Preparation Of Bio-based Biodegradable Polyurethanes And The Regulation Of Their Structures And Properties

Biodegradable polymers refer to those polymers that can substitute the structures or functions of some body tissues or organs in a safe.reliable,economical and biocompatible way.and the degradation products of which are nontoxic to human body.Biodegradable polymers can be obtained from nature,microbiological synthesis and chemical synthesis.Chemically synthesized polymers have adjustable structures and excellent performance,and therefore have high value in research and multiple application fields.Polyurethanes(PUs)are polymers that have NHCOO groups in their backbones.PUs are considered as a valuable medical material because they have excellent mechanical strength and bending resistance,and have high degree of freedom in the design of their molecular structure.However,traditional PUs cannot be naturally degraded.The synthesis of biodegradable PUs are mainly through the introduction of biodegradable components into the chains of PUs.The performance of PUs can be tuned by changing the structures and ratios of the hard and soft segments.In this work,three different types of novel bio-based PUs were synthesis by choosing three different types of raw material:natural-based castor oil,polyhydroxybutyrate valerate(PHBV)and polyvinyl alcohol(PVA).The synthesis method and the relationship between the molecular structure of these PUs are studied,and their biomedical application are discussed.Bio-based PU flexible foams were synthesized by introducing castor oil,polyethylene glycol(PEG)and diphenyl methane diisocyanate(MDI)using the prepolymer method.The influence of the castor oil component in the prepolymers on the microstructure,the water uptake property,and hydrophilic performance of the castor oil-based PU flexible foams were systematically investigated.With the increasing content of castor oil,the content of hydrogen bonds and NHCOO groups decreases,the crosslinking density increases,and the porosity decreases.The microstructure and bore diameter also change.Different antibacterial agents such as polylysine,chitosan and nano Ag particles were incorporated into the PU foam,and the antibacterial properties were compared.Then novel PIIBV-based PU was synthesized using PHBV-diol.PEG and MDI via the prepolymer method,and a series of PHBV PU films was obtained by changing the content of PHBV.With the increase of PHBV content,the degree of microphase separation increased the mechanical strength obviously increased.and the degradability also increased.The introduction of PEG improves the hydrophilicity of PUs.We verified that,PUs with microphase separation have excellent anticoagulant property and are beneficial to the adhesion and proliferation of cells.PHBV PUs have potential medical applications in anticoagulant materials.Nanoscale waterborne polyurethane solution was prepared,and PVA-based PU hydrogels were synthesized by cross-linking waterborne polyurethane(WPU)solution with PVA solution for the first time,using the freezing-thawing physical cross-linking method.The strucuture and morphology of the PU composite hydrogel were characterized by means of FTIR,SEM and TGA.With the increasing content of WPU,the number of pores on the surface of the material increasesd.and the thermos ability,water absorbing capacity,and mechanical property improved.The proliferation of MSC and cytotoxicity tests showed that the PVA-based PU hydrogels have good cytocompatibility.In conclusion,the CO-based PU foams,the PHBV-based PU thin films and the PVA-based PU hydrogels synthesized in this paper are derived from green materials and have good biocompatibility.Therefore,they laid the theoretical and experimental foundation for the application of novel bio-based PUs in the medical field.