Kuan Zhang, Junliang Zhang*, Jiahao An and Junwei Gu*. Unravelling Intrinsic Thermal Conduction Mechanism through Phonon Transport Pathway Engineering of Long-Range Ordered Block Copolymers. Chemical Science, 2026, 10.1039/D6SC01804A. 2024IF=7.5.（1区化学Top期刊）

https://doi.org/10.1039/D6SC01804A

Abstract

Highly thermally conductive polymers are playing essential roles in various electronics-related fields. However, the mechanism underlying thermal conduction remains hitherto elusive. Herein, the intrinsic thermal conduction mechanism of polymers was disclosed by rational molecular structural design and precise synthesis through reversible addition-fragmentation chain transfer (RAFT) polymerization. By precisely controlling the spatial distribution and sequence of cyanobiphenyl-based liquid crystalline (LCx) monomer and glycidyl methacrylate (GMA, epoxy-containing unit), as well as length of flexible segment (-CH₂-)_x in LCx, block copolymers PLCx_m-b-PGMA_n with multi-level long-range ordered structures were generated. Specifically, microstructures of hexagonally packed cylinder-like (HEX-like), lamellar-like (LAM-like), and inverted hexagonally packed cylinder-like (Inverted HEX-like) were effectively constructed as the flexible segment of -CH2- was increased to 11 ((-CH₂-)₁₁, LC11). It is noteworthy that increasing the ratio of LC11 was highly beneficial for enhancing thermal conductivity. Moreover, compared with HEX-like and inverted HEX-like morphologies, which exhibited numerous thermal interfaces, the LAM-like morphology was able to construct long-range phonon transport pathways and reduce phonon scattering through the synergistic effect of microphase separation-driven confined assembly with semicrystalline structure and supramolecular assembly, thereby exhibiting higher thermal conductivity. This study elucidates the thermal transport mechanism at molecular levels by experiments and simulations, highlighting the crucial role of multiscale chain alignment and long-range ordered structures synergistically enhancing phonon propagation in polymers.

本征高导热聚合物材料在电子、电气领域中发挥着重要作用。本文从分子结构设计出发，通过可逆加成-断裂链转移（RAFT）聚合精准合成一系列嵌段聚合物，揭示了聚合物多尺度分子链结构对其本征导热性能的影响。通过精确调控氰基联苯液晶单体（LCx）与甲基丙烯酸缩水甘油酯单体（GMA）在聚合物分子链的分布与序列，以及LCx中柔性链段(-CH₂-)x的长度，成功构筑了具有多级长程有序结构的嵌段共聚物PLCx_m-b-PGMA_n。当LCx柔性链段中含有11个-CH₂-单元（LC11）时，PLC11_m-b-PGMA_n形成了类六方堆积柱状相（HEX-like）、类层状相（LAM-like）以及反类六方堆积柱状相（Inverted HEX-like）等微观相结构。结果表明，提高LC11在聚合物中的比例对提升其本征导热性能具有重要作用。与具有大量热界面的HEX-like和Inverted HEX-like形貌相比，LAM-like形貌能够构建长程有序声子传递路径，并且通过微相分离驱动的受限组装、半晶结构增强的有序堆积以及超分子组装的协同作用有效抑制声子散射，显著促进声子热传递。本研究通过实验与分子模拟相结合，从分子水平探究聚合物的本征导热机理，揭示了多尺度链取向与长程有序结构对构建声子传递路径并提升聚合物导热性能的关键作用。

第一作者：张宽

邮件地址：zhangkuan@mail.nwpu.edu.cn