• 文献标题:   Insights into in-situ sol-gel conversion in graphene modified polymer-based silica gels for multifunctional aerogels
  • 文献类型:   Article
  • 作  者:   KARAMIKAMKAR S, BEHZADFAR E, NAGUIB HE, PARK CB
  • 作者关键词:   spinodal decomposition, graphene, solgel chemistry, surface area, bimodal mesoporou, fractal dimension
  • 出版物名称:   CHEMICAL ENGINEERING JOURNAL
  • ISSN:   1385-8947 EI 1873-3212
  • 通讯作者地址:   Univ Toronto
  • 被引频次:   7
  • DOI:   10.1016/j.cej.2019.123813
  • 出版年:   2020

▎ 摘  要

Graphene-modified polymer-based silica aerogels (G-PSAs) are an emerging class of multifunctional material, receiving a lot of attention for a wide range of applications such as sensors, drug-delivery, and tissue-engineering. The bimodal mesoporous structure of G-PSAs is dictated during the gelation process, and it can be tailored by optimizing material and processing parameters. In this study, the main focus is to investigate the mechanism for the formation of the structure that furnished the aerogels with unique pore structures and superb mechanical properties. The dynamic structures along the fabrication process were assessed using advanced techniques such as rheometry, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS) and pore-structure-analyzer. DLS and SAXS results support the notion that the gelation of polyvinyltrimethoxysilane (P-VTMS) yields a nonparticulate structure. A chemically induced spinodal decomposition phase separation was found to explain the collected data. The mass fractal dimension was found to be 1.8, confirming that the percolation theory cannot be used to describe the gelation of both neat P-VTMS and Graphene-modified P-VTMS. The findings showed that, while adding GO to the formulation does not change the stoichiometric ratio of the gelation reaction, it creates spatial hindrance that interferes with the reaction process, delaying the gelation process. Conversely, GnP provides a platform for the reaction that promotes the gelation process. However, GO and GnP shows similar effects on bimodal mesoporous structure of aerogels although provides dramatically different surface areas. This dramatic difference roots in the open pore structure induced by GnP in P-VTMS aerogels. The strategy of nanoplatelets exfoliation during the sol-gel transition by controlling pH opens a new avenue for producing G-PSAs with an exceptionally high surface area (up to similar to 2100 m(2).g(-1)).