单茂钪催化苯乙烯衍生物与异戊二烯共聚合的研究

Copolymerization of Styrene Derivatives and Isoprene Catalyzed by Half-sandwich Scandium Complex

研究了单茂钪(C^5Me^4SiMe^3)Sc(CH^2C^6H^4NMe^2-o)^2催化异戊二烯(IP)与苯乙烯衍生物对氯苯乙烯(St-Cl)、4-二甲基硅氢苯乙烯(St-SiHMe^2)共聚合的性能,通过NMR、GPC和DSC对所获共聚物的微观结构和热性能进行表征分析.结果表明,在室温氯苯溶剂中,改变IP和苯乙烯衍生物的用量,单茂钪均可以催化IP与St-Cl、St-SiHMe^2共聚合,获得了组成可控(IP含量21 mol%~95 mol%)、高分子量(M^n=3.1×10^4~15.9×10^4)、窄分布(M^w/M^n=1.21~1.92)的IP/St-Cl和IP/St-SiHMe^2两类共聚物,共聚物中IP形成1,4-和3,4-结构单元,苯乙烯衍生物形成间规聚合结构.苯乙烯衍生物取代基的电负性直接影响共聚合活性和共聚物的序列分布.IP与St-SiHMe^2共聚合活性(10^5 g聚合物mol^Sc^-1 h^-1)远高于IP与St-Cl共聚合活性(10^4 g聚合物mol ^Sc^-1 h^-1);相同共聚合条件下St-SiHMe^2的插入率高于St-Cl.单茂钪催化IP与St-Cl共聚合获得了梯度共聚物,IP/St-Cl共聚物具有源自聚IP链段的玻璃化转变温度(T^g=-1~5℃)和源自间规聚St-Cl链段的熔点(T^m=314~318℃).单茂钪催化IP与St-SiHMe2共聚合获得无规共聚物,IP/StSiHMe^2共聚物具有一个Tg,该Tg值(12~82℃)随St-SiHMe^2含量(13 mol%~79 mol%)的增加而线性增加.

The copolymerization of isoprene and styrene derivatives such as p-chlorostyrene(St-Cl)and 4-dimethylsilyl styrene(St-SiHMe^2)catalyzed by the half-sandwich scandium complex(C^5Me^4SiMe^3)Sc-(CH^2C^6H^4NMe^2-o)^2 have been studied in this paper.The microstructures and thermal properties of the obtained copolymers were characterized by NMR,GPC and DSC.These results showed that the IP/St-Cl and IP/St-SiHMe2 copolymers with controllable IP content(21 mol%-95 mol%),high molecular weight(M^n=3.1×10^4-15.9×10^4)and narrow molecular weight distribution(M^w/M^n=1.21-1.92)were conveniently obtained by changing the feed ratio of IP to styrene derivatives in chlorobenzene at room temperature,in which IP was in 1,4-and 3,4-structure units and the styrene derivatives had a syndiotactic structure.The electronegativity of substituents on the styrene derivatives directly affected the copolymerization activity and the comonomer distribution sequences in the resulting copolymers.The copolymerization activity of IP and St-SiHMe^2(10^5 g polymer mol^Sc^-1 h^-1)was much higher than that of the copolymerization of IP and St-Cl(10^4 g polymer mol^Sc^-1 h^-1),and the incorporation content of St-SiHMe^2 was also higher than that of St-Cl under the same conditions.The copolymerization of IP and St-Cl afforded gradient copolymers with a glass transition temperature(T^g=-1-5°C)originating from poly(IP)segment and a melting point(T^m=314-318°C)originating from syndiotactic poly(St-Cl)segment.The copolymerization of IP and St-SiHMe^2 afforded the random copolymers with a single T^g(12-82°C)which increased with the enhance of St-SiHMe^2 content(13 mol%-79 mol%).