane-4,4-diisocyanate(L-MDI),1,4-butanediol(BDO),and 1,3-PS to.Their structures and properties were systematically studied.The results showed that the thermal stability and thermomechanical properties of PyZPUs were improved with increasing the content of BINAPS,and the shape recovery rate of PyZPUs was significantly improved after adding the moderate content of BINAPS.PyZPUs have good multi-shape memory performance,cyclic shape memory performance,and wet-sensitive shape memory performance.In addition,the biocompatibility of PyZPUs was also tested and it was concluded that the moderate content of BINAPS play a better effection on the biocompatibility of PyZPUs.Finally,in order to improve the tensile strength of SMPUs,polyurethanes with cross-linked structure were synthesized.The prepolymer was synthesized by reaction of BINA and HDI,and then pentaerythritol was used as cross-linker to prepare a cross-linker structural SMPUs.After reaction with 1,3-PS,the zygotic ion-shaped memory polyurethane CZPUs were synthesized,and its structure and performance were also systematically studied.The results showed that the shape recovery rate of CZPUs firstly decreased and then increased,and the final recovery rate of CZPU10 was higher than that of CZPU0.In addition,CZPUs also have good dual and multi-shape memory performance,cyclic shape memory performance and wet-sensitive shape memory performance.