丁二烯－八甲基环四硅氧烷的嵌段共聚合研究　Ⅰ．嵌段共聚物合成及D_4开环动力学

STUDIES ON THE BLOCK COPOLYMERIZATION OF BUTADIFNE AND OCTOMETHYLCYCLOTETRASILOXANE Ⅰ. SYNTHESIS OF THE BLOCK COPOLYMERS AND D_4 RINGOPENING KINETICS

以α－甲基萘钾为引发剂，按顺序加入丁二烯、八甲基环四硅氧烷（Ｄ４）在ＴＨＦ中进行负离子嵌段共聚，制备了聚了二烯－聚二甲基硅氧烷嵌段共聚物．讨论了聚合条件对嵌段共聚合过程的影响．考察了聚了二烯活性链引发Ｄ４进行嵌段共聚的反应动力学，求得在ＴＨＦ中３０℃时Ｄ４开环链增长的表观速率为１０ｋｇ／ｍｏｌ．ｈ、表观活化能为２８．３ｋＪ／ｍｏｌ．

Block copolymers of polybutadiene and polydimethylsi fo-cane, poly (Bdb--DMS), were prepared by sequential addition of butadiene and octomethylcyclotetrasi fo-cane(D.), using potassium α-methylnaphthalenide as initiator. Results show thatfinal conversion of D. varies significantly with its initial concentration, but not changewith the molecular weight and living chain end concentration of polybutadieneblocks; and also not with the polymerization temperature within 10-40oC. Studieswere also made on the ring-opening kinetics of D. during block copolymerizationinitiated by polybutadiene living chains. It is shown that the kinetic procedure issimilar to that initiated by small molecular anionic initiator. And the apparent rateconstant for D. propagation is found to be 10 kg/mol.h in THF at 30 ℃, and thecorresponding apparent activation energy to be 28.3 kJ/mol.