Rheology of Laponite-scleroglucan hydrogels

Abstract

a b s t r a c tBoth Laponite and scleroglucan can find several applications in various fields (from industrial to biomedical one) in virtue of their peculiar features and rheological properties displayed in aqueous phases. Structural states of Laponite dispersions strongly depend on concentration and ionic strength. When attractive and repulsive interparticle interactions are so effective that they lead to arrested states (attractive gel or repulsive glass), the rheological behavior of the dispersion undergoes a sharp transition, from quasi-Newtonian to markedly shear thinning and viscoelastic. Conversely, scleroglucan solutions gradually change to weak gels with increasing polymer concentration. The present work is concerned with aqueous Laponite-scleroglucan mixed systems, obtained according to different preparation modes, and is aimed at examining how much the content and proportion of both components affect the viscoelastic and flow properties of the mixed system.

Novel nanobiocomposite hydrogels based on sage seed gum-laponite: Physico-chemical and rheological characterization

“…Based on the results of dynamic oscillatory shear test, it was indicated that Laponite, especially above 5 wt.% content, improved the rheological characteristics performance, attributed to the polymer-particle bridging interaction via the formation of Van der Waals forces, ionic and hydrogen bonds (between the hydrogen and hydroxyl of clay and those of the groups Dglucoronic, D-mannose of the SSG chains), and electrostatic attractions (between anionic groups of SSG molecules and positively charged edges of nanoclay platelets) as already mentioned in literature (Dávila & d'Ávila, 2017;Lapasin et al, 2017;Zlopasa, Norder, Koenders, & Picken, 2016). When nanoparticle concentrations increased, the number and size of agglomerated (soft flocks) and aggregated (hard clusters) SSG-Laponite increased and bridging interaction was strengthened.…”

“…Just recently, rheological characterization of alginate-Laponite and scleroglucan-Laponite hydrogels has been carried out to assay the reinforcing effects of Laponite, in particular to analysis the physical gelation due to the electrostatic interactions between the anionic groups of alginate and scleroglucan chains and positively charged rim of Laponite disks (Dávila & d'Ávila, 2017;Lapasin, Abrami, Grassi, Sebenik, & Šebenik, 2017). Although a lot of facts on…”

Effect of ionic strength on shear-thinning nanoclay–polymer composite hydrogels

“…23 To date, understanding the structural dynamics and aging, 24–27 as well as the rheological properties of Laponite-based systems have been the focus of research. 26,28–33 Depending on the pH, H + or OH − may dissociate from the nanoclay edge. 33 Dissociation of H + from the edge occurs beyond the point of zero charge pH (isoelectric point, pH ~ 11 for Mg-OH), 34 resulting in completely negatively charged particles.…”

Efeito Do Ph, Espécie E Concentração Iônica Na Absorção De Água De Hidrogéis Bionanocompósitos Constituídos De CMC/Paam/Laponita RDS

“…Pode ocorrer periodicamente a substituição dos átomos de magnésio por átomos de lítio (Li), causando uma deficiência de íons positivos que é contraposta pela presença de cátions de sódio (Na + ) presentes nos espaços interplanares. 16 Em recorrência das diferentes propriedades dos hidrogéis citadas anteriormente, os mesmos possuem diversas aplicações, como lentes de contato, 17 tecidos artificiais, 18 sensores e atuadores, 19 tratamentos de câncer, 20 substituição de cartilagens, tratamento de queimaduras, liberação controlada de fármacos, liberação controlada de pesticidas, entre outras. 21,22 Artigo curtos e posteriormente liberar essa água de maneira mais lenta e controlada, agrega-se aos hidrogéis a possibilidade de carregar diversos componentes presentes em soluções aquosas.…”