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

Abstract

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.

Boron Nitride Aerogels with Super‐Flexibility Ranging from Liquid Nitrogen Temperature to 1000 °C

“…As shown in Figure b, six‐cycles compressive strain–stress curves (with increasing strain from 5% to 75%) of the BN aerogel exhibit a continuous trend, demonstrating a perfect shape recovery 6b. Furthermore, 50 cycles of consecutive loading–unloading (Figure c, ε = 40%) exhibited similar features as other superelastic materials, such as graphene foams, CNT aerogels, and silicone aerogels 1f,8. For the recovery process, unrecoverable residual deformations of about ε = 2.8%, ε = 7.6% remained after 10‐ and 50‐cycles at 40% strain, respectively (for more details see Figure S31, Supporting Information) due to the appearance of nanoribbon slippage and fractured junction nodes during the loading–unloading cycles (Figure S28, Supporting Information).…”

“…To overcome the above‐mentioned flaws, many strategies have been developed, such as directional freeze‐casting of the sol precursors, conformal growth of the incipient networks, cross‐linking of aerogels with organic polymers, chemical vapor deposition (CVD) growth within a template, etc. Recently, an improved multidirectional freezing strategy was developed in order to construct multioriented‐microladder arrays in aerogels.…”

“…The resulting aerogel can bear an iterative and multidirectional cutting pressure with a complete recovery of its original shape 7b. In addition, the double‐cross‐linked aerogels exhibited super‐flexibility with excellent toleration of the compressing, bending or twisting stress . However, aerogels with a remarkable mechanical flexibility are still rarely reported, without mentioning whether those could maintain their flexibility over a broader temperature range.…”

Robust Silica-Cellulose Composite Aerogels with a Nanoscale Interpenetrating Network Structure Prepared Using a Streamlined Process

“…Silica aerogels are typical inorganic oxide aerogels that have been widely studied to improve their mechanical properties and streamline the preparation process [17,18]. Two strategies have been explored: the construction of an organic-inorganic hybrid gel skeleton [19,20] and the introduction of reinforcing materials in the gel skeleton to produce a composite aerogel [21,22]. Hybrid gel skeleton construction involves the synthesis of a special precursor with a flexible group or chain segment through an innovative organic reaction, followed by the sol-gel process [23,24].…”

Thermal conductivity of polyvinylpolymethylsiloxane aerogels with high specific surface area

“…These aerogels prepared with polyorganoalkoxysilane precursors obtained by radical polymerization of vinyl monomers exhibit excellent bending and compression exibility. Recently, Zu's group [22][23][24] has rst prepared the doubly cross-linked polyvinylpolymethylsiloxane aerogels (PVPMSAs), which has solved the brittleness of traditional silica aerogels. This strategy can signicantly enhance the skeleton structure of aerogels and prevent aerogels from cracking in the drying process.…”