Preparation, Characterization And Performance Studies Of Biocompatible Wet-sensitive Zwitterionic Shape Memory Polymers

Shape memory polymers(SMPs) and Zwitterionic polymers both have great applications in biomedical fields. However, most of the biological compatibility of SMPs at not ideal at present, their applications on biological applications have been limited. Zwitterionic polymers can form strong ionic hydration layers due to the super hydrophilic anionic and cationic groups, thus Zwitterionic polymers show good biological compatibility, blood compatibility and anti biofouling etc.. Therefore, this work innovatively combines functionalities of zwitterionic polymers and SMPs, systematically studies a series of ZSMPs with shape memory properties and biocompatibility.Firstly, a series of PEG based shape memory polyurethanes(PEGSMPU) with various hard segment contents are synthesized successfully by bulk polymerization method from liquefied 4,4'-diphenylmethane diisocyanate(L-MDI), 1, 4-butanediol(BDO) and Polyethylene glycol(PEG). The structure and properties of PEGSMPUs are investigated systematically. The results demonstrated that only PEGSMPUs containing less than 40 wt% hard segment content(HSC) have low cytotoxicity. It is thus conclued tha PEGSMPUs bearing both good shape memory effects and good biocomatibility when the HSC is less than 35 wt%.Secondly, this project had synthesized one kind of zwitterionic shape memory polyurethane(ZSMPU) through the reaction of glycol containing tertinary amine(like MDEA) with diisocyanates(like HDI), followed by betainization reaction with 1,3-propane sultone(1,3-PS). The structure and properties of ZSMPUs are investigated systematically. The results show that this SMPU system has good hydrophilic properties. Zwitterionic structure affacts the glass transition temperature(Tg) greatly. ZSMPUs show micro-phase separation structure and multiple shape memory effect. The shape recovery also decreases with the increase of zwitterionic structure content. In addition, we also found that ZSMPUs have special self-repairing properties by immersing in humidity or water condition, after drying at low temperature. The research for cell viability demonstrate that ZSMPUs also have good biocompatibility. The higher zwitterionic structure conten, the less biological toxicity.Finally, this project had also synthesized another kind of DMAPS-co-AA copolymer(p(DMAPS-co-AA)) for zwitterionic SMP by selecting functional zwitterionic monomer(DMAPS), with other functional monomer(AA), using emulsion method. The structure and properties of DMAPS-co-AA are investigated systematically. The results demonstrate that the DMAPS-co-AA can show multiple-shape memory effect, including triple-shape memory effect and dual-shape memory effect. all copolymers show good shape fixity while the shape recovery decreases with the increasing of zwitterionic structure content. Additionally, this kind of SMP also shows good biocompatibility. The higher DMAPS content, the less biological toxicity. Moreover, the DMAPS-co-AA copolymer can stimulate the phagocytosis of macrophage(RAW264.7). The higher DMAPS content, the better phagocytic activity of bacteria. Therefore, the DMAPS-co-AA copolymer can be used to control the macrophage for phagocytosis of the invasion cells. In a word, through the systematic studies on these two systems of zwitterionic shape memory polymer(ZSMP), the project successfully found that the ZSMPs have good biocompatibility and good multiple shape memory effect. There is also the opportunity to achieve self-repairing properties and antibacterial properties in ZSMPs. Therefore, they can be used as an intelligent biomedical polymeric material in biomedical field, showing good economic value and important social benefits.