Based On The Synthesis Of Aliphatic Polycarbonates And Their Cross-linking Modification

Due to its favorable biodegradability,biocompatibility,non-toxicity and resistance to hydrolysis,aliphatic polycarbonates have been applied in the field such as medical materials,waterborne polyurethane and environmental protection.At present,the traditional synthese of aliphatic polycarbonates do harm to the environment,and the consumption of raw materials is high.In particular,the poor thermal and mechanical properties of aliphatic polycarbonates will limit its mass productions and applications.In this thesis,in order to improve the heat-resistance and mechanical properties of aliphatic polycarbonates,using dimethyl carbonate(DMC)and aliphatic diols as raw materials,aliphatic polycarbonates were synthesized by two-step transesterification.In this way,the process was simple and environmental-friendly.The obtained polymers had lighter color,narrower distribution of molecular weight and lower residue of small molecules.Then,the crosslinking modification was carried out by direct and indirect methods.Characterized by TG,the indirect method was better than the direct method in improving heat-resistance of aliphatic polycarbonates.The initial decomposition temperature was increased by about 25?40 ?,and the final decomposition temperature was increased by about 45?60 ?.It is crucial that modified aliphatic polycarbonate exhibited the perfect swelling properties,which could be used in the leakage of oil and organic contamination.It can adsorb the solvent to a size that is several even hundred times bigger than itself,and the adsorption capacity can reach more than 2000%.In general,two methods were used to synthesize crosslinked polycarbonates,and the effects of different solvents,monomers,dosages of crosslinker,atmospheric temperature on the adsorption properties of crosslinked polycarbonates were studied.Moreover,the reusability,absorption capacity of oil spill,adsorption and desorption kinetics were also studied.The structures and properties of the polymers were characterized by FT,IR,PXRD and TG,which laid a profound theoretical basis for the practical application of adsorbents.