Chemically cross-linked aerogels based on cellulose nanocrystals and polysilsesquioxane
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In this work, we report one-pot synthesis of free standing and porous hybrid cross-linked aerogels based on cellulose nanocrystals (CNCs) and polysilsesquioxane (PSS). The synthesis of the aerogel was carried out in two steps. The first was CNC surface modification, using a 3-isocyanatopropyltriethoxysilane, and the second, a sol–gel process, resulting in the formation of a PSS network which cross-linked with the nanoparticles. 29Si solid state NMR analysis revealed that this network was mostly made up of linear and three-dimensional PSS domains. Aerogels showed shape stability and high porosity (> 89%). The presence of macro and mesopores was confirmed by SEM and BET analyses, respectively, and the presence of the PSS network domains in the pore walls was characterized by TEM. In addition, these CNC/PSS aerogels were omniphilic, absorbing approximately the same amount of both water and toluene. These characteristics make these aerogels interesting material to be used as absorbents for a wide variety of spills.
KeywordsCellulose nanocrystals Polysilsesquioxane Aerogels Silane Sol–gel process
This research was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Grants 2010/17804-7 and 2016/02414-5), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, Grant 136786/2015-4) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes-PNPD, L. C. Battirola fellowship). The authors also gratefully acknowledge the National Institute for Complex Functional Materials (Inomat/INCT), the Brazilian Nanotechnology National Laboratory (LME/LNNano) and staff for the use of TEM facilities, MSc Laura C. E. da Silva and PhD Douglas S. da Silva for TEM measurements. The authors particularly thank Prof. Maria Isabel Felisberti for her assistance in compression tests and data analysis.
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