A hypromellose-graft-poly(acrylic acid)
(HPMC-g-PAA) superabsorbent resin was synthesized
through the
graft polymerization of hydroxypropyl methylcellulose and acrylic
acid in an aqueous solution by UV polymerization, with the addition
of an initiator and cross-linking agent. Additionally, the HPMC-g-PAA/urea composite was synthesized by using a one-pot
method to create a slow-release fertilizer by incorporating urea into
the structure of superabsorbent materials. The structures of HPMC-g-PAA and HPMC-g-PAA/urea were characterized
by FTIR, TGA and SEM. The effects of preparation conditions such as
UV exposure time, HPMC content, neutralization degree, initiator amount,
amount of cross-linking agent, and urea content on the water absorption
capacity of the superabsorbent polymers were evaluated. Under optimal
conditions, the HPMC-g-PAA exhibited a maximum absorption
capacity of 1567 g/g in distilled water and 88.5 g/g in NaCl solution
(0.9 wt %). Similarly, the HPMC-g-PAA/urea demonstrated
a maximum absorption capacity of 1382 g/g in distilled water and 82.3
g/g in NaCl solution (0.9 wt %). The comprehensive investigation encompassed
the assessment of slow-release and water-retention properties, as
well as a growth experiment conducted on the samples. The slow-release
period of sample reached 93% at the 26th hour. The obtained results
unequivocally validate the effectiveness of the synthesized superabsorbent
resin and slow-release fertilizer in significantly enhancing plant
growth.