稀土固体超强酸催化D4和D_4~H开环共聚合制备二甲基含氢硅油

Preparation of Methyl Hydrogen Silicone Fluids via Ring-Opening Copolymerization of D4 with D_4~H Catalyzed with Rare Earth Solid Super Acid

二甲基含氢硅油是制备二甲基硅橡胶不可缺少的原料,其性能对硅橡胶性能有较大影响。针对二甲基含氢硅油传统制备方法存在的缺点,本文中采用高活性、便于处理、能重复利用、低腐蚀性的稀土固体超强酸SO42-/Ti O2/Ln3+催化八甲基环四硅氧烷(D4)与1,3,5,7-四氢-1,3,5,7-四甲基环四硅氧烷(D4H)开环共聚合,制备了二甲基含氢硅油。系统考察了共聚合反应的规律,并探索了所得产物在加成型硅橡胶制备中的应用。结果表明,用SO42-/Ti O2/Nd3+做催化剂,[SO42-]=1.85 mol/L,[Nd3+]=0.05 mol/L时,在80℃聚合60 min,获得的二甲基含氢硅油收率为87.9%,相对分子质量为4.23×104,相对分子质量分布指数为3.07。当单体按照D4H/(D4H+D4)=30%,共聚单体与封端剂摩尔比为178.5∶1时,所得硅橡胶性能最佳。

Hydrogen silicone fluids generally served as cross-linking reagents for addition type liquid silicone rubber,which was widely used due to excellent performance. There are some disadvantages for hydrogen silicone fluids prepared by the traditional method. Here a convenient method for preparation of methyl hydrogen silicone fluids was explored:ring-opening copolymerization of octamethylcyclosiloxane( D4) with 2,4,6,8-tetramethylcyclotetrasiloxane( D4H) catalyzed with SO42-/Ti O2/Ln3 +. Features of the ring opening copolymerization were examined in detail. The reuse performance of the catalysts and the fabrication of the products for silicone gel were also investigated. The results exhibit that when the ring opening copolymerization is catalyzed by SO42-/Ti O2/Nd3 +with [SO42-]= 1. 85 mol/L,[Nd3 +]=0. 05 mol/L at 80 ℃ for 60 min,the product obtained is with yield = 87. 9 %,珚Mn= 4. 23 × 104,PDI = 3. 07. The silicone rubber has optimal performances when the methyl hydrogen silicone fluid is synthesized under the condition of D4H/( D4H+ D4) = 30% and n( D4H+ D4)/n( MM) = 178. 5∶ 1.