以三光气(BTC)、3,3',5,5'-四甲基双酚A(TMBPA)、双酚A(BPA)为原料,采用界面缩聚法合成了四甲基双酚A型共聚聚碳酸酯(PC)。采用傅里叶红外光谱分析、核磁共振、X射线衍射等方式证实了聚合物的化学结构,用差示扫描量热法、热重分析等测试方法对聚合物的热性能、介电性能进行表征。结果表明,合成的共聚PC的玻璃化温度随着TMBPA/BPA摩尔比的增加而增加,最高达到了193.5℃;在氮气中5%热分解温度出现先降低后升高的现象,但最低也达到了400.4℃;线性膨胀系数由73.89×10^-6K^-1降至32.91×10^-6K^-1。最后研究了四甲基双酚A型共聚PC的介电性能和光学性能,在10GHz条件下,其最小介电常数为2.65、最小介电损耗角正切值为0.00522。这表明,四甲基双酚A型共聚PC是一种具有低介电常数和优良耐高温性能的高光学透明材料。

Tetramethylbisphenol A-type copolymer polycarbonate (PC) was synthesized by an interfacial polycondensation method using triphosgene (BTC),3,3',5,5'-tetramethylbisphenol A (TMBPA) and bisphenol A (BPA) as raw materials.The chemical structure of the polymer was confirmed by Fourier-transform infrared spectroscopy (FT-IR),nuclear magnetic resonance (¹H-NMR) and X-ray diffraction (XRD),and the thermal and dielectric properties of the polymer were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).The results showed that the glass transition temperature (T_g) of the synthesized copolymer PC increased with the increase of the molar ratio of TMBPA/BPA,reaching a maximum of 193.5℃.In nitrogen.The 5% thermal decomposition temperature (T_d) decreased first and then increased,but the lowest T_d also reached 400.4℃.The coefficient of linear expansion (CET) decreased from 73.89×10^-6K^-1 to 32.91×10^-6K^-1.Finally,the dielectric and optical properties of the tetramethylbisphenol A-type copolymer PC were studied,and the minimum dielectric constant (ε) was 2.65 and the minimum dielectric loss tangent (tanδ) was 0.00522 at 10GHz.These results indicated that tetramethylbisphenol A-type copolymer PC was a highly optically transparent material with low dielectric constant and excellent high-temperature resistance.