Anionic and cationic nanocomposite hydrogels reinforced with cellulose and chitin nanowhiskers: effect of electrolyte concentration on mechanical properties and swelling behaviors

Abstract

Various nanocomposite gels were prepared using cellulose nanowhiskers (CNWs) or chitin nanowhiskers (ChNWs) as reinforcing fillers and hydroxypropyl cellulose (HPC), carboxymethyl cellulose (CMC), or chitosan as network polymers. The use of CNWs with low surface charge induced significant CNWs aggregations, which were well explained by depletion effect. Young's modulus E and swelling ratio Q of CNWs/HPC · CMC gels were highest at zero electrolyte concentration and decreased above 0.01 M electrolyte, whereas stress at break σ of the gels showed its minimum at zero electrolytes and increased with an addition of electrolytes. In the case of ChNWs/chitosan gels, maximum of E and Q was located at 0.01 M electrolyte concentration, and σ did not indicate clear tendency with electrolyte concentration. Although all gels indicated an increase in E and a decrease in Q with an increase in whisker content, the most remarkable changes were observed under an absence of electrolytes, whereas the changes under the presence of electrolytes were somewhat negligible.

Review of Hydrogels and Aerogels Containing Nanocellulose

“…Many researchers have focused on creating “all-cellulose” gels with widely available and biocompatible cellulose derivatives. − Notably, McKee et al utilized thermoresponsive methylcellulose networks, which formed hydrogels at elevated temperature and were successfully reinforced by CNCs with the storage modulus increasing by nearly an order of magnitude upon addition of 3.5 wt % CNC . The ability of CNCs to effectively reinforce all natural or all-cellulose polymer networks drastically broadens the potential for CNCs in advanced sustainable/green chemistry applications.…”

Steric Stabilization of “Charge-Free” Cellulose Nanowhiskers by Grafting of Poly(ethylene glycol)

“…Much attention has been focused recently on the utilization of these nanowhiskers as nano-sized fillers in composites, due to their excellent mechanical properties, as well as non-toxicity, biodegradability and ease of large-scale preparation. For example, in the last two decades there have been numerous reports on various types of nanowhisker composites, including films containing matrices of latex or synthetic polymers and fillers of nanowhiskers [19,20,21], high-modulus poly(vinyl alcohol) wet-spun fibers containing uniaxially oriented nanowhiskers [22,23,24,25], hydrogels reinforced by nanowhiskers [26,27] and electrospun fiber mats incorporating nanowhiskers [28].…”

Nanocellulose nanocomposite hydrogels: technological and environmental issues

“…The incorporation of CNCs increased the compression modulus of the pure hydro-gel when compared with hydrogels reinforced with Cloisite Na + nanoclay. Araki et al 99 found similar results using CNCs as a reinforcing agent for CMC/HEC hydrogels. McKee et al 100 reported the formation of a hydrogel after dissolution of MC at 60°C in the presence of CNCs with a storage modulus of 900 Pa.…”