熔融酯交换法合成氢化双酚A型聚碳酸酯

Synthesis of Hydrogenated Bisphenol A Polycarbonate via Melt Transesterification

以氢化双酚A为反应单体,通过与碳酸二苯酯熔融酯交换成功合成了氢化双酚A型聚碳酸酯,并考察了催化剂的种类及其浓度、单体配比、酯交换时间、缩聚温度等工艺条件对产品分子量、分子结构、热性能及外观等的影响。结果表明,氢化双酚A因二级醇的弱碱特性,在酯交换反应中难以解离成亲核试剂,导致其反应活性较双酚A低;与其他碱金属盐或碱土金属盐催化剂相比较,LiCl具有较高的催化活性。当催化剂摩尔分数为0.01%,碳酸二苯酯和氢化双酚A的物质的量之比为1.01∶1,且酯交换反应时间为2 h,缩聚温度为250℃时,合成的氢化双酚A型聚碳酸酯的数均分子量(M_n)可达1.12×10~4,玻璃化转变温度为160℃,且色泽优异。

Application of traditional polycarbonates is forbidden in some fields due to the fact that bisphenol A(BPA) is not UV-resistant and it is usually regarded as an exogenous estrogen. As a result, the development of alternative polycarbonates has attracted wide attention. Here hydrogenated bisphenol A(HBPA) polycarbonate was successfully synthesized by melt polycondensation between HBPA and diphenyl carbonate(DPC). The influences of factors, such as the types and concentrations of catalysts, monomer ratio, transesterification time and temperature on the molecular weight,molecular structure, thermal properties and appearance of the products were investigated. The results show that, as a secondary alcohol bearing weak alkalinity, HBPA is difficult to dissociate into nucleophile, which leads to a lower reactivity compared with BPA. An alkaline catalyst with strong coordination ability, such as LiCl, exhibits high catalytic activity. With the addition of the catalyst of 0.01%(molar fraction), the molar ratio of DPC to HBPA at 1.01∶1,transesterification reaction time for 2.0 h, and the polycondensation temperature at 250 ℃, the number average molecular weight of the synthesized HBPA polycarbonate is 1.12×10~4 with T_g of 160 ℃, showing good color property.