Study On Preparation And Properties Of Polycarbonate Urethane/Nano-ZnO Biomedical Composite

The incidence of cardiovascular and cerebrovascular diseases has also increased year by year,and it has become the number one cause of death around the world with the economic development and the aging population in recent years.Polycarbonate urethane(PCU)has been widely used in biomedical field because of the suitable biodegradation rate,good hydrolysis resistance and oxidation resistance,and excellent mechanical properties,etc.In order to develop PCU thermoplastic elastomer material with anticoagulant properties.In this paper,a series of multi-block PCU elastomers and PCU/Zn O composite materials were designed and synthesized.The effects of the hard segment contents,the diverse types and contents of diisocyanate,and the nano-zinc oxide contents on the microphase structure and various properties of PCU were investigated.The main research contents and conclusions are as follows:(1)Polyhexamethylene carbonate diol(PHMC diol-2000)with a relative molecular mass of 2000 was used as the soft segment.Isophorone diisocyanate(IPDI)and the chain extender 1,4-butanediol(BDO)were used as the hard segment.Dibutyltin dilaurate(DBDTL)was the catalyst and dimethyl carbonate(DMC)was the solvent.Polycarbonate urethane(PCU)were synthesized by the prepolymerization method.The structure and properties of PCU thermoplastic elastomers were analyzed via infrared spectroscopy(IR),nuclear magnetic resonance hydrogen spectroscopy(~1H-NMR),gel permeation chromatography(GPC),X-ray diffraction(XRD),differential scanning calorimetry(DSC),thermogravimetric analysis(TGA),tensile test and so on.The effects of hard segment contents on the crystalline performance,thermal stability and tensile property of PCU were explored.XRD and DSC demonstrated that it has certain crystallinity when the hard segment content is less than30%,and the melting point T_m gradually rises with the increase of the hard segment content.TGA illustrated that the decomposition temperature is raise from 334.9℃to352.3℃with the decrease of the hard segment content,and thermal stability is increased.The tensile test revealed that the samples all have yield phenomenon when the hard segment content is less than 30%,of which the PCU with a hard segment content of 15%has the highest tensile strength(42.0 MPa)and the elongation at break(1167%).(2)Based on the previous research work(1),PHMC diol-2000 was used as the soft segment,and hexamethylene diisocyanate(HDI)was introduced to form the hard segment with IPDI and BDO.PCU with the diverse ratios of the amount of substances of HDI and IPDI were synthesized by prepolymerizaion method.The effects of different types and contents of diisocyanate on the properties of PCU were investigated.XRD and DSC indicated that when a low content of HDI is introduced,PCU has the strongest crystallization ability,and the melting point T_m gradually drops with the rise of HDI content.TGA demonstrated that with the increase of HDI content,the decomposition temperature gradually raises and the thermal stability improves.HDI is benefit to promote the micro-phase separation between the hard and soft segments.The tensile test revealed that PCU with a low HDI content has a certain yield strength,the tensile strength is 36.0 MPa,the elongation at break is 744%and the elastic modulus is 15.7 MPa.The comprehensive performance is optimal.(3)Based on the previous research work(1),PHMC-diol 2000 is used as the soft segment,IPDI and BDO were used as the hard segment.PCU/Zn O composites with diverse nano-Zn O contents were prepared by in-situ prepolymerization method.The effects of diverse contents nano-Zn O on the properties of PCU were discussed.TGA demonstrated that the degree of microphase separation between the hard and soft segments intensifies when the content of nano-Zn O is 10-20%.The decomposition temperature rises and the thermal stability promotes with the decreases of the nano-Zn O content.The tensile test illustrated that compared with PCU without nano-Zn O,the tensile strength(from 36.1 MPa to 47.4 MPa)and the elastic modulus(from 17.9MPa to 114.6 MPa)of PCU/Zn O-5%have significantly improved.