Thermal Insulating Property of Silsesquioxane Hybrid Film Induced by Intramolecular Void Spaces
Thermal Insulating Property of Silsesquioxane Hybrid Film Induced by Intramolecular Void Spaces
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DOI：
10.1021/acsapm.1c00344
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发表时间：
2021-06
期刊：
影响因子：
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通讯作者：
T. Hamada;Yuki Nakanishi;K. Okada;Satoru Tsukada;A. Uedono;J. Ohshita
中科院分区：
文献类型：
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作者：
T. Hamada;Yuki Nakanishi;K. Okada;Satoru Tsukada;A. Uedono;J. Ohshita
在应用于隔热材料的有机/无机杂化聚合物领域中，乙烯桥接聚硅氧烷薄膜由于其框架中存在分子内空隙而具有增强的隔热性能，是很有前途的材料。为了提高分子内空穴中的含量，进一步提高所得材料的热性能，本文描述了氢二甲基硅化低甲基硅氧烷（MSQ-SiH）与辛烷基多面体低聚硅氧烷（Vinyl-POSS）的硅氢化反应，制备出具有分子内空穴的杂化膜，由于形成共价SiCCSi键，该杂化膜无色透明。作为对照实验，制备了一种聚甲基硅氧烷（MSQ）薄膜和一种含有5 wt %乙烯基poss（复合膜-5）的MSQ薄膜。混合膜5（由MSQ- sih和5 wt %的乙烯基poss制备）的密度和热扩散率（1.19 g/cm3和1.21 × 10-7m2 /s）低于MSQ膜（1.34 g/cm3和1.36 × 10-7m2 /s）和复合膜5 （1.37 g/cm3和1.58 × 10-7m2 /s）。杂化膜-5的失重温度为5% (Td5)，失重温度为10% (Td10)，分别为382℃和453℃，低于MSQ膜（Td5为436℃，Td10为481℃），高于复合膜-5 （Td5为325℃，Td10为453℃）。正电子湮没寿命技术表明，由正电子寿命分量值估计的空穴体积在杂化膜-5 > MSQ膜- >复合膜-5量级减小。综上所述，结果表明聚硅氧烷膜的隔热性能是通过在POSS分子周围形成分子内空隙而得到改善的。
In the field of organic/inorganic hybrid polymers with the application as thermal insulating materials, ethylene-bridged polysilsesquioxane films are promising materials with enhanced thermal insulating properties due to the presence of intramolecular void spaces in their frameworks. With the aim of increasing the content in intramolecular void spaces to further enhance the thermal property of the resulting material, this paper describes the hydrosilylation reaction of hydrodimethyl-silylated oligomethylsilsesquioxane (MSQ-SiH) and octavinyl polyhedral oligomeric silsesquioxane (Vinyl-POSS) to produce a hybrid film with intramolecular void spaces, which was colorless and transparent due to the formation of covalent SiCCSi bonds. As a control experiment, a polymethylsilsesquixane (MSQ) film and an MSQ film containing 5 wt % of Vinyl-POSS (composite film-5) were prepared. Hybrid film-5 (prepared from MSQ-SiH and 5 wt % of Vinyl-POSS) exhibited lower density and thermal diffusivity (1.19 g/cm3and 1.21 × 10–7m2/s) than the MSQ film (1.34 g/cm3and 1.36 × 10–7m2/s) and composite film-5 (1.37 g/cm3and 1.58 × 10–7m2/s). Hybrid film-5 showed a 5% weight loss temperature (Td5) and a 10% weight loss temperature (Td10) of 382 and 453 °C, respectively, which were lower than those of the MSQ film (Td5of 436 °C andTd10of 481 °C) and higher than those of composite film-5 (Td5of 325 °C andTd10of 453 °C). Positron annihilation lifetime technique revealed that the hole volumes estimated from the value of the positronium lifetime component decreased in the order hybrid film-5 > MSQ film > composite film-5. Taken together, the results demonstrate that the thermal insulating property of the polysilsesquioxane film was improved by the formation of intramolecular void spaces around the POSS molecules.