Nanocellulose as Reinforcement in Carboxymethylcellulose Superabsorbent Nanocomposite Hydrogels

Abstract

Carboxymethylcellulose (CMC) is an abundant and low‐cost material that can be used to synthesize environmentally friendly superabsorbent hydrogels for numerous applications. However, this biopolymer results in hydrogels with poor mechanical properties; different fillers can be used to improve this property, but occasionally can decrease the swelling capacity. Nanocelluloses (NC) are an excellent option to improve hydrogel physicochemical characteristics. In this work, CMC‐hydrogels are prepared using citric acid, and NC is added as a filler in different contents: 1, 3, and 5 wt%. The Fourier Transformed Infrared spectroscopy (FTIR) is used to confirm the crosslink reaction, and a peak related to the carboxylic acid functional group confirmed the hydrogel formation. The NC incorporation didn't change the FTIR spectrum since both materials have a similar structure. The water absorption analysis indicated that the developed can be classified as superabsorbent since all of them show an absorption capacity above 40 g.g−1. Besides that, NC played an essential role in the water absorption capacity, the incorporation of 3% of NC resulted in a material with a degree of swelling of, approximately 100 g.g−1. The NCs act as an excellent filler, improving the storage modulus significantly, i.e., the mechanical resistance of the material. The developed hydrogels showed exceptional characteristics, being adequate to various applications, mainly agricultural ones aiming for the water delivery to the soil.

Engineered Superabsorbent Nanocomposite Reinforced with Cellulose Nanocrystals for Remediation of Basic Dyes: Isotherm, Kinetic, and Thermodynamic Studies

“…Cellulose nanocrystal (CNC) is a highly crystalline nanoparticle obtained by the acid hydrolysis of native cellulose by the removal of the amorphous phase [20]. CNCs are attractive for use as a filler in the hydrogel matrix due to their renewability, abundance, cytocompatibility, and excellent mechanical properties [21,22]. The presence of hydroxyl groups on the surface is responsible for reactivity, hydrophilicity, and the cellulose's physical properties [23,24].…”

Smart carboxymethyl cellulose/polythiophene hydrogel for electrically driven soft actuators: Physical and thermal properties and electroactive performances

“…In addition, the wave number at 1018 cm −1 corresponded to O stretching in the CMC molecular chain 41–43 . After the crosslink reaction, a new band at 1700 cm −1 was observed, indicating the formation of ester bonds which confirmed the crosslinking reaction 42–44 . Crosslinked CMC can absorb large amounts of water (compared to its own mass) and can swell (without dissolving in water) to form hydrogels 28 .…”

“…This anhydride reacted with the hydroxyl functional groups (OH) on CMC polymer chains, leading to the formation of ester bonds. Via this step, citric acid will act as a crosslink agent by forming chemical bonds between CMC polymer chains thus resulting in the network structure of CMC hydrogel as shown in Figure 3 43,44,55 . This intermolecular interaction is needed for water soluble resistance, high water absorbability and strong mechanical properties of the hydrogel.…”

“…Schematic of crosslinking reaction of carboxymethyl cellulose (CMC) with citric acid 44 [Color figure can be viewed at wileyonlinelibrary.com]…”

“…[41][42][43] After the crosslink reaction, a new band at 1700 cm À1 was observed, indicating the formation of ester bonds which confirmed the crosslinking reaction. [42][43][44] Crosslinked CMC can absorb large amounts of water (compared to its own mass) and can swell (without dissolving in water) to form hydrogels. 28 The crosslinking reaction of the polymer matrix is of key importance for the potential use of CMC hydrogels as soft-actuator materials.…”