Synthesis And Studies On Poly (Isobutylene-co-p-Methylstyrene) Random Copolymer

Cationic polymerization of isobutylene?IB?and p-methylstyrene?p-MeSt?in CH₃Cl solvent was conducted by using H₂O as initiator,ethylaluminium sesquichloride?Al₂Et₃Cl₃?as co-initiator.The structure of chain segment was researched and it was determined by gel permeation chromatography?GPC?and nuclear magnetic resonance spectra?¹H-NMR?,etc.In the experiment,we mainly studied the influence of reactive conditions and electron pair donors?EDs?on synthesis of poly?IB-co-p-MeSt?and also studied the polymerization of poly?IB-co-p-MeSt?in 4L polymerizer vessel.The study of the effect of reaction conditions on poly?IB-co-p-MeSt?showed that the lower polymerization temperature was,the higher relative molecular weight could obtain.So because of the limitation of reaction conditions,the polymerization temperature should be set at-85 ^oC^-95^oC and the optimum reaction temperature was 300s.At the same time,we researched the influence of electron pair donors?EDs?on the synthesis of poly?IB-co-p-MeSt?,and the results showed that:?1?the complex of initiator with electron pair donors was conducive to reacting with polymerizable monomers;?2?when the electron donor concentration was higher than a certain value,monomer conversion began to decrease markedly.Therefore,these conversions had an optimal concentration for electron donors and the optimal concentrations of ethyl acetate,DMF,and acetone were 0.45,0.35,and 0.45 mmol·L^-1,respectively.In addition,the change of temperature during polymerization process was researched and showed the exothermic quantity was decreased with the increasing of EDs;?3?Under the condition of invariable yield,molecule weight and molecule weight,the reaction temperature was able to be elevated;?4?Addition of 0.45mmol·L-1 ethyl acetate resulted in the content of p-MeSt was much closer to the monomer feed ratio than that of polymers carried out without ED.The RI and UV traces of the IB/p-MS random copolymers obtained in ethyl acetate were close to perfect overlapping.In the study of the polymerization of poly?IB-co-p-MeSt?in 4L polymerizer vessel,we were able to control the operating system of the polymerization;The yield of the poly?IB-co-p-MeSt?increased with increasing concentration of Al,decreased vigorously when the molecular weight was larger than a certain value.Considering the the effect of Al on the polymerization system,concentration of Al should be at 5×10^-3mol·L^-1.The observation confirmed that ethyl acetate was effective for controlling the polymerization rate and slowing down the exothermic quantity.