Key Laboratory of Enhanced Heat Transfer and Energy Conservation, The Ministry of Education, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
Guangdong Engineering Technology Research Center of Efficient Heat Storage and Application, South China University of Technology, Guangzhou 510640, China.
Nanoscale. 2023 Feb 16;15(7):3419-3429. doi: 10.1039/d2nr05587b.
Incorporating phase change capsules into polymeric matrices is an effective approach for developing flexible composites with both heat storage capacity and good thermal reliability, while the interfacial heat conductance between the capsules and the matrix has seldom been considered. Herein, paraffin@SiO nanocapsules synthesized by an interfacial polycondensation process using a basic catalyst were incorporated into a polydimethylsiloxane matrix for the first time to prepare phase change composites at different loadings. Furthermore, the composites containing the nanocapsules were systematically compared with the composites containing the paraffin@SiO microcapsules synthesized using an acidic catalyst. It is shown that, at every identical mass fraction, the composites containing the nanocapsules not only possessed larger latent heat than those containing the microcapsules, but also exhibited higher thermal conductivity and lower hardness. The enhancement in thermal conductivity as well as the decline in hardness for the composite containing the nanocapsules are revealed to originate from a larger amount of hydroxyl groups at the surfaces of the nanocapsules than the microcapsules, which could form more hydrogen bonds with the polymer matrix. This bonding favored the interfacial heat conductance between the nanocapsules and the matrix together with decreasing the crosslinking density of the matrix. Subsequently, composites with enhanced thermal conductivity were developed by combining the nanocapsules with a BN filler. By evaluating the performance for chip heat dissipation, it was found that, when the chip was heated at a power of 10 W, the incorporation of the paraffin@SiO nanocapsules at a loading of 36 wt% into the polymer matrix made a remarkable decrease in the chip equilibrium temperature by 31.7 °C, and a further decline by 8.9 °C occurred when combined with 16 wt% BN. This work sheds light on facilitating the interfacial heat conductance between phase change capsules and the polymer matrix by hydrogen bonding.
将相变胶囊纳入聚合物基体中是开发具有储热能力和良好热可靠性的柔性复合材料的有效方法，而胶囊与基体之间的界面热导率很少被考虑。在此，首次使用碱性催化剂通过界面缩聚工艺合成了石蜡@SiO 纳米胶囊，并将其掺入聚二甲基硅氧烷基体中，以不同的负载制备相变复合材料。此外，系统比较了含有纳米胶囊的复合材料与使用酸性催化剂合成的含有石蜡@SiO 微胶囊的复合材料。结果表明，在相同的质量分数下，含有纳米胶囊的复合材料不仅具有比含有微胶囊的复合材料更大的潜热，而且具有更高的导热系数和更低的硬度。含有纳米胶囊的复合材料的导热系数提高和硬度降低，是由于纳米胶囊表面的羟基数量比微胶囊多，与聚合物基体形成更多氢键的结果。这种键合有利于纳米胶囊与基体之间的界面热导，并降低基体的交联密度。随后，通过将纳米胶囊与 BN 填料结合，开发了具有增强导热性能的复合材料。通过评估芯片散热性能，发现当芯片在 10 W 的功率下加热时，将石蜡@SiO 纳米胶囊以 36wt%的负载量掺入聚合物基体中，可使芯片的平衡温度显著降低 31.7°C，而当与 16wt%的 BN 结合时，又进一步降低了 8.9°C。这项工作为通过氢键促进相变胶囊与聚合物基体之间的界面热导提供了思路。
