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首页> 外文期刊>RSC Advances >Preparation and pyrolysis characteristics of PNIPAM-grafted SiO2 hollow spheres loading vitamin C
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Preparation and pyrolysis characteristics of PNIPAM-grafted SiO2 hollow spheres loading vitamin C

机译：PNIPAM接枝负载维生素C的SiO2空心球的制备及热解特性

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摘要

Thermo-responsive poly(N-isopropyl acrylamide)-grafted SiO2 hollow spheres (PSHS) were successfully prepared by a multi-step reaction, and then they were used to load vitamin C (VC). Pyrolysis characteristics and kinetic and thermodynamic parameters of PSHS loading VC were measured via thermogravimetric analysis (TGA). Two peaks at 193.03 degrees C and 247.56 degrees C were obtained in the DTG curve of PSHS loading VC, which corresponded to the decomposition of the physically absorbed VC and bound VC molecules formed by hydrogen bonding between VC and PSHS respectively. The average value of activation energy calculated by the Coats-Redfern method was 78.91 kJ mol(-1), equal to the activation enthalpy (77.31 kJ mol(-1)). The activation entropy was -82.60 J mol(-1) K-1 and the activation free energy was 115.82 kJ mol(-1). These results proved that VC was encapsulated into PSHS via hydrogen bonding and van der Waals force. Finally, PSHS loading VC exhibited excellent temperature-controllable release property.
机译：通过多步反应成功制备了热响应性聚（N-异丙基丙烯酰胺）接枝的SiO2中空球（PSHS），然后将其用于负载维生素C（VC）。通过热重分析（TGA）测量了PSHS VC的热解特性以及动力学和热力学参数。在PSHS负载VC的DTG曲线中获得了193.03°C和247.56°C的两个峰，分别对应于物理吸收的VC和VC和PSHS之间通过氢键形成的结合VC分子的分解。通过Coats-Redfern方法计算出的活化能平均值为78.91 kJ mol（-1），等于活化焓（77.31 kJ mol（-1））。活化熵为-82.60 J mol（-1）K-1，活化自由能为115.82 kJ mol（-1）。这些结果证明了VC通过氢键和范德华力被封装到PSHS中。最终，PSHS加载VC表现出优异的温度可控释放性能。

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