Agarose based multifunctional materials: Evaluation of thixotropy, self-healability and stretchability

This paper reports a microwave assisted one pot facile synthesis of ester derivatives of agarose (Agr-GA(Est)) through chemical reaction of agarose (Agr) with gallic acid (GA), an organic acid found in many plants employing carbodiimide chemistry. Agr-GA(Est) was characterised by FT-IR, C-13 NMR spectroscopy, thermogravimetric analysis (TGA), DMA measurements, scanning electron microscopy (SEM), UV-vis spectrophotometry and rheometry. The native agarose was insoluble in ethylene glycol, but Agr-GA(Est) (obtained at an optimized molar ratio of 1: 0.5) formed good quality gel (tan delta similar to 0.1) at 4% (w/v) concentration. The gel thus obtained exhibited substantial degree of thixotropy (hysteresis loop area = 38.73%), rapid self-healing ability (12 min) upon complete cleavage of the gel and excellent stretching ability (>20 times of its original length). These types of multifunctional gels would find applications in food and personal health care industries. (C) 2014 Elsevier Ltd. All rights reserved.