Elastic methyltrimethoxysilane based silica aerogels reinforced with polyvinylmethyldimethoxysilane

Abstract

Native silica aerogels are fragile and brittle, which prevents their wider utility. For designing more durable and stronger silica aerogels, polyvinylmethyldimethoxysilane (PVMDMS) polymers as effective and multifunctional reinforcing agents were used to strengthen methyltrimethoxysilane based silica aerogels (MSAs). The PVMDMS polymer, which was composed of long-chain aliphatic hydrocarbons and organic side-chain methyl and alkoxysilane groups, was integrated into silica networks via a simple sol-gel process. Compared with MSAs, PVMDMS reinforced MSAs (PRMSAs) display many fascinating characteristics. PRMSAs exhibit improved hydrophobic properties (water contact angle of 136.9 ) due to abundant methyl groups in the silica networks. Benefiting from the fine integration of PVMDMS polymers into MSAs, PRMSAs show a perfectly elastic recovery property, the compressive strength of which ranges from 0.19 to 1.98 MPa. More importantly, PVMDMS polymers have successfully suppressed the growth of secondary particles. Homogeneous silica networks formed by nanoscale particles give PRMSAs a high surface area of 1039 m 2 g À1 . Moreover, optimized PRMSAs also exhibit a low thermal conductivity of 0.0228 W m À1 K À1 under ambient conditions, and their thermal stability reaches up to 222.3 C in air. All the results obtained from this paper will help us to design silica aerogels.

Versatile Thermal‐Solidifying Direct‐Write Assembly towards Heat‐Resistant 3D‐Printed Ceramic Aerogels for Thermal Insulation

“…These results are consistent with the observation from the Fourier transform infrared (FTIR) spectra (Figure S7, Supporting Information). The absorption peaks near 1120 cm -1 and 790 cm -1 are ascribed to the stretching vibrations of Si−O bonds, [33] and the broad absorption peaks at around 3440 cm -1 and 1640 cm -1 correspond to −OH groups. [32,33] In the FTIR spectrum of PTS aerogels, the vibration absorption peaks of Ti-O bands appear at around ≈600 cm -1 .…”

“…The absorption peaks near 1120 cm -1 and 790 cm -1 are ascribed to the stretching vibrations of Si−O bonds, [33] and the broad absorption peaks at around 3440 cm -1 and 1640 cm -1 correspond to −OH groups. [32,33] In the FTIR spectrum of PTS aerogels, the vibration absorption peaks of Ti-O bands appear at around ≈600 cm -1 . [34] For PAS aerogels, the two strong and well-resolved absorption peaks at 3090 cm -1 and 3300 cm -1 are assigned to boehmite −OH groups, [35] which means that boehmite possesses a well crystalline structure.…”

Silica-Based Aerogels with Tunable Properties: The Highly Efficient BF3-Catalyzed Preparation and Look inside Their Structure

“…Also, SAs obtained from methyl-, ethyl-, and vinyltrimethoxysilane, alkoxysilyl-substituted polyethylenes and polypropylenes (obtained from Vin–Si­(OR) (3– x ) Me x , allyl–Si­(OR) (3– x ) Me x , for 1 or more days) are known, including filled SAs with high mechanical strength and hydrophobicity in combination with high transparency. This type of SAs will probably take a special place among the most well-known types of materials in the future that will find applications in various fields of science and technology. − …”

“…The stages of gel formation, aging, and preparation ((1), (2), and (3)) are usually very time consuming, from a few days to weeks. As a rule, gel formation (from a few hours to a few days) and subsequent aging (one or more days) are carried out under acid and/or base catalysis (sequential/“independent″) conditions in solvents such as water, methanol, ethanol, and so on. − To form a gel from alkoxysilanes that are the most popular precursors, it is necessary that the rate of the stage of the Si–OR group hydrolysis be higher than the rate of the subsequent stage of condensation to give Si–O–Si groups (polysiloxane system) (Figure ).…”

Elastic Aerogel with Tunable Wettability for Self-Cleaning Electronic Skin

“…Therefore, it is difficult to balance the degree of strong crosslinks and flexible chain to target an elastic aerogel. Researchers have taken many efforts to achieve the elastic performance of organic aerogels. ,− Nanofibers and bacterial cellulose , were introduced into the organic aerogels to enhance the elasticity and robustness of the aerogels . Most of the above mentioned aerogels were fabricated from the consideration of an engineering strategy, while there were few reports on the preparation of elastic aerogels from the viewpoint of molecular design.…”