The experimental work on the self-cleaned zirconia coatings prepared using a co-precursor sol-gel method is presented here. The zirconia coatings were synthesised using zirconium n-propoxide (ZrPro) precursor and different organosilanes such as trimethyl cholorosilane (TMCS), hexamethyl disilzane (HMDZ) and perfluorodecyl triethoxy silane (FDTES) as coprecursors. The organosilanes have a profound impact in modifying the surfaces making them water repellent. Therefore, the influences of various organosilane co-precursors on the chemical structure, thermal stability, hydrophobicity and roughness of the zirconia coatings were studied by varying the ZrPro:Co-precursor molar ratios. FTIR spectra of zirconia coatings revealed the high intensity of peaks related to C-H, Si-C and Zr-O-Si chemical bonds manifesting their hydrophobic characteristics. The TMCS and HMDZ co-precursorsbased hydrophobic zirconia coatings retained their hydrophobicity up to a temperature of 300 °C as confirmed from TG-DSC analyses. The maximum contact angle of 154°and roughness of nearly 0.316 μm were measured for zirconia coatings prepared using the ZrPro:TMCS molar ratio of 0.3. These superhydrophobic zirconia coatings can be applied for the self-cleaning purpose.
Silica aerogels and their derivatives have outstanding thermal properties with exceptional values in the thermal insulation industry. However, their brittle nature restricts their large-scale commercialization. Thus, enhancing their mechanical strength without affecting their thermal insulating properties is essential. Therefore, for the first time, highly thermally stable poly(acrylamide-co-acrylic acid) partial sodium salt is used as a reinforcing polymer to synthesize hybrid P(AAm-CO-AAc)-silica aerogels via epoxy ring-opening polymerization in the present study. Functional groups in P(AAm-CO-AAc) partial sodium salts, such as CONH2 and COOH, acted as nucleophiles for the epoxy ring-opening reaction with (3-glycidyloxypropyl)trimethoxysilane, which resulted in a seven-fold enhancement in mechanical strength compared to that of pristine silica aerogel while maintaining thermal conductivity at less than 30.6 mW/mK and porosity of more than 93.68%. Moreover, the hybrid P(AAm-CO-AAc)-silica aerogel demonstrated improved thermal stability up to 343 °C, owing to the synergetic effect between the P(AAm-CO-AAc) and the silica aerogel, corresponding to the thermal stability and strong covalent bonding among them. These excellent results illustrate that this new synthetic approach for producing hybrid P(AAm-CO-AAc)-silica aerogels is useful for enhancing the mechanical strength of pristine silica aerogel without impairing its thermal insulating property and shows potential as an industrial heat insulation material.
Silica aerogels and their derivatives have outstanding thermal properties with exceptional values in the thermal insulation industry. However, the brittle nature restricts its large-scale commercialization. Thus, enhancing their mechanical strength without affecting their thermal insulating properties is essential. Therefore, for the first time, highly thermally stable Poly(acrylamide-Co-acrylic acid) partial sodium salt is used as a reinforcing polymer to synthesize hybrid P(AAm-CO-AAc)-silica aerogels via epoxy ring-opening polymerization in the present study. Functional groups in P(AAm-CO-AAc) partial sodium salts, such as CONH2 and COOH, acted as nucleophiles for the epoxy ring-opening reaction with (3-glycidyloxypropyl)trimethoxysilane, which resulted in a seven-fold enhancement in mechanical strength compared to that of a pristine silica aerogel while maintaining the thermal conductivity at less than 30.6 mW/mK and porosity of more than 93.68%. Moreover, the hybrid P(AAm-CO-AAc)-silica aerogel demonstrated improved thermal stability up to 343 ⁰C owing to the synergetic effect between P(AAm-CO-AAc) and the silica aerogel, corresponding to thermal stability and strong covalent bonding among them. These excellent results illustrate that this new synthetic approach for producing hybrid P(AAm-CO-AAc)-silica aerogels is useful for enhancing the mechanical strength of a pristine silica aerogel without impairing its thermal insulating property and shows potential as an industrial heat insulation material.
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