新癸酸钕/烷基铝/二异丁基氯化铝催化丁二烯/异戊二烯共聚合

Copolymerization of butadiene/isoprene catalyzed by neodymium neodecanoate/alkylaluminum/di-i-butylaluminum chloride

采用新癸酸钕(简称Nd)/烷基铝[Al(i-Bu)2H或Al(i-Bu)3(简称Al)]/二异丁基氯化铝(简称Cl)催化剂对丁二烯(Bd)/异戊二烯(Ip)进行共聚合,考察了Al种类及单体配比对Bd/Ip共聚合的影响,通过凝胶渗透色谱(GPC)、傅里叶变换红外光谱和核磁共振氢谱表征了共聚物,研究了2种催化剂体系聚合过程中单体的竞聚率及所得共聚物的序列分布。结果表明,2种催化剂体系所得共聚物中聚丁二烯(PB)和聚异戊二烯(PI)链节的顺式-1,4-结构摩尔分数均超过97%,且Al(i-Bu)2H催化体系的活性明显高于Al(i-Bu)3催化体系,但前者所得共聚物的数均分子量相对较低,分子量分布较宽,GPC曲线呈双峰,而后者所得共聚物的GPC曲线呈单峰;随着单体Bd用量的增加,2种催化剂体系所得共聚物中PB链节的顺式-1,4-结构摩尔分数均超过99%,而PI链节的顺式-1,4-结构摩尔分数则随着单体Ip用量的增加而略有降低,且Al(i-Bu)3催化体系所得共聚物中2种链节的摩尔分数与单体用量基本一致,而Al(i-Bu)2H催化体系所得共聚物中PB链节含量略高于单体Bd用量;在2种催化体系中,Bd易于自身均聚,Ip更容易与Bd共聚合,以Al(i-Bu)3为助催化剂时,所得产物为无规共聚物;随着单体中Bd加入比例的增加,PB链节数均序列长度增加;随着Ip加入比例的增加,PI链节数均序列长度增加。

Nd （ vers ）3 （ simplied as Nd ）/ Al（i-Bu）2 H or Al（i-Bu）3 （simplied as A1）/ AI（i-Bu） 2 C1 （ simplied as C1） catalyst systems were applied to butadiene （ Bd ）/isoprene （ Ip ） copolymerization. The effects of different A1 and comonomer feed ratio on the polymerization behaviors were inves- tigated, the obtained copolymers were characterized by gel permeation chromatography （GPC） , Fourier transform infrared spectroscopy and nuclear magnetic resonance, and the monomer reactivity ratios during polymerization with the catalyst systems and sequence distributions of the obtained copolymers were further studied. The results showed that the mole fraction of cis-1,4-unit in both polybutadiene（PB） and polyiso- prene（PI） units exceeded 97%. The activity of the Al（i-Bu）2H-based system was obviously higher than that of A1 （i-Bu） 3-based system, the former afforded copolymers with lower number average molecular weights and broader molecular weight distributions and the GPC curves were bimodal, while the GPC curves of the copolymer obtained with the later＇system was monomodal. With increase of Bd in monomer feed, the mole fraction of cis-1,4-unit in PB of the copolymers were above 99%, whereas the cis-1,4- unit contents in PI slightly decreased with increase of Ip in monomer feed, and the composition of the co- polymer obtained by A1 （i-Bu） 3-based system practi- cally coincided with the comonomer composition. In the case of Al（i-Bu）2H-based system, the PB con- tent in the copolymer was slightly higher than that in monomer feed. In both catalyst systems, the monomer reactivity ratios exhibited similar tendency, Bd ten- ded to homopolymerization while Ip tended to copoly- merization with Bd. When AI（i-Bu）3 was used as cocatalyst, the copolymer was random. With the in- crease of Bd content in monomer feed, the number average sequence lengths of PB increased, and the number average sequence lengths of PI increased with an increase of the Ip content in monomer feed.