Stimuli-Responsive Hydrogels Based on Polyglycerol Crosslinked with Citric and Fatty Acids

Abstract

Polyglycerol-based hydrogels from biodegradable raw materials were synthesized by crosslinking reactions of polyglycerol with citric and fatty acids. Three hydrogels were studied varying molar ratios of crosslinking agent. It was found that crosslink amount, type, and size play a crucial role in swelling, thermal, mechanical, and stimuli-responsive properties. The hydrogels absorption capacity changed in response to temperature and pH external stimuli. The hydrogel with the highest swelling capacity absorbed more than 7 times its own weight at room temperature and pH 5. This material increased 14 times its own weight at pH 10. Creep-recovery tests were performed to study the effect of crosslinking agent on mechanical properties. Deformation and percentage of recovery of synthesized hydrogels were obtained. Formation of hydrogels was confirmed using FTIR, and physicochemical properties were analyzed by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetric (DSC), and Dynamic Mechanical Analysis (DMA). This paper aims to give a contribution to biobased hydrogel knowledge from chemical, physicochemical, and mechanical point of view.

Copolymer Based on Polyglycerol-Acrylate-Lactate as Potential Water Viscosifier and Surfactant for Enhanced Oil Recovery

“…Infrared spectroscopy analysis was performed for the three synthesized prepolymers: PRE LA, PRE AA, and PRE AA+LA (supporting information (available here)), polyglycerol, and the copolymers at 30% w/w of each of the synthesized prepolymers (COP 30 w/w% LA, COP 30 w/w% AA, and COP 30 w/w% LA+AA). 1(a) shows the infrared spectra of synthesized polyglycerol, which is in agreement with our previous reports [21,36]. Accordingly, polyglycerol exhibits its characteristic O-H band from 3600 to 3050 cm -1 .…”

“…Processes. Preliminary glycerol polymerization tests were performed according to previous works [21,36]. Accordingly, the initial glycerol amount and sulfuric acid (1% w/w) were stirred at 500 rpm for 5 min at room temperature.…”

“…From the esterified polymers, only the esterified at 5% with oleic acid (COP 30 w/w% AA+LA-5% AO) was effectively dissolved in distilled water. It was not possible to dissolve the esterified polymer with 10% of oleic acid, probably caused by crosslinking reactions between copolymer and the oleic acid [36,49]. The resulted measurements of esterified samples showed that after the addition of oleic acid, the viscosity decrease to 1 cP.…”

Synthesis and characterization of a Schiff base crosslinked hydrogel based on hyperbranched polyglycerol

“…The number of glycidol units can be calculated similar to the reported method for hPG-co-AGE. It can be calculated using eqn (2). §…”

Screening and optimization through response surface methodology for synthesis of pH, temperature and salt‐sensitive Aloe vera–acrylic acid‐based biodegradable hydrogel: Its evaluation as dye adsorbent

“…The polymer so synthesized is used for the sorption of dyes [14]. Thermal-, pH-, and magnetic-sensitive nanogel was prepared by modifying sodium alginate through grafting by N-isopropyl acrylamide and acrylic acid (AA) and used for drug delivery [15]. As it is clear from the literature review that very little work was done on the modification of Aloe vera, so in the present work naturally occurring Aloe vera was modified by grafting and used as stimulusresponsive hydrogel rather than using chemical-synthesized polymer like polyglycerol-based hydrogel [16].…”