Simple Polymerization And Application Of Biodegradable Polymers

Polymer materials are the fastest developing materials since the 21 st century,but with the use of a large number of polymer materials,they also cause huge pollution to the environment.The polymer structure of polyolefin and other materials is stable and difficult to degrade,which brings great problems to recycling and treatment.Polycarbonate,polyester and functional materials based on polyester or polycarbonate have degradation function and can be rapidly degraded in the natural environment after being discarded,which provides an important way to solve environmental pollution.At present,the existing synthetic methods of biodegradable polymers are single and have some shortcomings,so it is of certain social value and practical significance to study some novel synthetic methods of biodegradable polymers.(1)In this experiment,the high molecular weight polycarbonate was prepared by two-step method using the transesterification reaction of binary carbonate with diol,diamine and polyol catalyzed by phosphononitrile organic base with good solubility and adjustable base.On the one hand,the use of phosphononitrile organic base catalyst greatly improves the reaction efficiency,reduces the reaction temperature,improves the molecular weight of the polymer,and avoids the residual problem of traditional metal catalyst in the polymer.The products were characterized by differential scanning calorimeter,thermogravimetric analyzer,nuclear magnetic resonance spectrometer,electronic universal test stretcher,rheometer and other instruments.The molecular weight of aliphatic polycarbonate prepared by this method is up to 264.02 kg/mol,the highest melting point of the product is78℃,and the thermal decomposition temperature of 5% is up to 360℃.The tensile strength of the film prepared by the polymer is 13.39 MPa,and the elongation at break is up to 810%,which is similar to the performance of the daily use of PE film and has excellent degradation performance.In addition,polymers with different properties can be made by adjusting the monomer structure to meet different application scenarios.According to this method,polycarbonate with high molecular weight can be obtained simply and conveniently.The reaction conditions are mild and the cost is low.It is very suitable for industrial production and can effectively solve the environmental problems caused by the overuse of polymer film materials.(2)In this experiment,hydroxyethyl acrylate(HEA)was used to proton transfer polymerization direct synthesis of high molecular weight polyester ether under the catalysis of organic base.This method avoids the disadvantage of the traditional A-A and B-B polycondensation reaction in which the molar ratio of groups is easily unbalanced,resulting in the inability to form polymers with high molecular weight.However,in the process of research,we found that under the catalysis of organic bases,HEA can not only carry out the oxygen Michael addition,but also the carbon Michael addition side reaction.The overhanging double bond formed by the addition of carbon Michael is an imbalance of the ratio of hydroxyl to acrylic double bond,which prevents the formation of high molecular weight polymers.Therefore,in view of the abnormal consumption of double bonds in the polymerization system,quantitative diene monomers were added at the later stage of polymerization to regulate the ratio of hydroxyl and acrylic double bonds in the polymerization system,so as to achieve a higher conversion rate and obtain polymers with high molecular weight.From the experimental results,our method is very effective,we finally got a number of molecular weight up to 355.93 kg/mol of polyester ether.Then we by introducing a second monomer acrylamide(Am)to adjust the mechanical properties of polymer,and through the uv-curable microfluidic spinning preparation PHEA-Am surgical suture.The tensile strength of the he PHEA-Am surgical suture can reach 28.87 MPa,at the same time has good cell compatibility and efficient endocytosis and degrade.In addition,this synthetic method is simple,and the price of raw materials is lower than that of existing artificial surgical sutures.Therefore,surgical sutures synthesized by this method have a certain application prospect.(3)Conventional epoxy resin thermosets have been widely used for their good mechanical and thermal properties,but they are burdensome to be recycled,reprocessed,and reshaped in virtue of their permanent covalent crosslinks.Here,we synthesized a novel epoxy vitrimer from abundant and renewable epoxy soybean oil(ESO)without catalyst and solvent and produced epoxy vitrimer combining excellent reprocessing,trigger-degradable properties.And then we used the self-healing ability of vitrimer to prepare a generative bilayer vitrimer with different properties on both sides,which can undergo a series of programmed shape transitions via the storage and release of internal stresses.Based on the controllable deformation and excellent recovery properties,this work designed a series of soft actuators capable to finish more complex actions under program control.Our work provides a green strategy and design space for epoxy-vitrimer and paves way for the design and development of bioinspired soft matter for a broad range of applications in intelligent materials.