Study On The Terminal Allylation And Silylation Technique Of Polyether

The alkoxylation reaction, terminal allylation reaction and the purification technics of crude allyl-terminated polyether were studied as the polyether polyol with double hydroxyl and polyether with one hydroxyl and one unsaturated link were raw material. Especially the kinetic and reaction mechanism of allylation reaction were discussed and the rate equation was drawn. Simultaneously, the structure and performance of the allyl-terminated polyether was characterized and the hydrosilylation reaction of the allyl-terminated polyether was discussed briefly. Firstly the technics of polyether alkoxylation was studied. The activation of three alkoxylation reagents including NaOMe, sodium and KOH was investigated which indicated that NaOMe was the best alkoxylation reagent. The influence of reaction time, reaction temperature, molecular weight of polyether and the dosage of alkoxylation reagent on the alkoxide introduction rate was studied and the optimum condition was determined by experimentation. The terminal allylation reaction was studied which was influenced by reaction time, reaction temperature, category and dosage of allylation reagent and molecular weight of polyether. After allyl-terminated polyether with high introduction rate was prepared, the structure and performace of product was tested and characterized by menas of instruments. The activation energy and rate constant of the allylation reaction was calculated in virtue of kinetic study. The kinetics study indicated that the allylation reaction of polyether was second order and its reaction mechanism was SN2 nucleophilic substitution. The polyether with one hydroxyl and one unsaturated link which was initiated from allyl alcohol also was used to prepare unsaturated link-terminated polyether by doubling chain reaction, but the product was not appropriate for sealants because of its broad molecular weight distribution. The purification of crude allyl-terminated polyether was studied which was carried by modified neutralization-absorption method. The influence of the dosage of neutralization reagent and absorption reagent on the filtration rate, product acid number and color was studied and the optimum purification technique was drawn. The slyl-terminated polyether was prepared from allyl-terminated polyether and DMS by way of hydrosilylation reaction. As the catalyst of the reaction, chloroplatic acid was dissolved in tetrahydrofuran and isoropanol. After the reaction was carried out at 90℃for 3 hours, the silyl-terminated polyether with silyl introduction rate of 78% was obtained. Moreover, the H1NMR spectra indicated that the silyl-terminated polyether with a little remnants terminal allyl prepared in this paper was better than the sample of Kaneka Corporation.