西北工业大学顾军渭团队报道了液晶工程聚二甲基硅氧烷——通过高介晶接枝密度提高固有导热性。相关研究成果于2025年1月20日发表在国际知名学术期刊《德国应用化学》。

电子设备功率和集成度的提高加剧了严重的热量积聚，推动了对聚二甲基硅氧烷（PDMS）等热界面材料更高固有导热性的需求。将介晶接枝到PDMS上可以提高其固有的导热性。然而，PDMS链的高稳定性限制了介晶的接枝密度，从而限制了热导率的提高。

该文提出了一种新的策略，通过液晶环硅氧烷和八甲基环四硅氧烷的开环共聚，有效地将介晶引入PDMS，提高接枝密度。通过非平衡分子动力学（NEMD）模拟研究了液晶聚二甲基硅氧烷（LC-PDMS）的接枝密度与本征导热系数之间的关系。基于模拟结果，合成了具有增强本征导热系数的LC-PDMS。

当介晶的接枝密度达到77.4%时，其固有导热系数（λ）增加到0.56 W/（m·K），比普通PDMS（0.20 W/（m·K））提高了180.0%。LC-PDMS还具有低介电常数（ε，2.69）、低介电损耗角正切（tanδ，0.0027）、高绝缘性能（体积电阻率，3.51×10¹³Ω·cm）、优异的热稳定性（耐热指数，217.8℃）和优异的疏水性（水接触角，137.4°），满足先进热界面材料的综合要求。

附：英文原文

Title: Liquid Crystal-Engineered Polydimethylsiloxane: Enhancing Intrinsic Thermal Conductivity through High Grafting Density of Mesogens

Author: Haitian Zhang, Yongqiang Guo, Yizhi Zhao, Qiuyu Zhu, Mukun He, Hua Guo, Xuetao Shi, Kunpeng Ruan, Jie Kong, Junwei Gu

Issue&Volume: 2025-01-20

Abstract: The increasing power and integration of electronic devices have intensified serious heat accumulation, driving the demand for higher intrinsic thermal conductivity in thermal interface materials, such as polydimethylsiloxane (PDMS). Grafting mesogens onto PDMS can enhance its intrinsic thermal conductivity. However, the high stability of the PDMS chain limits the grafting density of mesogens, restricting the improvement in thermal conductivity. This work proposes a new strategy to efficiently introduce mesogens onto PDMS through ring-opening copolymerization of liquid crystal cyclosiloxane and octamethylcyclotetrasiloxane, enhancing the grafting density. The relationship between the grafting density and intrinsic thermal conductivity of liquid crystal polydimethylsiloxane (LC-PDMS) is investigated by nonequilibrium molecular dynamics (NEMD) simulations. Based on the simulation results, LC-PDMS with enhanced intrinsic thermal conductivity is synthesized. When the grafting density of mesogens reaches 77.4%, its intrinsic thermal conductivity coefficient (λ) increases to 0.56 W/(m·K), showing a 180.0% improvement over ordinary PDMS (0.20 W/(m·K)). The LC-PDMS also exhibits the low dielectric constant (ε, 2.69), low dielectric loss tangent (tanδ, 0.0027), high insulation performance (volume resistivity, 3.51×1013 Ω·cm), excellent thermal stability (heat resistance index, 217.8℃) and excellent hydrophobicity (water contact angle, 137.4°), fulfilling the comprehensive requirements of advanced thermal interface materials.

DOI: 10.1002/anie.202500173

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202500173