Imparting superhydrophobicity to surfaces has direct implications for developing water-repellent materials. Most hydrophobic materials cannot be applied directly to specific surfaces like leather because of noncompatibility. Although methacrylic polymers are compatible to leather, their inherent hydrophilic characteristics make it challenging to use for introducing hydrophobicity or superhydrophobicity. In this article, we present a strategy of introducing hydrophobicity in various degrees as well as superhydrophobicity to different surfaces, particularly leather and glass surfaces by using conjugates of methacrylic polymers and various carbon nanomaterials. The covalent functionalization of methacrylate polymers with carbon nanotubes and fullerenes was performed by radical polymerization in the presence or absence of chain transfer agents (CTAs). CTA was used during polymerization to introduce carboxylic acid group, necessary for chromium-assisted binding to leather to avoid leaching. A balance between the compatibility of the polymer nanoconjugates with the leather and the amount necessary for coating stabilization was studied by a rheometer. While water contact angle measurement indicated the mild hydrophobicity in most cases, we were delighted to observe superhydrophobicity in one case presumably due to increased roughness because of the presence of specific nanomaterial to overcome inherent hydrophilicity of methacrylic polymers.
In this paper, the authors report the preparation of pH-responsive microcapsules using poly(methacrylic acid) and different carbon nanomaterials, graphene oxide (GO) and fullerenol (FOH). Potential non-covalent interactions, as well as a comparative study in terms of stability and structural/morphological aspects of the graphene oxide microcapsules (MGO) and fullerenol microcapsules (MFOH), were carried out using Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry analysis, field emission scanning electron microscopy and high-resolution transition electron microscopy. The comparative drug release study for MGO and MFOH was done using ultraviolet illumination, fluorescence spectroscopy and so on. It was observed that the release of the drug (riboflavin) at pH 4 from MGO was faster, reaching the saturation point before 12 h, compared to that in MFOH, where the saturation point was achieved after 18 h. To the best of the authors’ knowledge, this is the first report on a comparative study of MGO and MFOH in terms of their stability, pH-responsive nature and other characteristics. This study can be utilized where the carbon nanomaterials (GO/FOH) are used in the preparation of designer microcapsules for targeted drug delivery applications, since the pH varies in different parts of the human body.
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