Study On Acetoacetate Modified Bio-based Knoevenagel Curing System

With the increasingly severe environmental problems and the reduction of petrochemical products,the use of renewable resources as raw materials instead of petrochemical raw materials to prepare polymers has gradually attracted people’s attention.In this article,we will use sucrose,epoxy soybean oil and other bio-based raw materials to modify bio-based raw materials through transesterification,epoxy ring-opening and other reactions to prepare acetoacetate modified bio-based resin and condense by Knoevenagel The reaction prepares a cured coating at room temperature,and studies the mechanical properties,thermal stability,swelling rate and cross-link density of the coating.The main contents are as follows:1.Study on Knoevenagel cross-linking curing system of acetoacetate esterified sucrose and aromatic diformaldehydeAcetoacetate esterified sucrose was synthesized by transesterification using sucrose and tert-butyl acetoacetate as raw materials.The rheometer was used to measure the gel time of the cross-linked system to predict the possible reaction mechanism,and the best choice was made by the gel time Coating preparation process.The gel point determination experiment shows that:first react hexahydropyridine(catalyst)with 4,4-biphenyldicarbaldehyde,then add acetoacetate to sucrose to obtain the shortest gel time,and then prepare the coating by this process The study found that the coating has a pencil hardness of 6H and a gel content of 96%.It has high mechanical properties,high glass transition temperature,and good thermal stability.2.Study on Knoevenagel cross-linking curing system of acetoacetate esterified soybean oil and aromatic diformaldehydeUse epoxy soybean oil,methanol,water and boron tetrafluoride to synthesize soybean oil-based polyol through epoxy ring-opening reaction,and then transesterify soybean oil-based polyol with tert-butyl acetoacetate to obtain acetoacetate esterification.Soybean oil.Nuclear magnetic resonance hydrogen spectroscopy,carbon spectroscopy,infrared spectroscopy and other characterization methods prove that the synthesized product is the target product acetoacetated soybean oil,and the synthesized acetoacetated soybean oil is reacted with the cross-linking agent phthalaldehyde,The Knoevenagel reaction was carried out using hexahydropyridine,1,8-diazabicycloundec-7-ene(DBU),4-dimethylaminopyridine(DMAP)and triethylamine as catalysts.The test results show that the polymer has good thermal stability,T_g up to 52~oC,Young’s modulus up to 24.91MPa,tensile strength up to5.65MPa,elongation at break up to 286%.