Viscoelastic properties of physical cellulosic bionogels of cholinium lysinate

Abstract

Novel ionogels with different cellulose contents, namely, 0.5, 1, 1.5 and 2 wt%, were formulated with cholinium lysinate (ChLys), and the rheological properties were evaluated at 3 and 7 days postgelation. Because of the biobased compounds contained in these ionogels, in this work, they are denoted as bionogels. These materials have great potential to yield functional biomaterials for use in the medical/pharmacological sector. Some knowledge of how cellulose is dissolved in ChLys was necessary to formulate the bionogels. The dissolution time was studied for each bionogel, with the dissolution times being 3, 4, 4.5, and 6.5 h for 0.5, 1, 1.5, and 2% cellulose, respectively. The bionogel with a 2% cellulose load had the highest rheological properties, i.e. elastic modulus (G'), loss modulus (G″) and complex viscosity (η*), on the studied postgelation days: G' (3 days): 0.7-50 kPa, G' (7 days): 1-100 kPa, G″ (3 days): 0.1-10 kPa, and G″ (7 days): 0.2-20 kPa, η* (3 days): 0.2-200 kPa s and η* (7 days): 0.4-300 kPa s. The postgelation time is an important parameter in the formulation of bionogels, since at 3 days postgelation, the networks continued to be constituted. Regarding classification, these bionogels were weak physical gels.

Keywords: Bionogel; Cellulose; Cholinium lysinate; Ionogel; Rheology.