Kuan Zhang, Junliang Zhang*, Lin Dang, Yuhao Wu, Mukun He, Hua Guo, Xuetao Shi, Hua Qiu and Junwei Gu*. High intrinsic thermal conductivity and low dielectric constant of liquid crystalline epoxy resins with fluorine-containing semi-IPN structures. Science China Chemistry, 2025, 10.1007/s11426-024-2504-y. 2023IF=10.4.（1區(qū)化學(xué)Top期刊，中國(guó)科技期刊卓越行動(dòng)計(jì)劃-領(lǐng)軍類期刊項(xiàng)目）
https://doi.org/10.1007/s11426-024-2504-y
Abstract
High integration, high frequency, high power, and miniaturization of electrical and electronic devices have raised higher demands for epoxy resins with both high intrinsic thermal conductivity and low dielectric properties. Herein, a series of linear fluorinated epoxy copolymers (poly(PFS-co-GMA)) were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly(PFS-co-GMA) was introduced into the cross-linked network of a biphenyl-based liquid crystalline epoxy (LCE) by forming a semi-interpenetrating polymer network (semi-IPN). The prepared liquid crystalline epoxy resins (LCERs) simultaneously exhibited high intrinsic thermal conductivity and low dielectric properties. The molar mass and mass fraction of poly(PFS-co-GMA) were found to have a profound effect on the thermal conductivity and dielectric performance of LCERs. For instance, poly(PFS-co-GMA) with the number average molar mass (Mn) of 4300 and 7800 g/mol showed a decreasing effect on the thermal conductivity (λ) of LCERs whereas the polymer with Mn of 10500 g/mol enhanced the λ. The intrinsic λ of LCERs increased to a remarkable highest value of 0.40 W/(m·K), which was twice that of conventional epoxy resin (0.20 W/(m·K)). In addition, introducing poly(PFS-co-GMA) would significantly decrease the dielectric constant (ε) and dielectric loss tangent (tanδ) of LCERs from 3.44 and 0.035 to 2.49 and 0.001 at 1 MHz, respectively. Notably, the ε and tanδ could remain relatively stable over a wide range of frequencies and temperatures up to 120℃. Additionally, the semi-IPN structure enhanced the hardness, electrical insulation, and hydrophobicity of LCERs.
隨著電子電氣設(shè)備的高集成化、高頻率化、高功率化和微型化，兼具本征高導(dǎo)熱系數(shù)和低介電常數(shù)環(huán)氧樹脂的需求量越來越大。本文通過可逆加成-斷裂鏈轉(zhuǎn)移（RAFT）聚合合成一系列線性含氟環(huán)氧共聚物poly(PFS-co-GMA)，并將其與聯(lián)苯型液晶環(huán)氧單體（LCE）共聚構(gòu)建具有半互穿聚合物網(wǎng)絡(luò)（semi-IPN）結(jié)構(gòu)的液晶環(huán)氧樹脂（LCERs）。聯(lián)苯液晶基元間的相互堆疊、氟原子對(duì)液晶有序結(jié)構(gòu)的促進(jìn)作用以及semi-IPN結(jié)構(gòu)共同促使環(huán)氧樹脂固化網(wǎng)絡(luò)內(nèi)部有序結(jié)構(gòu)的形成，有效抑制聲子散射，降低分子極化率，同步賦予環(huán)氧樹脂本征高導(dǎo)熱系數(shù)（λ）以及低介電常數(shù)（ε）和低介電損耗角正切（tanδ）。研究表明，poly(PFS-co-GMA)的分子量和質(zhì)量分?jǐn)?shù)對(duì)LCERs的導(dǎo)熱性能和介電性能有著顯著影響。當(dāng)poly(PFS-co-GMA)的數(shù)均分子量（Mn）為4300 g/mol和7800 g/mol時(shí)，其使LCERs的本征λ降低；而當(dāng)Mn為10500 g/mol時(shí)，LCERs的本征λ顯著提升，最高可達(dá)0.40 W/(m·K)，是傳統(tǒng)環(huán)氧樹脂（0.20 W/(m·K)）的2倍。此外，引入poly(PFS-co-GMA)會(huì)顯著降低LCERs的ε和tanδ，其在1 MHz下分別從3.44和0.035降至2.49和0.001。同時(shí)，ε和tanδ可以在較寬溫度（20~120℃）范圍內(nèi)保持相對(duì)穩(wěn)定。此外，semi-IPN結(jié)構(gòu)提升了LCERs的硬度、電絕緣性和疏水性。
論文亮點(diǎn)
1. 將含氟線性聚合物poly(PFS-co-GMA)引入到聯(lián)苯型液晶環(huán)氧的固化網(wǎng)絡(luò)中構(gòu)建半互穿聚合物網(wǎng)絡(luò)結(jié)構(gòu)，同步賦予液晶環(huán)氧樹脂（LCERs）本征高導(dǎo)熱系數(shù)和低介電常數(shù)。
2. 當(dāng)poly(PFS-co-GMA)的Mn為10500 g/mol且質(zhì)量分?jǐn)?shù)為15 wt%時(shí)，LCERs具有最高的本征λ以及最低的ε和tanδ，其λ為0.40 W/(m·K)，是E-51（0.20 W/(m·K)）的2倍。
3. LCERs的ε和tanδ分別從E-51的3.44和0.035降低至2.49和0.001（1 MHz），并在較寬溫度（20~120℃）范圍內(nèi)保持相對(duì)穩(wěn)定；LCERs兼具優(yōu)異的硬度、電絕緣性和疏水性。
第一作者：張寬郵件地址：zhangkuan@mail.nwpu.edu.cn
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