Hybrid silicone aerogels toward unusual flexibility, functionality, and extended applications
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Here, we overview the developments in the past decade made on organic–inorganic hybrid aerogels and xerogels based on silicone (polyorganosiloxanes) through persistent works by the authors to increase the mechanical strength and flexibility and add functionality. Polymethylsilsesquioxane (PMSQ, CH3SiO3/2) has been found to show unusual strength and flexibility against compression, and their bending properties can also be improved by several strategies. Silicone-based networks with organic bridges between inorganic moieties are also beneficial for these improvements. In particular, organic bridges with a higher fraction and more extended length have been found to allow higher durability against large deformations. In addition, functional groups such as vinyl, chloromethyl, and amino can readily be introduced by starting from organoalkoxysilanes with these functional substituents (e.g., FG−Si(OR)3 or (RO)3Si−FG−Si(OR)3, where FG shows an organic substituent containing functional groups and R is typically methyl or ethyl), and other functional groups such as carboxyl can be introduced by post-gelation modifications on the pre-installed FG in the network. Possibilities in applications such as thermal insulators, photoluminescent media, and photocatalysts are also discussed.
Silicone-based organic–inorganic hybrid aerogels developed by the authors are overviewed.
Improved mechanical flexibility allows ambient pressure drying to yield aerogel-like xerogels.
Reactive organic functional groups can be introduced in the hybrid networks.
KeywordsOrganic–inorganic hybrid Silicone Aerogel Xerogel Mechanical property Functionality
This study has been performed under financial supports from Advanced Low Carbon Technology Research and Development Program (ALCA, Japan Science and Technology Agency) and JSPS KAKENHI Grant Number 17K06015.
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Conflict of interest
The authors declare that they have no conflict of interest.
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