关键词: 表面改性, 聚二甲基硅氧烷(PDMS), 聚多巴胺(PDA), 导热绝缘, 热管理

Abstract: With the continuous improvement of people's living standards, people have put forward more diverse requirements for the performance of clothing, and it has shown great market prospects. As the future development trend of wearable devices, the heat dissipation of electronic devices has gradually become the key to research and application in various fields, especially in the textile field. If there is no effective heat dissipation, overheating will seriously reduce the performance and reliability of the equipment. Polymers are often used in thermal management materials for their advantages of good processability, high relative molecular mass, low water absorption, high resistivity, high breakdown voltage, corrosion resistance and low cost. However, the inherent low thermal conductivity (0.2~0.5 W/(m·K)) of the polymer matrix generally limits its thermal applications. Usually, thermally conductive fillers such as the inorganic ceramic fillers of aluminum oxide (Al2O3), aluminum nitride(AlN), and zinc oxide(ZnO) are added to the polymer matrix to improve the thermal conductivity of polymers. The addition of these high-density ceramic fillers usually results in low compatibility with the polymer, poor dispersion, high loading, and unsatisfactory improvement of the thermal conductivity of the composites.
To solve the heat dissipation problem in wearable electronic devices, flexible thermal management materials with high thermal conductivity and electrical insulation properties were obtained. Boron nitride (BN) and graphene nanoparticles (GNPs) were selected as hybridized thermally conductive fillers, and B-PDA-G/PDMS flexible thermally conductive and insulating films with different filler contents were prepared by hot-pressing method after surface modification of the hybridized fillers by polydopamine (PDA) and mixing with polydimethylsiloxane (PDMS) matrix. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to investigate the effects of filler B-PDA-G and single BN on improving the thermal conductivity of PDMS membrane materials and to assess the feasibility of their application in the textile field. The results show that the B-PDA-G/PDMS composite membranes can maintain good mechanical properties, electrical insulation and thermal conductivity at low filler filling. When the mass ratio of BN to GNPs is 5:5 and the mass fraction of filler is 30%, the in-plane thermal conductivity of B-PDA-G/PDMS can reach up to 7.63 W/(m-K), which is 2.8 times and 27.3 times higher compared to BN/PDMS materials and pure PDMS materials, respectively. 
By coating the flexible thermally conductive and insulating composites into the electrothermal fabric as the encapsulation coating, it is found that B-PDA-G/PDMS has better heat transfer and dissipation ability compared with BN/PDMS at the safe heating temperature of human body, which demonstrates its broad application prospect in smart wearable products.

Key words: surface modification, polydimethylsiloxane (PDMS), polydopamine (PDA), thermal conductivity and insulation, thermal management