Synthesis and properties of new hydrogel from cross-linked galactomannan boric

A new hydrogel of crosslinked galactomannan boric has been synthesis from galactomannan Arenga pinnata seed (GAP) with boric acid. Galactomannan was isolated from immature Arenga pinnata seed through centrifugation and extracted using ethanol. Cross-linking GAP with boric acid was conducted in the various ratio of GAP and boric acid of 1:0.05 (CGB 1), 1:0.10 (CGB 2), 1:0.20 (CGB 3), 1:0.30 (CGB 4) and 1:0.40 (CGB 5). The product was determined using spectrophotometer infrared which showed the appearance of stretching vibration of B-O at 800 – 1100 cm⁻¹ and the decreasing absorbance at 3394 – 3417 cm⁻¹ which correspondence to stretching vibration of OH group in the increasing of boric acid used. The image of scanning electron microscopic (SEM) of GIB 4 showed the roughness and bumped of the surface morphology of hydrogel compared to the SEM image of GAP. The thickness of the crosslinked films is in the range of 1.42 – 1.98 mm. The maximum swelling value of the hydrogel in aquadest and buffer phosphate solution was obtained in CGB, and the swelling value in 0.9% sodium chloride solution was increased in the increasing of boric acid while all the hydrogel was dissolved in HCl 0.1 N solution. (paper)