The science of materials has made significant advancements in the last century, greatly improving and facilitating human life with its discoveries of new and better materials. In the context of sustainability, alternatives are being sought to reduce the environmental impact in the production of these materials. Special emphasis is being placed on reversible interactions, adding dynamism to otherwise static supramolecular systems. In addition to their self-healing capabilities, reversible interactions have demonstrated functional value in terms of responses to stimuli, increased hardness, shape memory, and changes in wetting properties. Due to their ability to alter wetting properties when treated with the appropriate acid, amino-functionalized surfaces hold great promise in sustainability, coating development, biomaterials, corrosion inhibition, and oil-water separation. A lot of research has been conducted in the optimization of the aminosilanization process, which establishes an amine platform and serves as a key step in obtaining the desired reversible interactions. As part of this work, we investigated the impact of glass hydroxylation with a piranha solution and drying on the binding of 3-aminopropyltrimethoxysilane (APTMS) to the glass substrate. The aminofunctionalization of the glass was carried out using a vapor deposition method in a Teflon reactor at elevated temperatures. The number of amine groups on the glass surface was determined by binding 2,4,6-trinitrophenol to the amine groups, washing it off the glass with the addition of K2CO3 base, and spectrophotometrically quantifying the released 2,4,6-trinitrophenol. For the optimization of the aminosilanization process, we examined the effect of reaction temperature and the impact of drying time, which indicated an increase in the number of useful amines with drying time. In the analysis of acid interactions with aminated glass, we focused on changes in the wetting properties of the glass after acid treatment. We used 5 different acids, 3 organic (perfluorooctanoic acid (PFOA), acetic acid, and citric acid) and 2 mineral acids (HCl, H2SO4). Reversibility and repeatability of interactions between aminosilanized glass and acid were observed, as well as changes in the contact angle after treatment with the respective acid. Organic acids had a greater impact on the hydrophobicity of the glass compared to mineral acids, which showed little to no change in the contact angle. A clear correlation between the number of amines and the contact angles of water droplets on the acid-treated glass surface was not found. We demonstrated the reversibility of these reactions for both reaction temperature and drying time parameters. Hydrolysis of the aminosilane layer in the presence of air and water was also observed.
|
