Islam Akherul Md, Lim Hongjin, You Nam-Ho, Ahn Seokhoon, Goh Munju, Hahn Jae Ryang, Yeo Hyeonuk, Jang Se Gyu
Department of Chemistry and Department of Bioactive Material Sciences and Research Institute of Physics and Chemistry, Chonbuk National University, Jeonju, Jeonbuk 561-756, Republic of Korea.
Department of Chemistry Education, Kyungpook National University, Daegu 41566, Republic of Korea.
ACS Macro Lett. 2018 Oct 16;7(10):1180-1185. doi: 10.1021/acsmacrolett.8b00456. Epub 2018 Sep 14.
A powerful strategy to enhance the thermal conductivity of liquid crystalline epoxy resin (LCER) by simply replacing the conventional amine cross-linker with a cationic initiator was developed. The cationic initiator linearly wove the epoxy groups tethered on the microscopically aligned liquid crystal mesogens, resulting in freezing of the ordered LC microstructures even after curing. Owing to the reduced phonon scattering during heat transport through the ordered LC structure, a dramatic improvement in the thermal conductivity of neat cation-cured LCER was achieved to give a value ∼141% (i.e., 0.48 W/mK) higher than that of the amorphous amine-cured LCER. In addition, at the same composite volume fraction in the presence of a 2-D boron nitride filler, an approximately 130% higher thermal conductivity (maximum ∼23 W/mK at 60 vol %) was observed. The nanoarchitecture effect of the ordered LCER on the thermal conductivity was then examined by a systematic investigation using differential scanning calorimetry, polarized optical microscopy, X-ray diffraction, and thermal conductivity measurements. The linear polymerization of LCER can therefore be considered a practical strategy to enable the cost-efficient mass production of heat-dissipating materials, due to its high efficiency and simple process without the requirement for complex equipment.
通过简单地用阳离子引发剂替代传统的胺类交联剂，开发出了一种增强液晶环氧树脂（LCER）热导率的有效策略。阳离子引发剂将连接在微观排列的液晶介晶元上的环氧基团线性编织在一起，即使在固化后也能使有序的LC微结构冻结。由于在通过有序LC结构的热传输过程中声子散射减少，纯阳离子固化的LCER的热导率得到了显著提高，比非晶态胺固化的LCER高出约141%（即0.48W/mK）。此外，在二维氮化硼填料存在且复合体积分数相同时，观察到热导率提高了约130%（在60体积%时最大约为23W/mK）。然后，通过差示扫描量热法、偏光显微镜、X射线衍射和热导率测量等系统研究，考察了有序LCER对热导率的纳米结构效应。因此，由于LCER的线性聚合效率高且工艺简单，无需复杂设备，可被视为一种实现散热材料经济高效大规模生产的实用策略。
