铁系催化剂上合成高乙烯基聚丁二烯的研究 Ⅰ.三苯基磷酸酯的影响

Investigation on Synthesis of High Vinyl Polybutadiene with Iron-Based Catalysts Ⅰ. Effect of Triphenyl Phosphate

考察了不同磷化合物、催化剂组成、加料方式及反应温度对 2 乙基己酸铁 (Fe) 三异丁基铝 (Al)催化剂上 1,3 丁二烯(BD)聚合反应的影响 ,发现以三苯基磷酸酯 (P)为配体的铁系催化剂在己烷中 ,n(Fe) ∶n(P) ∶n(Al) =1∶4∶2 5 ,加料方式为BD+Fe +P +Al和θ =5 0℃的条件下具有最高的催化活性 ,聚合产物的分子量分布指数为 2 5 0 ,GPC淋出曲线呈单峰分布 ,表明该催化剂具有单一的活性中心 .经NMR ,GPC ,DSC和XRD测定 ,所得聚丁二烯具有较高的 1,2 结构含量 (95 % ) ,较高的间同立构规整度 (95 % ) ,较高的结晶度 (6 8% ) ,较高的分子量 (Mn=7 4× 10 5)及较高的熔点 (189℃ ) .反应条件对聚合产物的立构规整性无明显影响 .

Butadiene (BD) polymerization catalyzed by iron (2-ethyl hexanoate) 3 (Fe)-triisobutyl aluminium (Al)-triphenyl phosphate (P) was investigated, in regard to different phosphorous compounds, n(P) / n(Fe) and n(Al) / n(Fe) ratios, catalyst preparation method and reaction temperature. Though the addition of triphenyl phosphine, triethyl phosphite, triphenyl phosphite, triethyl phosphate or tributyl phosphate as a ligand to the catalyst system gave rise to oil-like oligomers, the addition of dialkyl phosphite (diethyl phosphite and diphenyl phosphite) or triphenyl phosphate as a ligand produced polybutadiene with high 1,2-unit contents. The activity of the iron-based catalyst with triphenyl phosphate remarkably promoted with the increase of the reaction temperature from 0 to 50 ℃. The optimum activity achieved at n(Fe) ∶ n(P) ∶ n(Al) =1∶4∶25 with an addition order of BD+Fe+P+Al. The polydispersity index was 2.50 and the unimodal GPC curve of the polymer indicated that the catalytic system involved a single active site at 50 ℃. According to the results of NMR, XRD, GPC and DSC, the product polymer possessed high 1,2-unit content (95%), high syndiotacticity (95%), high crystallinity (68%), high molecular mass (M n=7.4×10 5), and high melting point (189 ℃). Regardless of reaction conditions, the 1,2-unit content and syndiotacticity of the polymer obtained at 50 ℃ stayed around 95%, indicating the high stability of stereospecificity of the catalyst.