Poly(vinyl alcohol)/Premna Oblongifolia Merr. Extract/Glutaraldehyde/Carbon Nanotube (VOGC)‐Based Composite Hydrogel: A Potential Candidate for Controlled‐Release Materials

A hydrogel based on poly(vinyl alcohol) (V), Premna Oblongifolia Merr. extract (O), glutaraldehyde (G), and carbon nanotubes (C) has been synthesized in search of candidates to develop controlled‐release fertilizers (CRF). Referring to previous studies, O and C can be considered as two materials that have potential as modifiers in synthesizing CRF. This work is comprised of hydrogel synthesis, their characterisation, including measuring swelling ratio (SR) and water retention (WR) of VOG(m), VOG(e), VOG(m)C(3), VOG(m)C(5), VOG(m)C(7), VOG(m)C(7)‐KCl, and release behaviour of KCl from VOG(m)C(7)‐KCl. We found that C interacts physically with VOG, increased the surface roughness of VOG(m), and reduced the VOG(m) crystallite size. The addition of KCl into VOG(m)C(7) reduced the pore size and increased the structural density of VOG(m)C(7). The thickness and the C content of VOG affected its SR and WR. The addition of KCl into VOG(m)C(7) reduced its SR, but did not significantly affect its WR.