含双酚芴聚碳酸酯的合成与光学性能

Synthesis and Optical Properties of Polycarbonates Copolymerized with Bisphenol Fluorene Moiety

将具有负双折射系数的双酚芴{9,9-二[4-(2-羟乙氧基)苯基]芴,BPEF}与双酚A(BPA)共聚,制备本征双折射率接近零的含双酚芴聚碳酸酯(共聚PC).研究发现,碱性强、pKa值大的催化剂可以缩小BPA和BPEF的活性差异,有利于制备高分子量含双酚芴聚碳酸酯,缩聚温度为265℃、缩聚时间为40 min时产物具有较高的分子量和较低的黄变指数.BPEF和BPA投料比(摩尔比)为40/60时共聚体系的重均分子量可达39800,1H NMR和13C NMR测试证明分子链呈无规共聚结构.随着BPEF含量的上升,共聚PC的折射率从1.586提高到1.639,本征双折射率从0.1948下降到−0.0102.当BPEF摩尔分数为87%时,共聚PC的本征双折射率低至0.0028,非常接近零双折射.

To reduce the birefringence of bisphenol A polycarbonate(BPA-PC),we intended to copolymerize bisphenol fluorene(BPEF)with BPA to prepare a copolycarbonate with intrinsic birefringence close to 0.We observed that catalysts with a large basic pKa value can reduce the difference in reactive activity between BPA and BPEF,thus increasing the molecular weight of copolycarbonates.When the polycondensation temperature is 265℃and time is 40 min,the weight-average molecular weight of the synthesized PC with a feed molar ratio of BPEF/BPA of 40/60 reaches 39800.1H NMR and 13C NMR analysis testify that all products are random copolymers.Increasing the content of BPEF leads to a high refractive index and a low birefringence value.When the BPEF molar fraction is 87%,the intrinsic birefringence is approximately 0.0028,which is very close to zero birefringence.