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Fengyuan Zhang, Wenqing Zhang, Kuan Zhang, Junliang Zhang*, Junwei Gu*. Reprogrammable and chemically degradable liquid crystalline epoxy vitrimers with high intrinsic in-plane thermal conductivity. Acta Physico-Chimica Sinica, 2026, 10.1016/j.actphy.2026.100454. 2025IF=13.5.

https://doi.org/10.1016/j.actphy.2026.100454

Abstract

  The inherently low thermal conductivity and insufficient recyclability of epoxy thermosets pose substantial challenges to their sustainable development. Herein, reprogrammable, chemically degradable, and intrinsically highly thermally conductive liquid crystalline epoxy vitrimers (LCERs) were developed. These LCERs were constructed with covalent adaptable networks through introducing dual dynamic disulfide and ester bonds into the topological networks of cured liquid crystalline epoxies (LCEs). LCEs were designed to contain biphenyl mesogens connected with varied ethylene glycol oligomer spacers (–(OC₂H₄)_x–). Due to the cooperation of rigid biphenyl units and flexible –(OC₂H₄)_x–, which facilitated dense and orderly molecular packing and efficient phonon transport, LCERs achieved significantly enhanced intrinsic thermal conduction capability and mechanical performance. The resulting LCER2 (x = 2) demonstrated the highest intrinsic in-plane thermal conductivity of 1.95 W/(m·K), representing 319% that of conventional epoxy. Meanwhile, its tensile strength reached up to 27.1 MPa. Importantly, LCERs exhibited thermally reprogrammable triple-shape-memory behavior, reprocessability, and chemical degradability enabled by a covalent adaptable network containing exchangeable disulfide and ester linkages. The degraded products enabled considerably upgraded thermal conductivity and tensile strength of conventional epoxy by 90% and 158%, respectively. The results show that crystallinity is not the sole determinant of intrinsic thermal conductivity of epoxy resin. The continuity of ordered structures, molecular packing density, and chain conformation also play important roles. This study demonstrates a significant breakthrough in the bottleneck of low thermal conduction and unrecyclable characteristics of epoxies, providing a critical guidance for developing sustainable cutting-edge thermal management materials.

  针对环氧树脂本征低导热系数且难回收的问题，本文构筑了一类兼具可编程、可重复加工、可化学降解的本征高导热液晶环氧类玻璃高分子。通过在液晶环氧固化网络中引入可交换的二硫键和酯键构建动态共价网络；设计由不同长度乙二醇寡聚链段（–(OC₂H₄)_x–）连接的联苯介晶基元以促进分子致密有序堆积和高效声子传输。得益于刚性联苯单元与柔性链段的协同作用，液晶环氧类玻璃高分子的本征导热性能和力学性能均得到显著提升。当x=2时，其面内导热系数最高，达到1.95 W/(m·K)，为传统环氧树脂的319%，对应的拉伸强度也达27.1 MPa。液晶环氧类玻璃高分子还表现出热可编程的三重形状记忆行为、可再加工及可降解性能，其降解产物可使传统环氧树脂的导热系数和拉伸强度分别提高90%和158%。环氧树脂的本征热导率并非仅由结晶度决定，其分子堆积致密性、有序结构连续性及链构象同样起着重要的作用。本研究为突破环氧树脂低本征导热系数和难回收的瓶颈难题，以及开发可持续热管理材料提供了新的设计思路。

第一作者：张峰源

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