Facile synthesis of ternary flexible silica aerogels with coarsened skeleton for oil–water separation

Silver Nanowires and Silanes in Hybrid Functionalization of Aramid Fabrics

New functionalization methods of meta- and para-aramid fabrics with silver nanowires (AgNWs) and two silanes (3-aminopropyltriethoxysilane (APTES)) and diethoxydimethylsilane (DEDMS) were developed: a one-step method (mixture) with AgNWs dispersed in the silane mixture and a two-step method (layer-by-layer) in which the silanes mixture was applied to the previously deposited AgNWs layer. The fabrics were pre-treated in a low-pressure air radio frequency (RF) plasma and subsequently coated with polydopamine. The modified fabrics acquired hydrophobic properties (contact angle Θ_W of 112-125°). The surface free energy for both modified fabrics was approximately 29 mJ/m², while for reference, meta- and para-aramid fabrics have a free energy of 53 mJ/m² and 40 mJ/m², respectively. The electrical surface resistance (R_s) was on the order of 10² Ω and 10⁴ Ω for the two-step and one-step method, respectively. The electrical volume resistance (R_v) for both modified fabrics was on the order of 10² Ω. After UV irradiation, the Rs did not change for the two-step method, and for the one-step method, it increased to the order of 10¹⁰ Ω. The specific strength values were higher by 71% and 63% for the meta-aramid fabric and by 102% and 110% for the para-aramid fabric for the two-step and one-step method, respectively, compared to the unmodified fabrics after UV radiation.

Polysiloxane Bonded Silica Aerogel with Enhanced Thermal Insulation and Strength

In order to improve the mechanical properties of SiO2 aerogels, PHMS/VTES-SiO2 composite aerogels (P/V-SiO2) were prepared. Using vinyltriethoxysilane (VTES) as a coupling agent, the PHMS/VTES complex was prepared by conducting an addition reaction with polyhydromethylsiloxane (PHMS) and VTES and then reacting it with inorganic silica sol to prepare the organic-inorganic composite aerogels. The PHMS/VTES complex forms a coating structure on the aerogel particles, enhancing the network structure of the composite aerogels. The composite aerogels can maintain the high specific surface area and excellent thermal insulation properties, and they have better mechanical properties. We studied the reaction mechanism during preparation and discussed the effects of the organic components on the structure and properties of the composite aerogels. The composite aerogels we prepared have a thermal conductivity of 0.03773 W·m-1·K-1 at room temperature and a compressive strength of 1.87 MPa. The compressive strength is several times greater than that of inorganic SiO2 aerogels. The organic-inorganic composite aerogels have excellent comprehensive properties, which helps to expand the application fields of silicon-based aerogels.