Study On The Dynamic Covalent Bond Of Borate Ester Enhancing The Mechanical Properties Of Epoxy Oil Polymer

In the 21^stcentury,the contradiction between the rapid development of science and technology,the shortage of fossil resources and environmental pollution is gradually alleviating with the development and utilization of replaceable,environmental friendly and renewable resources.Biomass resources are widely used in industrial production and scientific research because of their renewablility,low pollution and distribution,to realize the great pursuit of"Lucid waters and lush mountains are invaluable assets".In general,the prepared polymer needs to be synthesized by further crosslinking to form useful materials.Normally,the following three crosslinking methods are used:chemical,optical and irradiation crosslinking.In this thesis,the vegetable oil-based epoxy polymer was prepared by free radical polymerization.And then,the polymers were toughened by dynamic covalent bond of boric acid ester,endowing the materials with excellent mechanical properties and recycle utilization.The content of this thesis is divided into three aspects:1.Two kinds of monomers（KOE and KOEO）were synthesized by using sunflower seed oil with high oleic acid content as raw material.Finally,AIBN was used as initiator to copolymerize the two monomers to obtain the epoxy oil polymer（KOEEOP）.Gel permeation chromatography showed that the molecular weight of epoxy resin was about 50k D,and the NMR spectrum showed that the conversion rate was 95%.2.The epoxy polymer of sunflower seed oil possesses poor mechanical properties.The epoxy oil polymer was reinforced and toughened by dynamic reversible crosslinking,reversible borate ester dynamic covalent bond which was formed between phenylboronic acid and diols to crosslink the pant-oil based polymer.Compared with the traditional irreversible permanent crosslinking method,the polymer materials crosslinked by dynamic covalent bond have reprocessing properties,and the mechanical properties of the polymer can be protected by the dynamic covalent bond reassociation;3.Prepared three kinds of phenylboronic acid crosslinking agents and compared their toughening ability.The tensile strength study showed that the crosslinking method of small molecule was more effective in toughening epoxy oil polymer,and it had higher mechanical properties than the same type of borate crosslinking agent.The results show that the toughening ability of three kinds of crosslinking agents of nano particle,small molecule and large molecule is in the order of nanoparticle crosslinking agent>small molecule crosslinking agent>large molecule crosslinking agent.The maximum tensile stress of the material toughened by nano particle can reach 12 MPa,and the second compression tensile test can reach 20 MPa after recovery.