Synthesis And Properties Of The End-functionalized Poly(Trimethylene Carbonate)and Copolymers

Aliphatic polycarbonates are a kind of biodegradable materials with excellent properties,which do not produce acidic products during degradation and have good biocompatibility,and can be used in biomedical fields widely,such as surgical sutures,drug controlled release,tissue engineering,etc.As known,diosgenin is a natural compound that is extracted from Dioscorea zingiberensis(also known as turmeric),and it is a main raw material for the synthesis of sex hormones,steroids and other steroid compounds.Due to its multiple biological activities,it has the functions of inhibiting the proliferation of some cancer cells,anti-thrombosis,enhancing the immune activity of regulatory T cell,and fighting infection,In addition,the diosgenin and its derivatives have good biocompatibility,which can be introduced into a specific structure as a biologically active liquid crystal functional motif.At present,there are no reports on the introduction of diosgenin derivatives bio-liquid crystal units into the aliphatic polycarbonate backbone.The design idea of this paper is to introduce the diosgenin derivative into the terminal group of poly(trimethylene carbonate)(PTMC),to design end functionalized aliphatic polycarbonate polymers,The liquid crystal properties and drug-loading behavior of carbonates have laid a solid foundation for further exploration of its application in medicine.In Chapter 2,firstly used the chain extension reaction to prepare the liquid crystalline intermediate 6-dioxin saponin oxyhexanol[Dios-(CH2)6-OH]containing diosgenin.Then Dios-(CH2)6-OH was used as the reactant,and the hydroxyl group of Dios-(CH2)6-OH was used to initiate the ring-opening polymerization of trimethylene carbonate(TMC).Three kinds of terminal groups were obtained.The saponified polytrimethylene carbonate Dios-(CH2)6-(TMC)n was used to characterize its structure and related properties by means of FT-IR,1H NMR,DSC and POM.The results show that the three kinds of homopolymers Dios-(CH2)6-(TMC)n are in the liquid crystal state at room temperature.The POM observation shows that the fan-shaped texture;the isotropic point of the polymer increases with the increase of the liquid crystal element content;the TG results showed that the thermal decomposition temperatures of the three polymers were all above 220?.In Chapter 3,the ring-opening copolymerization of(TMC)and d,1-lactone(DLLA)was initiated with the hydroxyl group of Dios-(CH2)6-OH.To investigate the effect of monomer molar ratio on liquid crystal behavior,three copolymers of Dios-(CH2)6-(TMC)x-(DLLA)y with different composition were prepared,in which the molar ratio of Dios-(CH2)6-OH to the monomers was given at 1:4,and the moalr ratios of TMC to DLLA was variable.In another experiment,to investigate the influnce of the Dios-(CH2)6-OH amount on the polymer's liquid crystal behavior,three copolymers were also prepared,in which the moalr ratio of TMC to DLLA was given at 1:1,while the moalr ratio of Dios-(CH2)6-OH to the monomers was variable.The structure and properties of all the prepared polymers were characterized by FT-IR,1H NMR,POM and DSC.The results showed that with the increase of DLLA content,the isotropic point of the copolymer decreased,while the thermal stability increased.Furthermore,with the increase of diosgenin derivatives content,the liquid crystallinity have increased,the thermal stability have increased.In Chapter 4,end group functionalized polytrimethylene carbonate microspheres were prepared by auxiliary precipitation method.The results show that terminally functionalized polytrimethylene carbonate Dios-(CH2)6-(TMC)n-1 can achieve self-assembly drug loading and form spherical micelles,the follow-up study will deepen the exploration of drug delivery behavior.