Fengyuan Zhang, Junliang Zhang*, Kuan Zhang, Xiao Zhong, Mukun He, Hua Qiu and Junwei Gu*. Highly Thermally Conductive Liquid Crystalline Epoxy Resin Vitrimers with Reconfigurable, Shape-Memory, Photo-Thermal, and Closed-Loop Recycling Performance. Advanced Science, 2024, 10.1002/advs.202410362. 2023IF=14.3.
https://onlinelibrary.wiley.com/doi/10.1002/advs.202410362
Abstract
The low thermal conductivity, poor toughness, and non-reprocessability of thermosetting epoxy resins severely restrict their applications and sustainable development in flexible electronics. Herein, liquid crystalline epoxy (LCE) and dynamic ester and disulfide bonds are introduced into the cured network of bisphenol A epoxy resin (E-51) to construct highly thermally conductive flexible liquid crystalline epoxy resin (LCER) vitrimers. LCER vitrimers demonstrate adjustable mechanical properties by varying the ratio of LCE to E-51, allowing it to transition from soft to strong. Typically, a 75 mol% LCE to 25 mol% E-51 ratio results in an in-plane thermal conductivity (λ) of 1.27 W m-1K-1, over double that of pure E-51 vitrimer (0.61 W m-1K-1). The tensile strength and toughness increase 2.88 folds to 14.1 MPa and 2.45 folds to 20.1 MJ m-3, respectively. Besides, liquid crystalline phase transition and dynamic covalent bonds enable triple shape memory and three-dimensional shape reconstruction. After four reprocessing cycles, λ and tensile strength remain at 94% and 72%, respectively. Integrating carbon nanotubes (CNTs) imparts photo-thermal effect and enables “on” and “off” switch under near-infrared (NIR) light to LCER vitrimer. Furthermore, the CNTs/LCER vitrimer displays light-induced actuation, self-repairing, and self-welding besides the closed-loop recycling and rapid degradation performance.
傳統熱固性環氧樹脂的低本征導熱性能、低韌性、不可再加工和回收性嚴重限制了其在柔性電子領域的應用和可持續發展。本研究將液晶環氧（LCE）與動態共價鍵（酯鍵和二硫鍵）引入到通用雙酚A型環氧樹脂（E-51）固化網絡中，制備了具有可再加工和回收性的柔性高本征導熱液晶環氧（LCER）類玻璃高分子。通過調節LCE與E-51的比例，LCER類玻璃高分子表現出可調控的機械性能，能夠從軟彈性體過渡到強韌體。當LCE與E-51的比例為75 mol%：25 mol%時，LCER兼具出色的導熱性能和機械性能，其面內導熱系數為1.27 W m-1 K-1，超過E-51（0.61 W m-1K-1）的兩倍；拉伸強度和韌性分別提高到14.1 MPa和20.1 MJ m-3，是E-51的2.88和2.45倍。同時，液晶獨特的相變性和動態共價鍵的可交換性賦予LCER三重形狀記憶、3D永久形狀重構等功能，經過四次重塑的導熱系數和拉伸強度可分別保持在原始性能的94%和72%。此外， LCER中0.5 wt%碳納米管（CNTs）的加入，使其具有穩定的光熱轉換性能，并能在808 nm的近紅外光下實現可控“開”和“關”切換。同時，CNTs/LCER 類玻璃高分子在近紅外光下能夠實現精準光致驅動、形狀記憶、局部自修復和自焊接，并可以實現閉環回收和快速降解。
論文亮點
1. 將LCE與動態共價鍵（酯鍵和二硫鍵）引入到通用雙酚A型環氧樹脂（E-51）固化網絡中，制備了具有可再加工和回收性的柔性本征高導熱液晶環氧樹脂（LCER）類玻璃高分子。
2.當LCE與E-51的摩爾比為3：1時，LCER的面內導熱系數為1.27 W m-1K-1，超過E-51（0.61 W m-1K-1）的兩倍；拉伸強度和韌性分別提高到14.1 MPa和20.1 MJ m-3，是E-51的2.88和2.45倍。
3. 含0.5 wt% CNTs的LCER具有優異的光熱轉換功能，且能在808 nm 的近紅外光源下實現可控“開”和“關”切換、精準光致驅動、形狀記憶、局部自修復和自焊接，并能實現閉環回收和快速降解。
第一作者：張峰源
郵件地址：zfy0019@mail.nwpu.edu.cn
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