窄分布双氢基封端硅氧烷低聚物的合成

Synthesis of Dihydro Terminated Polydimethylsiloxanes with Narrow Distribution

以八甲基环四硅氧烷、1，1，3，3-四甲基二氢基二硅氧烷（俗称含氢双封头）为原料，以浓硫酸为催化剂，采用平衡聚合的方法制备了不同摩尔质量的双氢基封端硅氧烷低聚物（HMDn MH）。采用红外光谱、核磁共振氢谱、凝胶渗透色谱、气相色谱等分析方法对产物结构进行了确认和表征。研究了反应温度、反应时间、催化剂用量等对反应的影响。较佳反应条件为：平衡反应温度35℃、浓硫酸质量分数1．5％、反应时间6h。在此条件下可获得较高收率的窄摩尔质量分布（1．22～1．39）的HMDn MH.D4和HMMH的质量比影响产物的摩尔质量。D4含量越高（或HMMH含量越低）则产物的摩尔质量越大，且与设计值之间的偏差越大。HMDn MH的特性黏数与数均摩尔质量的自然对数之间呈线性关系，其相关系数为R2=Q994，相关性极好。

Dihydro terminated polydimethylsiloxane （HMDnMH） with different molecular weights were prepared by 1,1,3,3-tetramethyldisiloxane （HMMH） and octamethylcyclotetrasiloxane （ D4 ）. The reaction was catalyzed by concentrated sulfuric acid. As characterized by IR, ^1H NMR, GPC, GC and Ukrainian-style viscometer, we explored the influence of various reaction temperature and time, amount of catalyst on the poly- merization reaction. Results show that HMDnMH is obtained with higher yield of narrow distribution （ 1.22 ~ 1.39 ） at a copolymerization temperature of 35~C with the amount of concentrated sulfuric acid of 1.5 wt% for 6 h. The mass of D4 and HMMH affect the molar mass of the product. The higher D4 （ or the lower HMMH）, the greater the molar mass of the product, and the greater the deviation between the target value. The viscosity characteristics of HMDnMH and the natural logarithm of number average molar mass is linear, with the excel- lent correlation coefficient of R2 = 0. 994.