By Josh Perry, Editor
Researchers from Kyoto University (Japan) have demonstrated a new class of highly-elastic aerogels that avoid the typical brittleness of these materials and can be produced at lower cost than comparable materials.
A new aerogel has demonstrated elasticity and thermal insulation properties. (Wiley)
According to a report from Wiley, the key to the new material’s elasticity and other enhanced properties is a doubly cross-linked organic-inorganic network structure and adjustable network density.
Researchers used monomers vinyldimethylmethoxysilane and vinylmethyldimethoxysilane that are linked into polymer chains using the double bonds in the vinyl group. The polymer chains included side chains (silanes), which are also cross-linked through their methoxy groups (-OCH3).
“The density of the resulting cross-linking of the polymers (polyvinylpolydimethylsiloxane-polyvinylpolymethylsiloxane copolymers) depends on the ratio in which the two monomers were mixed,” the article explained. “Subsequent inexpensive air pressure or freeze drying then forms aerogels with tailored porosity.”
The flexible siloxane and hydrocarbon chains give the aerogel its elasticity. More densely crosslinked versions also have high thermal insulation.
“Also of interest is the selective absorption of the aerogels: exposed to a mixture of hexane and water, they exclusively absorb the hexane, which can subsequently be removed by squeezing the material like a sponge or by evaporation,” the article continued. “This process can then be repeated until the mixture is fully separated. This allows solvents or oils like acetone, toluene, mineral oil, and kerosene to be separated if they accidentally enter a body of water, for example.”
Graphene nanoplatelets were also added to enhance electrical conductivity and showed potential applications as touchpads for electronics or wearables.
The research was recently published in Angewandte Chemie. The abstract read:
“Aerogels are porous materials but show poor mechanical properties and limited functionality, which significantly restrict their practical applications. Preparation of highly bendable and processable aerogels with multifunctionality remains a challenge.
“Herein we report unprecedented superflexible aerogels based on polyvinylpolydimethylsiloxane (PVPDMS) networks, PVPDMS/polyvinylpolymethylsiloxane (PVPMS) copolymer networks, and PVPDMS/PVPMS/graphene nanocomposites by a facile radical polymerization/hydrolytic polycondensation strategy and ambient pressure drying or freeze drying.
“The aerogels have a doubly cross?linked organic–inorganic network structure consisting of flexible polydimethylsiloxanes and hydrocarbon chains with tunable cross?linking density, tunable pore size and bulk density.
“They have a high hydrophobicity and superflexibility and combine selective absorption, efficient separation of oil and water, thermal superinsulation, and strain sensing.”