Superabsorbent nanocomposite hydrogels made of carboxylated cellulose nanofibrils and CMC-g-p(AA-co-AM)

Abstract

Superabsorbents based on carboxylated cellulose nanofibrils (CCNFs) and carboxymethyl cellulose-g-poly(acrylic acid-co-acrylamide) were synthesized. A series of experiments were performed to evaluate the influence of factors such as CCNFs amount, solution pH, temperature, salt solution type and concentration on the swelling behaviors of the hydrogels. The water uptake of the hydrogels strongly depended on the CCNF content, the swelling capacity in distilled water increased dramatically from 245.8 to 458.7 g/g with the addition of CCNFs up to 2.5 wt%. Furthermore, the incorporation of CCNFs improved salt resistance properties of the hydrogels with slower deswelling rate and higher water retention capacity at deswelling equilibrium. Besides, the CCNF nanocomposite hydrogels presented better responsive behavior in relation to pH presence and showed an increase in water retention capacity at various temperatures. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were employed to examine the structure and morphologies of the prepared superabsorbent hydrogels.

Keywords: 2,2,6,6-tetramethylpiperidine-1-oxyl radical; AA; AM; APS; CCNFs; CMC-g-p(AA-co-AM); CNWs; Carboxylated cellulose nanofibrils; FTIR; Fourier transform infrared spectroscopy; MBA; MCC; N,N′-methylenebisacrylamide; SEM; Superabsorbent nanocomposite hydrogels; Swelling behaviors; TEMPO; TEMPO-mediation oxidation; acrylamide; acrylic acid; ammonium persulfate; carboxylated cellulose nanofibrils; carboxymethyl cellulose-g-poly(acrylic acid-co-acrylamide); cellulose nanowhiskers; microcrystalline cellulose; scanning electron microscope.