[Macromolecules] Liquid Crystalline Polyimide Films with High Intrinsic Thermal Conductivities and Robust Toughness
writer：Kunpeng Ruan, Yongqiang Guo and Junwei Gu*
keywords：Thermally conductive composites
source：期刊
specific source：Macromolecules
Issue time：2021年
Low intrinsic thermal conductivity coefficients (λ) of polyimide (PI) films limit their application in heat-prone flexible electronics. By optimizing liquid crystal range to fit curing temperature, a novel kind of intrinsically highly thermally conductive liquid crystalline PI (LC-PI) films are fabricated. When the molar ratio of 4, 4''-diaminodiphenyl ether (ODA) to 1, 4-bis(4-aminophenoxy)benzene (TPE-Q) is 1:3 (sample No. IV), liquid crystal range of preLC-PIIV films is 272~388oC, including curing temperature of 350oC. The LC-PIIV films cured in liquid crystal range retain liquid crystal texture to room temperature, and the in-plane λ (λ∥) and through-plane λ (λ⊥) at room temperature reach 2.11 W/(m·K) and 0.32 W/(m·K), respectively, significantly higher than λ∥ (0.77 W/(m·K)) and λ⊥ (0.15 W/(m·K)) of LC-PII films which are cured out of liquid crystal range. Meanwhile, LC-PIIV films possess excellent mechanical and thermal properties, showing application prospects in high-heating flexible electronics.
聚酰亞胺（PI）膜較低的本征導(dǎo)熱系數(shù)（λ）限制了其在易發(fā)熱柔性電子器件的進(jìn)一步應(yīng)用。通過優(yōu)化調(diào)控液晶區(qū)間與固化溫度相匹配，制備出一種本征高導(dǎo)熱液晶聚酰亞胺（LC-PI）膜。結(jié)果表明，當(dāng)4, 4’-二氨基二苯醚（ODA）和1, 4-雙（4-氨基苯氧基）苯（TPE-Q）的摩爾比為1：3時(shí)（IV號(hào)樣品），preLC-PIIV膜的液晶區(qū)間為272~388oC（包含其固化溫度350oC）；液晶區(qū)間內(nèi)固化的LC-PIIV膜在室溫下保留液晶織構(gòu)，室溫下的面內(nèi)λ（λ∥）與面間λ（λ⊥）分別達(dá)到2.11 W/(m·K)和0.32 W/(m·K)，明顯高于液晶區(qū)間外固化的LC-PII膜的λ∥（0.77 W/(m·K)）與λ⊥（0.15 W/(m·K)）。同時(shí)LC-PIIV膜具有優(yōu)異的力學(xué)性能和熱性能，展現(xiàn)出在高發(fā)熱量柔性電子領(lǐng)域中的應(yīng)用前景。