摘要
以四氢呋喃为极性添加剂,工业二乙烯基苯(DVB)为偶联剂,用阴离子聚合方法合成了星型聚丁二烯。用气相色谱法测定了聚丁二烯鋰与工业DVB四种单体(p-DVB,m-DVB,m-EVB,p-EVB)的偶联共聚速率,同时测定了反应活化能。结果表明:工业DVB四种单体的反应速率都比在纯环己烷中快,其中p-DVB和m-DVB的反应速率增加尤为明显;反应活化能分别为29.3,30.1,43.5和44.5kJ/mol,均比在纯环己烷中有大幅度地下降。改变THF/Li配比,p-DVB和m-DVB的反应速率随THF/Li增加而提高,而m-EVB和p-EVB的反应速率随THF/Li增加均出现极值。少量THF可加速偶联速率,当THF/Li=6时,在2～3分钟内可使偶联效率提高到90%。
By anionic polymerization star-type polybutadiene has been synthesized using commercial divinylbenzene as the coupling agent and tetrahydrofuran as the polar modifier. The reaction rates in the coupling copolymerization of polybutadiene lithium with four kinds of monomers in commercial divinylbenzenes (p-DVB, m-DVB, m-EVB and p-EVB) have heen determined by gas chromatography and their activation energy has also been measured. The experimental results show that the reaction rates of polybutadiene lithium with four kinds of monomers in the commercial divinyl benzenes are faster than the rates in the pure cyclohexane, and among them the increase of the reaction rate of p-DVB and m-DVB is particularly obvious. Addition of a little THF causes substantial decrease of the apparent activation energy of the four kiuds monomers in the commercial DVB (23.3, 30.1, 43.5, and 44.5 kJ/mol). As the ratio of THF/Li being changed, the reaction rate of the p-DVB and m-DVB increases with THF/Li, while the reaction rate of the m-EVB and p-EVB shows up an extreme value with the increase of THF/Li. Meanwhile a little of the THF can raise the rate of the coupling reaction and can raise the coupling efficiency to 90% within 2～3 minutes on the condition that the ratio of the THF/Li equals 6 and the temperature is 40℃.
关键词
星型聚丁二烯
THF
DVB
阴离子聚合
anionic polymerization
copolymerization
kinetics
gas chromatography
tetrahydrofuran
divinylbenzene
