Kuan Zhang, Junliang Zhang*, Lin Dang, Yuhao Wu, Mukun He, Hua Guo, Xuetao Shi, Hua Qiu and Junwei Gu*. High intrinsic thermal conductivity and low dielectric constant of liquid crystalline epoxy resins with fluorine-containing semi-IPN structures. Science China Chemistry, 2025, 10.1007/s11426-024-2504-y. 2023IF=10.4.（1区化学Top期刊，中国科技期刊卓越行动计划-领军类期刊项目）

https://doi.org/10.1007/s11426-024-2504-y

Abstract

High integration, high frequency, high power, and miniaturization of electrical and electronic devices have raised higher demands for epoxy resins with both high intrinsic thermal conductivity and low dielectric properties. Herein, a series of linear fluorinated epoxy copolymers (poly(PFS-co-GMA)) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly(PFS-co-GMA) was introduced into the cross-linked network of a biphenyl-based liquid crystalline epoxy (LCE) by forming a semi-interpenetrating polymer network (semi-IPN). The prepared liquid crystalline epoxy resins (LCERs) simultaneously exhibited high intrinsic thermal conductivity and low dielectric properties. The molar mass and mass fraction of poly(PFS-co-GMA) were found to have a profound effect on the thermal conductivity and dielectric performance of LCERs. For instance, poly(PFS-co-GMA) with the number average molar mass (Mn) of 4300 and 7800 g/mol showed a decreasing effect on the thermal conductivity (λ) of LCERs whereas the polymer with Mn of 10500 g/mol enhanced the λ. The intrinsic λ of LCERs increased to a remarkable highest value of 0.40 W/(m·K), which was twice that of conventional epoxy resin (0.20 W/(m·K)). In addition, introducing poly(PFS-co-GMA) would significantly decrease the dielectric constant (ε) and dielectric loss tangent (tanδ) of LCERs from 3.44 and 0.035 to 2.49 and 0.001 at 1 MHz, respectively. Notably, the ε and tanδ could remain relatively stable over a wide range of frequencies and temperatures up to 120℃. Additionally, the semi-IPN structure enhanced the hardness, electrical insulation, and hydrophobicity of LCERs.

随着电子电气设备的高集成化、高频率化、高功率化和微型化，兼具本征高导热系数和低介电常数环氧树脂的需求量越来越大。本文通过可逆加成-断裂链转移（RAFT）聚合合成一系列线性含氟环氧共聚物poly(PFS-co-GMA)，并将其与联苯型液晶环氧单体（LCE）共聚构建具有半互穿聚合物网络（semi-IPN）结构的液晶环氧树脂（LCERs）。联苯液晶基元间的相互堆叠、氟原子对液晶有序结构的促进作用以及semi-IPN结构共同促使环氧树脂固化网络内部有序结构的形成，有效抑制声子散射，降低分子极化率，同步赋予环氧树脂本征高导热系数（λ）以及低介电常数（ε）和低介电损耗角正切（tanδ）。研究表明，poly(PFS-co-GMA)的分子量和质量分数对LCERs的导热性能和介电性能有着显著影响。当poly(PFS-co-GMA)的数均分子量（Mn）为4300 g/mol和7800 g/mol时，其使LCERs的本征λ降低；而当Mn为10500 g/mol时，LCERs的本征λ显著提升，最高可达0.40 W/(m·K)，是传统环氧树脂（0.20 W/(m·K)）的2倍。此外，引入poly(PFS-co-GMA)会显著降低LCERs的ε和tanδ，其在1 MHz下分别从3.44和0.035降至2.49和0.001。同时，ε和tanδ可以在较宽温度（20~120℃）范围内保持相对稳定。此外，semi-IPN结构提升了LCERs的硬度、电绝缘性和疏水性。

论文亮点

1. 将含氟线性聚合物poly(PFS-co-GMA)引入到联苯型液晶环氧的固化网络中构建半互穿聚合物网络结构，同步赋予液晶环氧树脂（LCERs）本征高导热系数和低介电常数。

2. 当poly(PFS-co-GMA)的Mn为10500 g/mol且质量分数为15 wt%时，LCERs具有最高的本征λ以及最低的ε和tanδ，其λ为0.40 W/(m·K)，是E-51（0.20 W/(m·K)）的2倍。

3. LCERs的ε和tanδ分别从E-51的3.44和0.035降低至2.49和0.001（1 MHz），并在较宽温度（20~120℃）范围内保持相对稳定；LCERs兼具优异的硬度、电绝缘性和疏水性。

第一作者：张宽邮件地址：zhangkuan@mail.nwpu.edu.cn

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