Influence of gamma irradiation on the hydrophobicity properties of modified poly(vinyl) alcohol (PVA) aerogels

Polyvinyl alcohol (PVA) aerogels and hydrogels are promising superhydrophilic and superhydrophobic materials. However, the chemical crosslinkers typically used in their synthesis are hazardous and toxic. To address this issue, we developed a sustainable fabrication method for silane-modified, hydrophobic PVA aerogels. This method involves γ-irradiation of PVA for polymerization, followed by silanization through the chemical vapor deposition of methyltrichlorosilane onto the polymer surfaces. Fourier-transform infrared spectral peaks at 1636, 1407, and 1090–1021 cm⁻¹ confirmed polymerization due to γ-irradiation, while peaks at 1270 and 767 cm⁻¹ confirmed silanization. The water contact angles of the aerogels, ranging from 118° to 142°, demonstrated their hydrophobicity. The surface morphologies of the aerogels were analyzed using field-emission scanning electron microscopy and infinite focus microscopy. PVA aerogels treated with a γ-irradiation dosage of 30 kGy were confirmed to be optimal, as they exhibited a water contact angle of 139.0 ± 3.0° and a reduction in surface area after oil treatment. Thermogravimetric analysis and differential scanning calorimetry were used to assess weight-loss behavior, decomposition percentages, and glass transition temperatures of the aerogels. The 30 kGy PVA aerogel showed the highest thermal stability, with a maximum decomposition temperature of 185 °C. The findings confirm that γ-irradiation is a promising, sustainable approach to polymerization, and these silane-modified PVA aerogels show potential for applications in oil-water separation and treatment.