Haitian Zhang, Yongqiang Guo, Yizhi Zhao, Qiuyu Zhu, Mukun He, Hua Guo, Xuetao Shi, Kunpeng Ruan*, Jie Kong and Junwei Gu*. Liquid Crystal-Engineered Polydimethylsiloxane: Enhancing Intrinsic Thermal Conductivity through High Grafting Density of Mesogens. Angewandte Chemie International Edition, 2025, 10.1002/anie.202500173. 2023IF=16.1. （1區(qū)化學(xué)Top期刊）
https://doi.org/10.1002/anie.202500173
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, 217.8oC) and excellent hydrophobicity (water contact angle, 137.4o), fulfilling the comprehensive requirements of advanced thermal interface materials.
電子產(chǎn)品的高功率化和高集成化使其中電子元器件的熱量積聚問(wèn)題愈發(fā)嚴(yán)峻，進(jìn)而對(duì)聚二甲基硅氧烷（PDMS）等熱界面材料的本征導(dǎo)熱性能提出了更高的要求。在大分子鏈上接枝液晶基元有利于PDMS本征導(dǎo)熱性能的提升，但是PDMS主鏈穩(wěn)定性過(guò)高，不易發(fā)生反應(yīng)，導(dǎo)致液晶基元的接枝密度過(guò)低，本征導(dǎo)熱性能提升有限。本文提出通過(guò)液晶環(huán)硅氧烷與八甲基環(huán)四硅氧烷開(kāi)環(huán)共聚進(jìn)而在PDMS上高效引入液晶基元、提升液晶基元接枝密度的新策略。首先通過(guò)非穩(wěn)態(tài)分子動(dòng)力學(xué)模擬（NEMD）研究液晶基元接枝密度與液晶聚二甲基硅氧烷（LC-PDMS）本征導(dǎo)熱性能的內(nèi)在聯(lián)系，進(jìn)而以模擬結(jié)果為導(dǎo)向，基于開(kāi)環(huán)共聚法成功制備了本征高導(dǎo)熱LC-PDMS。當(dāng)LC-PDMS分子鏈上液晶基元接枝密度達(dá)到77.4%時(shí)，其本征導(dǎo)熱系數(shù)（λ）高達(dá)0.56 W/(m·K)，較通用PDMS（0.20 W/(m·K)）提升了180.0%。該類本征高導(dǎo)熱LC-PDMS還兼具低介電常數(shù)（ε，2.69）和介電損耗角正切值（tanδ，0.0027）、高絕緣性能（體積電阻率高達(dá)3.51×1013 Ω·cm）、優(yōu)異熱穩(wěn)定性（耐熱指數(shù)高達(dá)217.8℃）和出色疏水性（水的接觸角高達(dá)137.4o），可滿足高端熱界面材料的綜合性能需求。
論文亮點(diǎn)
1. 通過(guò)NEMD研究了液晶基元接枝密度與LC-PDMS本征導(dǎo)熱性能的內(nèi)在聯(lián)系，進(jìn)而以模擬結(jié)果為導(dǎo)向，基于開(kāi)環(huán)共聚法成功制備了本征高導(dǎo)熱LC-PDMS。
2. 當(dāng)LC-PDMS分子鏈上液晶基元接枝密度達(dá)到77.4%時(shí)，其本征λ高達(dá)0.56 W/(m·K)，較通用PDMS（0.20 W/(m·K)）提升了180.0%。
3. LC-PDMS兼具低介電常數(shù)和介電損耗角正切值、高絕緣性能、優(yōu)異熱穩(wěn)定性和出色疏水性，可滿足高端熱界面材料的綜合性能需求。
第一作者：張海天郵件地址：[email protected]
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