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Han Yan^#, Xiaojun Dai^#, Kunpeng Ruan, Sijie Zhang, Xuetao Shi, Yongqiang Guo, Huaqiang Cai* and Junwei Gu*. Flexible thermally conductive and electrically insulating silicone rubber composite films with BNNS@Al₂O₃ fillers. Advanced Composites and Hybrid Materials, 2021, 4: 36-50. （即時因子6.886）

（https://doi.org/10.1007/s42114-021-00208-1）

AbstractWith the advent of 5G era, the electronic and electrical industries are in increasingly urgent demand for flexible materials with high thermal conductivity coefficients (λ). In this paper, alumina (Al₂O₃) was chemically grafted to the surface of boron nitride nanosheets (BNNS) to prepare hetero-structured thermally conductive fillers (BNNS@Al₂O₃), and two-component room temperature vulcanized silicone rubber (RTV-2SR) was used as the polymer matrix. Then BNNS@Al2O3/RTV-2SR flexible thermally conductive and electrically insulating composite films were prepared by shear-coating. Results of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) showed that the BNNS@Al₂O₃ hetero-structured thermally conductive fillers with ‘point-plane’ structure were successfully prepared. The BNNS@Al₂O₃ hetero-structured thermally conductive fillers successfully achieved the synergy of Al2O3 and BNNS, and had more significant improvement on λ than single Al₂O₃, single BNNS and simply blending BNNS/Al₂O₃. When the amount of BNNS@Al₂O₃ was 30 wt% (BNNS/Al2O3, 1:1, wt:wt), the in-plane λ (λ∥) and through-plane λ (λ⊥) of the BNNS@Al₂O₃/RTV-2SR thermally conductive composite film reached 2.86 W/mK and 0.89 W/mK, 2.8 times λ∥ (1.01 W/mK) and 4.2 times λ⊥ (0.21 W/mK) pure RTV-2SR film, also higher than those of BNNS/RTV-2SR (with single BNNS, λ∥=2.46 W/mK, λ⊥=0.76 W/mK), Al₂O₃/RTV-2SR (with single Al₂O₃, λ∥=1.62 W/mK, λ⊥=0.49 W/mK) and (BNNS/Al₂O₃)/RTV-2SR (with simply blending BNNS/Al₂O₃, 1:1, wt:wt, λ∥=2.04 W/mK, λ⊥=0.62 W/mK) thermally conductive composite films with the same fillers amount. Meanwhile, the prepared BNNS@Al₂O₃/RTV-2SR thermally conductive composite film obtained excellent mechanical properties, electrical insulation properties and thermal properties. Its tensile strength, elongation at break, hardness, dielectric constant (ε), dielectric loss (tanδ), volume resistivity (ρv), glass transition temperature (Tg) and heat resistance index temperature (THRI) respectively reached 0.84 MPa, 175%, 27 HA, 3.89, 0.0088, 5.76×1011 Ω·cm, -40.1^oC and 185.3^oC. This work can provide a new idea for the preparation of hetero-structured thermally conductive fillers and flexible thermally conductive and electrically insulating composite films.

隨著5G時代的到來，電子電氣行業(yè)對于具有高導(dǎo)熱系數(shù)（λ）的柔性導(dǎo)熱材料的需求日益迫切。本文通過化學(xué)接枝法將氧化鋁（Al₂O₃）接枝到氮化硼納米片（BNNS）上，制備了一種具有“點-面”結(jié)構(gòu)的二元異質(zhì)結(jié)構(gòu)導(dǎo)熱填料（Al2O3@BNNS），然后以雙組份室溫硫化硅橡膠（RTV-2SR）為基體，通過剪切涂覆制備了Al2O3@BNNS/RTV-2SR柔性導(dǎo)熱絕緣復(fù)合膜。結(jié)果表明，Al₂O₃@BNNS異質(zhì)結(jié)構(gòu)導(dǎo)熱填料對RTV-2SR導(dǎo)熱復(fù)合膜的導(dǎo)熱性能具有協(xié)同提升效應(yīng)。當Al2O3@BNNS用量為30 wt%（Al2O3:BNNS，1:1，wt:wt）時，Al2O3@BNNS/RTV-2SR導(dǎo)熱復(fù)合膜的面內(nèi)λ（λ∥）和面間λ（λ⊥）分別達到2.86 W/mK和0.89 W/mK，為純RTV-2SR的λ∥（1.01 W/mK）和λ⊥（0.21 W/mK）的2.8倍和4.2倍，且優(yōu)于相同填料用量下的BNNS/RTV-2SR（單一BNNS，λ∥=2.46 W/mK，λ⊥=0.76 W/mK）、Al₂O₃/RTV-2SR（單一Al₂O₃，λ∥=1.62 W/mK，λ⊥=0.49 W/mK）和Al₂O₃/BNNS/RTV-2SR（Al2O3/BNNS簡單共混，1:1，wt:wt，λ∥=2.04 W/mK，λ⊥=0.62 W/mK）導(dǎo)熱復(fù)合膜。并且，本文制備的Al₂O₃@BNNS/RTV-2SR導(dǎo)熱復(fù)合膜兼具良好的力學(xué)性能、絕緣性能和耐熱性能，當Al₂O₃@BNNS用量為30 wt%時，其拉伸強度、斷裂伸長率、硬度、介電常數(shù)（e）、介電損耗（tand ）、體積電阻率（ρv）、玻璃化轉(zhuǎn)變溫度（Tg）和耐熱指數(shù)（THRI）分別達到0.84 MPa、175%、27 HA、3.89、0.0088、5.76×1010 Ω·cm、-44.1^oC和185.3^oC。本工作為異質(zhì)結(jié)構(gòu)導(dǎo)熱填料及柔性導(dǎo)熱絕緣復(fù)合膜的制備研究提供了一種新的思路，在5G電子電氣設(shè)備領(lǐng)域具有潛在的應(yīng)用。