Thermal stability of POSS/methylsilicone nanocomposites
Thermal stability of POSS/methylsilicone nanocomposites
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DOI：
10.1016/j.compscitech.2007.01.023
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发表时间：
2007-10-01
影响因子：
9.1
通讯作者：
Liu, L.
中科院分区：
文献类型：
--
作者：
Liu, Y. R.;Huang, Y. D.;Liu, L.
采用化学改性的方法制备了三种POSS硅烷醇（三硅醇苯基POSS、三硅醇异丁基POSS和单硅醇异丁基POSS）增强甲基硅油，采用物理共混的方法制备了一种不含羟基的POSS（甲基丙烯酰基POSS）改性甲基硅油的甲基硅油纳米复合材料。采用凝胶渗透色谱（GPC）、傅里叶变换红外光谱（FTIR）和透射电镜（TEM）对杂化材料的结构进行了表征。GPC和FTIR光谱表明三种POSS硅醇与甲基硅树脂成功键合。透射电镜分析表明，POSS硅醇在分子水平上溶解于甲基硅树脂中。然而，甲基丙烯酸-POSS在聚合物树脂体系中存在一定的聚集。采用热重分析（TGA）、固体Si-29 NMR和X射线光电子能谱（XPS）研究了POSS/甲基硅纳米复合材料的热稳定性。所有这些技术都表明，POSS的掺入导致分解温度和热氧化抗力的提高。化学键合的POSS硅烷醇增强的甲基硅纳米复合材料比原始的甲基硅更热稳定，主要是通过Si-OH基团的缩合反应和POSS笼在甲基硅基体中的纳米级分散来减少硅烷醇端基对热稳定性的影响。对于物理混合体系，其热稳定性的提高主要归因于甲基丙烯酸酯-POSS对聚合物基体的纳米增强作用。四种POSS中的硅氧基团与羟基之间存在氢键作用以及无机SiO2保护层的形成也是提高甲基硅热稳定性的重要因素。(c)2007爱思唯尔有限公司版权所有。
Methylsilicone nanocomposites containing polyhedral oligomeric silsesquioxane (POSS) were prepared, including three kinds of POSS silanols (TriSilanolPhenyl-POSS, TriSilanollsobutyl-POSS and MonoSilanollsobutyl-POSS) reinforced methylsilicone through chemical modification method and one kind of non-hydroxyl-containing POSS (Methaeryl-POSS) modified methylsilicone through physical blend. The structures of the obtained hybrid materials were characterized with Gel Permeation Chromatograph (GPC), Fourier transform infrared (FTIR) and transmission electron microscopy (TEM). The GPC and FTIR spectra suggested successful bonding of three kinds POSS silanols and methylsilicone resin. TEM analysis showed that POSS silanols can dissolve in methylsilicone resin at the molecular level. However, there was some aggregation of Methacryl-POSS in the polymer resin systems. Thermal stability of POSS/methylsilicone nanocomposites was investigated by thermogravimetric analysis (TGA), solid-state Si-29 NMR and X-ray photoelectron spectroscopy (XPS). All these techniques showed that POSS incorporation result in increased decomposition temperatures and thermal oxidation resistance. Chemically bonded POSS silanols reinforced methylsilicone nanocomposites are thermally more stable than the original methylsilicone, primarily by reducing the effects of silanol end groups on the thermolysis through condensation reaction of Si-OH groups and the nanoscaled dispersion of POSS cages in methylsilicone matrixes. For the physically mixed system, the enhancement of thermal stability could be mainly ascribed to the nanoreinforcement effect of Methacryl-POSS on the polymer matrix. The formation of protective inorganic SiO2 layer and the hydrogen bonding existed between the hydroxyl group and the siloxane groups of four kinds of POSS are also important factors for the improvement of the thermal stability of methylsilicone. (c) 2007 Elsevier Ltd. All rights reserved.