Ring-Opening Polymerization With Organic Metal-Free Alkaline Catalyst

At present,metal and organometallic compounds occupy a major position in the field of polymerization catalysis,but the existence of residual metal components will be the problem.Therefore,organic metal-free catalysts are needed.Strong alkaline organic catalysts have good catalytic activity and can effectively improve the rate of polymerization without metal ions.This thesis mainly studies the homopolymerization and copolymerization reaction with organic metal-free alkaline catalyst.The main organic metal-free catalysts used in the study are phosphazene?t-Bu P₄?,1,8-diazacyclo-[5,4,0]undec-7-ene?DBU?and 1,5,7-Triazabicyclo[4.4.0]dec-5-ene?TBD?.Through the catalysis of the above catalyst,the anionic active center was formed.1,5-dioxepan-2-one?DXO?were polymerized by open ring polymerization,and the copolymerization of ethylene oxide?EO?and tert-butyl methacrylate?TBMA?was also catalyzed.The related reaction kinetics and possible reaction mechanism were also explored.The application of copolymer of ethylene oxide?EO?and tert butyl methacrylate?TBMA?was preliminarily explored.The main results are as follows:The polymerization of DXO was catalyzed by organic metal-free catalysts t-Bu P₄,DBU and TBD,respectively.It was found that the three can catalyze the polymerization of DXO.The product with narrow polydispersity index was obtained.The kinetic experiments proved that polymerization was controlled/living.It took only 8 minutes to polymerize with t-Bu P₄ as catalyst at 25oC when the molar ratio of the monomer to the initiator was 100,but TBD and DBU needed 50min and 3h respectively.t-Bu P₄ was the fastest.In view of the gel phenomenon occurring at 60oC experiment,we have made an explanation through the characterization of NMR.t-Bu P₄ was used as a catalyst to catalyze the copolymerization of ethylene oxide?EO?and tert butyl methacrylate?TBMA?.Because the molecular weight distribution of the polymers was very wide,the samples were classified by sedimentation,and the fractions with narrow distribution were obtained,the products and their fractions were characterized by NMR,differential scanning calorimetry,gel permeation chromatography and infrared spectroscopy.The results showed that the polymers obtained were indeed copolymers.At the same time,we found the existence of transesterification in polymerization,which is also one of the factors that broaden the molecular weight distribution.Finally,the application of copolymers in electrolytes was also studied,the ion conductivity can reach 2.23?10^-66 S/cm even after doped with large amount of adhesives,which is an order of magnitude higher than that of pure PEO.