1,1-二苯基己基锂合成星形溶聚丁苯橡胶

Synthesis of star-shaped solution-polymerized styrene-butadiene rubber using 1,1-diphenylhexyllithium

以环己烷为溶剂,1,1-二苯基乙烯(DPE)与正丁基锂(n-BuLi)反应得到1,1-二苯基己基锂(DPHL),对其产率、稳定性和引发活性进行了研究。然后以DPHL为引发剂,四氢呋喃为结构调节剂,采用负离子聚合方法合成了线形溶聚丁苯橡胶(SSBR);最后以SnCl4偶联制备星形SSBR。用凝胶渗透色谱仪、核磁共振对产物进行了表征,考查了端基结构、聚合反应时间和偶联剂用量对SSBR偶联效率的影响,研究了硫化胶性能。结果表明,n(DPE)/n(n-BuLi)为1时,DPHL产率和纯度较佳,DPHL在2℃冰箱中保存时间超过30 d,浓度降为初始浓度的90%以下;引发剂残基"双苯环"存在于聚合物链末端;分子量为7×104,聚合反应时间为60 min,n(Cl-)/n(Li+)为1.12,偶联效率最高,端基转换为丁二烯后,偶联效率提高;与n-BuLi相比,由DPHL引发合成的星形SSBR的拉伸强度、撕裂强度和断裂伸长率有所提高,压缩疲劳温升降低,0℃时的tanδ更高,60℃时的tanδ更低。

1,1-diphenylhexyllithium（DPHL） was prepared by the addition reaction of n-butyllithium（n-BuLi） and 1,1-diphenylethlene（DPE）,with cyclohexane as solvent,and the factors affecting the yield,stability and initial activity of the product were studied.Linear-shaped solution-polymerized styrene-butadiene rubber（SSBR） was synthesized by ionic polymerization with DPHL as initiator,cyclohexane as solvent,and tetrahydrofuran（THF） as polar regulator.Star-shaped SSBR was subsequently prepared by a coupling reaction,using SnCl4 as the coupling agent.The coupling efficiency was measured.The effects of varying the structure of the chain ends,reaction time,and amount of SnCl4 on the coupling efficiency and the properties of the resulting SSBR were investigated.The results showed that the yield and purity of the DPHL were maximimized when n（DPE）/n（n-BuLi） was 1,the concentration decreased to below 90% of the original value if it was kept over 30 days at 2 ℃,and the diphenylalkyl group introduced by the initiator was present at the chain end of the polymers.The coupling efficiency was the highest when using the following reaction conditions： a molecular weight of 7.0 × 104,reaction time of 60 min,and n（Cl-）/n（Li＋） of 1.12;it could be increased further by converting the chain ends to butadiene.Compared with that obtained using n-BuLi as an initiator,the star-shaped SSBR initiated by DPHL possessed higher tensile strength,tear strength and elongation at break,lower compression temperature rise,higher tanδ at 0 ℃ and lower tanδ at 60 ℃.