writer：Qingqing Kong, Junliang Zhang,* Kuan Zhang, Shuangshuang Wang, Mukun He, Yongqiang Guo, Junwei Gu*
keywords：Azobenzene, Intrinsic thermal conductivity, Photoresponsive actuation, RAFT polymerization, Thermally conductive polymers
source：期刊
Issue time：2025年

Qingqing Kong, Junliang Zhang,* Kuan Zhang, Shuangshuang Wang, Mukun He, Yongqiang Guo, Junwei Gu*. Recyclable Side-Chain Azobenzene-Based Semicrystalline Polymer Films with Outstanding Intrinsic Thermal Conductivity and Photoresponsive Actuation. Angewandte Chemie International Edition, 2025, 10.1002/anie.202512721. 2024IF=16.9（1区化学TOP期刊）

https://doi.org/10.1002/anie.202512721

Abstract

Conventional polymers exhibit low intrinsic thermal conductivity (λ) of 0.1~0.5 W/(m·K) due to disordered chain arrangements, failing to meet the heat dissipation demands of high-power flexible electronic devices. This study proposes a molecular level design strategy for side-chain azobenzene-containing semicrystalline polymers that demonstrate exceptional intrinsic thermal conductivity with photoresponsive actuation and recyclability. By precisely regulating the spatial distribution and content of azobenzene groups and hydrogen-bond network along the polymer chain through controlled radical polymerization, a thermal conduction network featuring “high-efficiency conduction within crystal domains and low-resistance interfacial connections” was constructed. Azobenzene moieties self-assemble into highly oriented crystalline domains through π–π stacking, where their dense packing significantly enhances phonon coupling efficiency and increases phonon mean free paths. Concurrently, the dynamic reversibility of hydrogen bonds guides domain-boundary molecular chains to form gradual phase transitions, suppressing phonon scattering at amorphous-crystalline interfaces and improving phonon transport efficiency. The film of random copolymer with 35 azobenzene units achieves an outstanding highest intrinsic λ of 2.01 W/(m·K), representing a substantial improvement over its block copolymer counterpart (with a higher crystallinity) and traditional polymers. Additionally, the photoisomerization property of azobenzene endows the material with light-controlled dynamic deformation capabilities. Meanwhile, the noncrosslinked polymer films feature easy recyclability/reprocessability.

传统聚合物由于分子链排列无序，其本征热导率较低，无法满足高功率柔性电子器件的散热需求。本研究提出一种利用可控自由基聚合调控聚合物分子结构的设计策略，制备具有优异本征导热性能的偶氮苯聚合物。通过可逆加成-断裂链转移（RAFT）聚合，精确调控聚合物链上偶氮苯基元的空间分布、聚合度以及氢键网络，构建具有“晶域内高效传导、界面低阻连接”的导热网络。偶氮苯基元通过π-π堆积自组装形成高度取向的晶域，显著提高声子耦合效率，增加了声子平均自由程。氢键的动态可逆性使域边界分子链形成渐变过渡，抑制非晶区-晶区界面处的声子散射，提高声子传输效率。研究表明，聚合物本征热导率不随其结晶度提高而持续上升，同时受其晶粒大小以及晶区与非晶区界面形貌影响。当偶氮苯基元在聚合物链上无规分布且聚合度为35时，其结晶度为18.6%，由此制备的薄膜本征导热系数高达2.01 W/(m·K)，高于具有相同单体组成但结晶度更高（23.7%）的嵌段共聚物的1.86 W/(m·K)。同时，偶氮苯的光异构化特性赋予其光控动态形变能力，其非交联特性也较动态共价键交联聚合物具有更优的回收/再加工性能。本研究为先进热管理材料的开发提供了关键理论指导，有望应用于仿生驱动器、柔性电子、软体机器人、光热转换和信息存储等领域。