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Relationship between polarity of template hydrogel and nanoporous structure replicated in sol–gel-derived silica matrix

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Abstract

We replicated the nanoscopic network structure of acrylamide series hydrogels in silica matrix. In the replication, the mutual affinity of the template polymeric species to sol–gel-derived silica matrix significantly affects the replicated porous structure formed in the silica matrix. In this work, we intended to fabricate nanoscopic replicas of hydrogels of acrylamides with various hydrophobic end groups. First, the alcoxy silane, tetraethylorthosilicate (TEOS) was hydrolyzed with the template hydrogel. Subsequently, the nanoporous silica solid structure was obtained by removing the hydrogel by calcination in air at 600°C. The nanoscopic structure of those replicas was estimated by transmission electron microscopy (TEM) and nitrogen adsorption/desorption at 77 K. Basically, the nanoscopic replication was possible using the examined hydrogels of polyacrylamides. As the template hydrogel became more nonpolar, the size of the nanopores in the silica replica increased. Thus, the contrast in the polarity between the template hydrogel and silica matrix leads to the enhanced driving force for the mutual segregation or phase separation to occur. The replicated nanoporous structure is considered as a type of a transient structure arrested on the way to the completion of the phase separation of the template polymeric species from the silica matrix. Therefore, the larger contract in the polarity between the structure directing hydrogel and solid matrix lead to the formation of the larger nanopores because of the enhancement in the driving force toward the segregation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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