Transparent, Superflexible Doubly Cross-Linked Polyvinylpolymethylsiloxane Aerogel Superinsulators via Ambient Pressure Drying

Abstract

Aerogels have many attractive properties but are usually costly and mechanically brittle, which always limit their practical applications. While many efforts have been made to reinforce the aerogels, most of the reinforcement efforts sacrifice the transparency or superinsulating properties. Here we report superflexible polyvinylpolymethylsiloxane, (CHCH(Si(CH)O)), aerogels that are facilely prepared from a single precursor vinylmethyldimethoxysilane or vinylmethyldiethoxysilane without organic cross-linkers. The method is based on consecutive processes involving radical polymerization and hydrolytic polycondensation, followed by ultralow-cost, highly scalable, ambient-pressure drying directly from alcohol as a drying medium without any modification or additional solvent exchange. The resulting aerogels and xerogels show a homogeneous, tunable, highly porous, doubly cross-linked nanostructure with the elastic polymethylsiloxane network cross-linked with flexible hydrocarbon chains. An outstanding combination of ultralow cost, high scalability, uniform pore size, high surface area, high transparency, high hydrophobicity, excellent machinability, superflexibility in compression, superflexibility in bending, and superinsulating properties has been achieved in a single aerogel or xerogel. This study represents a significant progress of porous materials and makes the practical applications of transparent flexible aerogel-based superinsulators realistic.

Superflexible Multifunctional Polyvinylpolydimethylsiloxane‐Based Aerogels as Efficient Absorbents, Thermal Superinsulators, and Strain Sensors

“…Moreover,a no rganic-inorganic double-cross-linking approach has been found to prepare transparent polyvinylpolymethylsiloxane (PVPMS), polyallypolymethylsiloxane (PAPMS), polyvinylpolysilsesquioxane (PVPSQ), and polyallypolysilsesquioxane (PAPSQ) aerogels with high flexibility, processability,a nd excellent thermal insulation properties. [39,40] Herein, we report unprecedented doubly cross-linked aerogels based on polyvinylpolydimethylsiloxane (PVPDMS) with excellent mechanical properties,s uch as superflexiblity and processability and multifunctionality combining thermal insulation, selective absorption, and strain sensing properties via the double-cross-linking strategy consisting of free-radical polymerization/hydrolytic polycondensation without any additional organic cross-linkers.F ree radical polymerization of asingle precursor vinyldimethylmethoxysilane (VDMMS) or co-polymerization of precursors VDMMS and vinylmethyldimethoxysilane (VMDMS) in the presence of ar adical Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.…”

“…Moreover,a no rganic-inorganic double-cross-linking approach has been found to prepare transparent polyvinylpolymethylsiloxane (PVPMS), polyallypolymethylsiloxane (PAPMS), polyvinylpolysilsesquioxane (PVPSQ), and polyallypolysilsesquioxane (PAPSQ) aerogels with high flexibility, processability,a nd excellent thermal insulation properties. [39,40] Herein, we report unprecedented doubly cross-linked aerogels based on polyvinylpolydimethylsiloxane (PVPDMS) with excellent mechanical properties,s uch as superflexiblity and processability and multifunctionality combining thermal insulation, selective absorption, and strain sensing properties via the double-cross-linking strategy consisting of free-radical polymerization/hydrolytic polycondensation without any additional organic cross-linkers.F ree radical polymerization of asingle precursor vinyldimethylmethoxysilane (VDMMS) or co-polymerization of precursors VDMMS and vinylmethyldimethoxysilane (VMDMS) in the presence of ar adical initiator (di-tert-butyl peroxide,DTBP) is followed by hydrolytic polycondensation of the obtained polymers with astrong base catalyst (tetramethylammonium hydroxide,T MAOH) to give ad oubly cross-linked porous structure consisting of flexible polydimethylsiloxanes (/polymethylsiloxanes) and hydrocarbon chains.A erogels based on the PVPDMS network and PVPDMS/polyvinylpolymethylsiloxane (PVPMS) copolymer network are then obtained via low-cost APD or FD.H ighly flexible and conductive PVPDMS/PVPMS/graphene nanocomposite aerogels with astrain sensing property have also been prepared by ahomogeneous incorporation of graphene nanoplatelets in the hydrolytic polycondensation process.S ynthetic approaches toward an excellent combination of these functionalities in as ingle material system are discussed from the viewpoint of structure-,property relationship.…”

Versatile Aerogels for Sensors

“…The obtained cellulose aerogel shows high mechanical properties, good biocompatibility, and can be used as an excellent supporting material in many fields . Besides, there are other organic aerogels reported in the literature, such as chitosan, cyclodextrin, polyurethane, PVA, polypyrrole(PPy), polyvinylpolymethylsiloxane, nanofibrous Kevlar, poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS), and so on. The properties of organic aerogels can be easily controlled by adjusting the type of the monomer and the combination of different monomers.…”

Superhydrophobic polyimide aerogels via conformal coating strategy with excellent underwater performances

“…Over the past years, most of the research works focused on the silica and metal‐oxide aerogels . Recently, a variety of new aerogels have been synthesized, such as organic polymer‐based aerogels, supramolecular aerogels, hybrid aerogels, and graphene aerogels . Organic polymer‐based aerogels including polyaimide, polyurethane, and cellulose aerogels have attracted increasing interests due to their outstanding mechanical properties.…”