Xiao Zhong, Kunpeng Ruan and Junwei Gu*. Enhanced Thermal Conductivities of Liquid Crystal Polyesters from Controlled Structure of Molecular Chains by Introducing Different Dicarboxylic Acid Monomers. Research, 2022, 2022: 9805686. 2021IF=11.036.（1区综合类Top期刊，2021中国最具国际影响力学术期刊）

https://doi.org/10.34133/2022/9805686

Enhancing thermal conductivity coefficient (λ) of liquid crystal polyesters would further widen their application in electronics and electricals. In this work, a kind of biphenyl-based dihydroxy monomer is synthesized using 4, 4’-biphenyl (BP) and triethylene glycol (TEG) as raw material, which further reacts with three different dicarboxylic acids (succinic acid, p-phenylenediacetic acid and terephthalic acid, respectively) by melt polycondensation to prepare intrinsically highly thermally conductive poly 4’, 4’’’-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) succinate (PEOS), poly 4’, 4’’’-[1, 2-ethanediyl-bis(oxy-2, 1-ethanediyloxy)]-bis(p-hydroxybiphenyl) p-phenyldiacetate (PEOP) and poly 4’, 4’’’-[1, 2-ethanediyl- bis(oxy-2, 1-ethanediyloxy)]- bis(p-hydroxybiphenyl) terephthalate (PEOT), collectively called biphenyl-based liquid crystal polyesters (B-LCPE). The results show that B-LCPE possess the desired molecular structure, exhibit smectic phase in liquid crystal range and semicrystalline polymers at room temperature, and possess excellent intrinsic thermal conductivities, thermal stabilities, and mechanical properties. λ of PEOT is 0.51 W/(m·K), significantly exceeds that of polyethylene terephthalate (0.15 W/(m·K)) which has similar molecular structure with PEOT, and also higher than that of PEOS (0.32 W/(m·K)) and PEOP (0.38 W/(m·K)). The corresponding heat resistance index (THRI), elasticity modulus and hardness of PEOT are 174.6oC, 3.6 GPa and 154.5 MPa, respectively, also higher than those of PEOS (162.2oC, 1.8 GPa and 83.4 MPa) and PEOP (171.8oC, 2.3 GPa and 149.6 MPa).

本文以4,4’-二羟基联苯（BP）和三乙二醇（TEG）为主要原料合成了一种联苯型液晶二羟基单体，并分别与丁二酸、1,4-亚苯基二乙酸和对苯二甲酸熔融缩聚，配合浇注成型工艺制备聚丁二酸{4'',4-[1,2-乙二基双(氧基-2,1-乙二氧基)]-双(对羟基联苯)}酯（PEOS）、聚1,4-亚苯基二乙酸{4'',4-[1,2-乙二基双(氧基-2,1-乙二氧基)]-双(对羟基联苯)}酯（PEOP）和聚对苯二甲酸{4'',4-[1,2-乙二基双(氧基-2,1-乙二氧基)]-双(对羟基联苯)}酯（PEOT）三种联苯型液晶聚酯（统称为B-LCPE）。结果表明，具有预期分子结构的B-LCPE表现出近晶相液晶性，室温下为半结晶性高分子；B-LCPE均表现出优异的本体导热性能、热稳定性和力学性能。PEOT具有最佳的综合性能，本体导热系数（λ）高达0.51 W/(m·K)，较分子结构相似的聚对苯二甲酸乙二醇酯（PET，λ为0.15 W/(m·K)）提升了240.0%，也优于PEOS（0.32 W/(m·K)）和PEOP（0.38 W/(m·K)）；相应的耐热指数（THRI）、弹性模量和硬度分别为174.6oC、3.6 GPa和154.5 MPa，也均优于PEOS（162.2oC、1.8 GPa、83.4 MPa）和PEOP（171.8oC、2.3 GPa和149.6 MPa）。