Novel superabsorbent cellulose‐based hydrogels crosslinked with citric acid

Abstract

This work is focused on the preparation of new environmentally friendly hydrogels derived from cellulose and hence originating from renewable resources and characterized by biodegradable properties. Two cellulose derivatives, sodium carboxymethylcellulose (CMCNa) and hydroxyethylcellulose (HEC), were used for superabsorbent hydrogel preparation. Citric acid (CA), a crosslinking agent able to overcome toxicity and costs associated with other crosslinking reagents, was selected in a heat activated reaction. Differential scanning calorimeter (DSC), fourier transform infrared spectroscopy (FTIR), and swelling measurements were performed during the reaction progress to investigate the CA reactivity with each of the polymers. Also, CMCNa/HEC polymer mixtures (3/1 w/ w) crosslinked with CA were investigated and compared with previous results. Finally, a possible reaction mechanism was proposed.

Enhanced Absorbent Products Incorporating Cellulose and Its Derivatives: A Review

“…As was noted earlier, the highest recorded values of swelling tend to be associated with the lowest practical (and sometimes impractical) extents of crosslinking (Bin et al 2000;Wach et al 2001Wach et al , 2002Liu et al 2005a;Demitri et al 2008;Han et al 2010;Pourjavadi et al 2010;Kono and Fujita 2012). The basis for this relationship is illustrated in Fig.…”

“…Water absorbency values generally in the range of 40 to 1400 g/g have been reported in such studies, with the highest value reported by Pourjavadi et al (2008). Copolymers incorporating CMC have also been prepared with polyvinyl alcohol (El Salmawi 2007), hydroxyethyl cellulose (Oppermann 1995;Lionetto et al 2003;Sannino and Nicolais 2005;Demitri et al 2008;Dai and Kadla 2009), and with hydroxypropylethyl cellulose (Faroongwarng and Sukonrat 2008).…”

“…In an analogous manner to CMC, other cellulose ethers or esters have been used as a basis for forming hydrogels, either alone or in combination with other polymers (Harsh and Gehrke 1991;Oppermann 1995;Kabra et al 1998;Bourges et al 2002;Wach et al 2002;Lionetto et al 2003;Demitri et al 2008;Joshi et al 2008;Dai and Kadla 2009;Bao et al 2012). Bao et al (2012) observed higher absorbency in superabsorbents made from graft copolymers of CMC, in comparison with graft copolymers from hydroxypropyl methyl cellulose, methyl cellulose, and hydroxyethyl cellulose.…”

“…As one might expect based on environmental concerns, many researchers have investigated the preparation of "all-natural-based" hydrogels incorporating cellulose or its derivatives (Harsh and Gehrke 1991;Barbucci et al 2000;Bin et al 2000;Fei et al 2000;Wach et al 2001Wach et al , 2002Hirsh and Spontak 2002;Liu et al 2002Liu et al , 2005aRodriguez et al 2003;Sannino et al 2003Sannino et al , 2004aSannino and Nicolais 2005;Yoshimura et al 2006;Demitri et al 2008;Faroongwang and Sukonrat 2008;Pourjavadi et al 2008Pourjavadi et al , 2010Chang et al 2009Chang et al , 2010Dai and Kadla 2009;El Salmawi and Ibrahim 2011;Salam et al 2011a,b;Wang et al 2011b;Kono and Fujita 2012;Pan and Ragauskas 2012;. For instance, a hydrogel based on a combination of cellulose and CMC can be prepared from a solution of the ingredients in a NaOH/urea solvent system .…”

“…Though the highest swelling performance is often observed at the lowest levels of crosslinking (Bin et al 2000;Wach et al 2001Wach et al , 2002Liu et al 2005a;Demitri et al 2008;Han et al 2010;Pourjavadi et al 2010;Kono and Fujita 2012), it is generally observed that higher levels of crosslinking (or other reinforcement) are needed to achieve the needed mechanical resilience and resistance to dissolution of superabsorbent products (Guilherme et al 2005;Myung et al 2008;Tanaka et al 2005;Schexnailder and Schmidt 2009;Zohuriaan-Mehr et al 2010).…”