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(tǒng)熱固性環(huán)氧樹脂的低本征導(dǎo)熱性能、低韌性、不可再加工和回收性嚴(yán)重限制了其在柔性電子領(lǐng)域的應(yīng)用和可持續(xù)發(fā)展。本研究將液晶環(huán)氧（LCE）與動態(tài)共價鍵（酯鍵和二硫鍵）引入到通用雙酚A型環(huán)氧樹脂（E-51）固化網(wǎng)絡(luò)中，制備了具有可再加工和回收性的柔性高本征導(dǎo)熱液晶環(huán)氧（LCER）類玻璃高分子。通過調(diào)節(jié)LCE與E-51的比例，LCER類玻璃高分子表現(xiàn)出可調(diào)控的機(jī)械性能，能夠從軟彈性體過渡到強韌體。當(dāng)LCE與E-51的比例為75 mol%：25 mol%時，LCER兼具出色的導(dǎo)熱性能和機(jī)械性能，其面內(nèi)導(dǎo)熱系數(shù)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(tài)共價鍵的可交換性賦予LCER三重形狀記憶、3D永久形狀重構(gòu)等功能，經(jīng)過四次重塑的導(dǎo)熱系數(shù)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(wěn)定的光熱轉(zhuǎn)換性能，并能在808 nm的近紅外光下實現(xiàn)可控“開”和“關(guān)”切換。同時，CNTs/LCER 類玻璃高分子在近紅外光下能夠?qū)崿F(xiàn)精準(zhǔn)光致驅(qū)動、形狀記憶、局部自修復(fù)和自焊接，并可以實現(xiàn)閉環(huán)回收和快速降解。
論文亮點
1. 將LCE與動態(tài)共價鍵（酯鍵和二硫鍵）引入到通用雙酚A型環(huán)氧樹脂（E-51）固化網(wǎng)絡(luò)中，制備了具有可再加工和回收性的柔性本征高導(dǎo)熱液晶環(huán)氧樹脂（LCER）類玻璃高分子。
2.當(dāng)LCE與E-51的摩爾比為3：1時，LCER的面內(nèi)導(dǎo)熱系數(shù)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(yōu)異的光熱轉(zhuǎn)換功能，且能在808 nm 的近紅外光源下實現(xiàn)可控“開”和“關(guān)”切換、精準(zhǔn)光致驅(qū)動、形狀記憶、局部自修復(fù)和自焊接，并能實現(xiàn)閉環(huán)回收和快速降解。
第一作者：張峰源
郵件地址：[email protected]
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