Xiao Zhong#, Xutong Yang#, Kunpeng Ruan, Junliang Zhang*, Haitian Zhang and Junwei Gu*. Discotic Liquid Crystal Epoxy Resins Integrating Intrinsic High Thermal Conductivity and Intrinsic Flame Retardancy. Macromolecular Rapid Communications, 2022, 43(1): 2100580. 2020IF=5.734

https://doi.org/10.1002/marc.202100580

Abstract

The integration of intrinsic thermal conductivity and intrinsic flame retardancy of epoxy resins shows wider application prospects in electricals and electronics. Discotic liquid crystal epoxy (D-LCE) is synthesized from pyrocatechol, 2-allyloxyethanol and 3-chloroperoxybenzoic acid. P/Si synergistic flame-retardant co-curing agent (DOPO-POSS, DP) is synthesized from p-hydroxybenzaldehyde, 9, 10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) and amino terminated polysilsesquioxane (POSS). Finally, D-LCE is cured within liquid crystal range with 4, 4’-diaminodiphenyl methane (DDM) and DP, to obtain intrinsic highly thermal conductive/flame-retardant epoxy resins (D-LCERDP). D-LCERDP-10.0 (10.0 wt% DP) synchronously possesses excellent intrinsic thermal conductivity and intrinsic flame retardancy, with thermal conductivity coefficient in vertical and parallel direction (λ⊥ and λ∥) of 0.34 W m-1 K-1 and 1.30 W m-1 K-1, much higher than that of general bisphenol A epoxy resin (E-51, λ⊥ of 0.19 W m-1 K-1, λ∥ of 0.65 W m-1 K-1). The limiting oxygen index (LOI) value of D-LCERDP-10.0 reaches 31.1, also better than those of E-51 (19.8) and D-LCER (21.3).

集本征导热及本征阻燃功能为一体的环氧树脂在电子电气领域具有广阔的应用前景。本文以邻苯二酚、乙二醇单烯丙基醚和间氯过氧苯甲酸为主要原料合成的苯并菲类盘状液晶环氧（D-LCE）为基体，4, 4’-二氨基二苯甲烷（DDM）为固化剂，以对羟基苯甲醛、端胺基聚倍半硅氧烷（NH2-POSS）和9, 10-二氢-9-氧杂-10-磷杂菲-10-氧化物（DOPO）为主要原料合成的DOPO-POSS（DP）为共固化剂，浇注成型制备本征型高导热/阻燃液晶环氧树脂（D-LCERDP）。结果表明：当DP的用量为10.0 wt%时，D-LCERDP具有优异的本征导热性能和最优的本征阻燃性能。D-LCERDP-10.0垂直方向和水平方向的导热系数（λ⊥和λ∥）分别为0.34 W/（m·K）和1.30 W/（m·K），远优于E-51的λ⊥（0.19 W/（m·K））和λ∥（0.65 W/（m·K））；其极限氧指数（LOI）提高至31.1，也远优于E-51（19.8）和D-LCER（21.3）。

论文创新点

1. 通过引入盘状液晶结构和P/Si协同阻燃基团，分别合成了苯并菲类盘状液晶环氧（D-LCE）和DOPO-POSS（DP）共固化剂，进而制备得到本征型高导热/阻燃液晶环氧树脂（D-LCERDP）。

2. 当DP的用量为10.0 wt%时，D-LCERDP-10.0垂直方向和水平方向的导热系数（λ⊥和λ∥）分别为0.34 W/（m·K）和1.30 W/（m·K），远优于E-51的λ⊥（0.19 W/（m·K））和λ∥（0.65 W/（m·K））。

3. D-LCERDP-10.0具有优异的本征阻燃性能，其极限氧指数（LOI）为31.1（阻燃等级达到UL-94 V-0级），远优于E-51（19.8）和D-LCER（21.3）。