The carbocationic polymerization of styrene(St) initiated by H2O/TiCl4 system was conducted at-60℃ in dichloromethane(CH2Cl2)/hexane(n-Hex)(50/50 V/V) in the presence of pyridine(Py),2-methyl pyridine(MPy...The carbocationic polymerization of styrene(St) initiated by H2O/TiCl4 system was conducted at-60℃ in dichloromethane(CH2Cl2)/hexane(n-Hex)(50/50 V/V) in the presence of pyridine(Py),2-methyl pyridine(MPy) and 2,6-dimethyl pyridine(DMPy).A desirable polymerization process with a relative slow polymerization rate and PS products with relatively narrow molecular weight distribution(MWD,Mw/Mn ca.1.8) were obtained.Py and its derivants and/or their complexes with Lewis acid TiCl4 interact with the growing chain end to reduced its 'cationicity' and thus to decrease the polymerization rate,suppress chain transfer and termination reactions and narrow MWD.The experimental results also show that the monomer conversion as well as the molecular weight of polymer products increased but MWD almost kept unchanged with polymerization time.The number-average molecular weight of polymer increased linearly with monomer conversion but the line did not pass through the origin.展开更多
以正己烷(n-Hex)为溶剂或n-Hex/一氯甲烷(CH3Cl)混合物为溶剂体系、氯化氢/氯化乙基铝/二氯二氰基苯醌为引发体系,采用正离子溶液聚合法对异丁烯(IB)与对甲基苯乙烯(p-Me St)在-90^-20℃下进行无规共聚,考察了n-Hex/CH3Cl(体积比)、二...以正己烷(n-Hex)为溶剂或n-Hex/一氯甲烷(CH3Cl)混合物为溶剂体系、氯化氢/氯化乙基铝/二氯二氰基苯醌为引发体系,采用正离子溶液聚合法对异丁烯(IB)与对甲基苯乙烯(p-Me St)在-90^-20℃下进行无规共聚,考察了n-Hex/CH3Cl(体积比)、二氯乙基铝(Et Al Cl2)/一氯二乙基铝(Et2Al Cl)(摩尔比)及反应温度对共聚反应转化率和共聚物相对分子质量的影响。结果表明,随着n-Hex/CH3Cl混合溶剂体系中n-Hex体积分数的增加,共聚反应转化率和共聚物的相对分子质量均下降;在Et Al Cl2/Et2Al Cl共引发体系中,随着Et2Al Cl摩尔比的增加,共聚物的相对分子质量不断增大;随着聚合反应温度的升高,共聚反应转化率和共聚物的相对分子质量均下降。展开更多
文摘The carbocationic polymerization of styrene(St) initiated by H2O/TiCl4 system was conducted at-60℃ in dichloromethane(CH2Cl2)/hexane(n-Hex)(50/50 V/V) in the presence of pyridine(Py),2-methyl pyridine(MPy) and 2,6-dimethyl pyridine(DMPy).A desirable polymerization process with a relative slow polymerization rate and PS products with relatively narrow molecular weight distribution(MWD,Mw/Mn ca.1.8) were obtained.Py and its derivants and/or their complexes with Lewis acid TiCl4 interact with the growing chain end to reduced its 'cationicity' and thus to decrease the polymerization rate,suppress chain transfer and termination reactions and narrow MWD.The experimental results also show that the monomer conversion as well as the molecular weight of polymer products increased but MWD almost kept unchanged with polymerization time.The number-average molecular weight of polymer increased linearly with monomer conversion but the line did not pass through the origin.
文摘以正己烷(n-Hex)为溶剂或n-Hex/一氯甲烷(CH3Cl)混合物为溶剂体系、氯化氢/氯化乙基铝/二氯二氰基苯醌为引发体系,采用正离子溶液聚合法对异丁烯(IB)与对甲基苯乙烯(p-Me St)在-90^-20℃下进行无规共聚,考察了n-Hex/CH3Cl(体积比)、二氯乙基铝(Et Al Cl2)/一氯二乙基铝(Et2Al Cl)(摩尔比)及反应温度对共聚反应转化率和共聚物相对分子质量的影响。结果表明,随着n-Hex/CH3Cl混合溶剂体系中n-Hex体积分数的增加,共聚反应转化率和共聚物的相对分子质量均下降;在Et Al Cl2/Et2Al Cl共引发体系中,随着Et2Al Cl摩尔比的增加,共聚物的相对分子质量不断增大;随着聚合反应温度的升高,共聚反应转化率和共聚物的相对分子质量均下降。