Hydrogels of starch/carboxymethyl cellulose crosslinked with sodium trimetaphosphate via reactive extrusion

Abstract

Hydrogels are materials with advantages in specific applications, such as, retention of food active compounds. This work aims to develop starch (S)/carboxymethyl cellulose (CMC) hydrogels with porous structure, using reactive extrusion to promote crosslinking with sodium trimetaphosphate (STMP). The expansion, porosity, degree of substitution, gel fraction, swelling properties, and FTIR are studied, comparing S, S/CMC, S/STMP, and S/CMC/STMP formulations. Samples containing STMP present the same degree of substitution (0.050 ± 0.001). Higher porosity and percentage of open pores are observed in the mixed hydrogel (S/CMC/STMP). Crosslinking increase the swelling capacity at pH 7, and this property, just like the gel fraction, are sensitive to pH variations. The hydrogel S/CMC present the highest swelling rate compared with the other samples, suggesting strong interaction between components. The reactive extrusion process is efficient to produce starch and starch/CMC hydrogels crosslinked with STMP and the overall results demonstrate the advantages of the mixed hydrogel.

Starch-cellulose-gelatin hydrogels obtained by reactive extrusion aiming an ecologically friendly perspective

“…DS can be consider a good indicative of the occurrence of crosslinking of the phosphate groups grafted onto the polysaccharides chain [23,32,33]. The value observed in this study was lower when compared to DS reported by Cagnin et al [23,24], who reported DS values of 0.05 for hydrogels obtained by reactive extrusion from cassava starch and carboxymethylcellulose crosslinked with STMP (4 g/100 g).…”

“…Degree of substitution (DS) of modi ed starch was calculated according to Volkert et al [27] by titration. For modi ed cellulose, the phosphorus content (%) was analyzed in triplicate by colorimetry in 600 nm (spectrophotometer Varian -Cary 50 Conc, São Paulo, Brazil) and DS was calculated as follows [24]: DS = 162*P/ (3100 − 102*P), where: P is phosphorus content (%); 162 is the molecular weight of the monomeric unit of cellulose, 3100 is the atomic weight of phosphorus multiplied by 100; and 102 is the group phosphate weight.…”

“…While these variables typically increase hydrogel porosity, in this study, the same conditions were standardized for all samples, attributing differences in results to formulation components. Cagnin et al [24] reported lower porosity values (below 11%) for carboxymethylcellulose and starch hydrogels obtained by reactive extrusion using STMP as a crosslinking agent, highlighting the in uence of raw materials and processing conditions.…”

Superabsorbent cellulose-based hydrogels cross-liked with borax

“…However, the main disadvantage of this method is the toxicity of residual cross-linking agents. Therefore, there are many efforts to use low toxic crosslinkers such as carbodiimide 15 , borax 12 , 16 , 17 , sodium trimetaphosphate 18 , 19 , N,N′-methylene bisacrylamide 20 , and polycarboxylic acids 21 – 23 .…”

A hydrogel sensor driven by sodium carboxymethyl starch with synergistic enhancement of toughness and conductivity

“…Carboxymethyl starch sodium (CMS) is a derivative of starch with excellent biocompatibility and stability, which is widely used in diverse fields of petroleum, food, medicine and sensing. [26][27][28][29][30][31] The particular molecular construction of CMS presented the capacity for constructing non-covalent interactions because it provided plenty of hydroxyl groups to supply the sites of physical cross-linking. 32,33 Furthermore, the CMS possesses free-moving sodium ions, which makes hydrogels ideal conductors.…”