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

Abstract

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 VOGm, VOGe, VOGmC3, VOGmC5, VOGmC7, VOGmC7-KCl, and release behaviour of KCl from VOGmC7-KCl. We found that C interacts physically with VOG, increased the surface roughness of VOGm, and reduced the VOGm crystallite size. The addition of KCl into VOGmC7 reduced the pore size and increased the structural density of VOGmC7. The thickness and the C content of VOG affected its SR and WR. The addition of KCl into VOGmC7 reduced its SR, but did not significantly affect its WR.