STUDIES ON AMINOSILANE COMPOUNDS AS EXTERNAL ELECTRON DONORS IN 1-BUTENE POLYMERIZATION

Abstract

Four aminosilane compounds as external electron donors were synthesized and employed for 1-butene polymerization with MgCl2 supported Ziegler-Natta catalyst.The four aminosilane compounds are di(piperidinyl)dimethoxysilane(DPPDMS),di(piperidinyl)diethoxysilane(DPPDES),di(pyrrolidinyl)-dimethoxysilane(DPRDMS) and di(pyrrolidinyl)diethoxysilane(DPRDES).The effects of the structure of different external donors on the catalytic efficiency,isotacticity,melting temperature and molecular weight distribution of resulted poly(1-butene) were investigated in detail.Poly(1-butene)s have been characterized by using gel permeation chromatography(GPC) and differential scanning calorimetry(DSC) analysis.The results indicated that the aminosilane compounds possessing dimethoxy groups showed higher catalytic efficiency and isospecificity of polymers than those of compounds having diethoxy groups,whereas the aminosilane compounds containing diethoxy groups were benefit for obtaining broader molecular weight distribution polymers than those of compounds possessing dimethoxy groups.Furthermore,compared with DPPDMS or TEOS as external donor,DPPDMS/TEOS compound as complex external donor at a proper molar ratio not only increased the catalytic efficiency and isotacticity of polymers obtained,but also broadened the molecular weight distribution of the polymer.Moreover,the effects of different amount of hydrogen and concentration of external donor and cocatalyst on catalytic efficiency and isotacticity of polymers obtained were also studied.