Highly Elastic Super-Macroporous Cryogels Fabricated by Thermally Induced Crosslinking of 2-Hydroxyethylcellulose with Citric Acid in Solid State

Abstract

Biopolymer materials have been considered a “green” alternative to petroleum-based polymeric materials. Biopolymers cannot completely replace synthetic polymers, but their application should be extended as much as possible, exploiting the benefits of their low toxicity and biodegradability. This contribution describes a novel strategy for the synthesis of super-macroporous 2-hydroxyethylcellulose (HEC) cryogels. The method involves cryogenic treatment of an aqueous solution of HEC and citric acid (CA), freeze drying, and thermally induced crosslinking of HEC macrochains by CA in a solid state. The effect of reaction temperature (70–180 °C) and CA concentration (5–20 mass % to HEC) on the reaction efficacy and physico-mechanical properties of materials was investigated. Highly elastic cryogels were fabricated, with crosslinking carried out at ≥ 100 °C. The storage modulus of the newly obtained HEC cryogels was ca. 20 times higher than the modulus of pure HEC cryogels prepared by photochemical crosslinking. HEC cryogels possess an open porous structure, as confirmed by scanning electron microscopy (SEM), and uptake a relatively large amount of water. The swelling degree varied between 17 and 40, depending on the experimental conditions. The degradability of HEC cryogels was demonstrated by acid hydrolysis experiments.

Functional Hydrogels for Delivery of the Proteolytic Enzyme Serratiopeptidase

“…Consequently, the higher concentration of CA in the reaction mixtures has a positive effect on the cross-linking process. This influence of the crosslinking agent (citric acid) content on the gel fraction yield is in accordance with a previous study [ 21 ].…”

“…We recently reported on the preparation of highly elastic super-macroporous cryogels of biodegradable 2-hydroxyethylcellulose, crosslinked with citric acid. The polymer network was formed in bulk at temperatures above 100 °C [ 21 ]. Sabzi et al have synthesized a pH-sensitive antibacterial drug delivery system from poly(vinyl alcohol) (PVA), CA, and Ag nanoparticles [ 22 ].…”

Preparation and Characterization of Biodegradable Sponge-like Cryogel Particles of Chitosan via the Inverse Leidenfrost (iLF) Effect

“…Biopolymers cannot entirely replace synthetic polymers, but their use should be maximized as much as possible to take advantage of the benefits of their low toxicity and biodegradability. 2 The selection of biodegradable polymers is key to the advancement of modern biomaterials. 3 Chitin is one of the most abundant natural polymers in the world, obtained from crustacean shells, and is used to produce chitosan through deacetylation.…”

“…The massive amount of waste produced by nonbiodegradable synthetic plastics that pollute the environment is one of the primary reasons for searching environmentally friendly alternatives. Biopolymers cannot entirely replace synthetic polymers, but their use should be maximized as much as possible to take advantage of the benefits of their low toxicity and biodegradability . The selection of biodegradable polymers is key to the advancement of modern biomaterials …”

“…Biopolymers cannot entirely replace synthetic polymers, but their use should be maximized as much as possible to take advantage of the benefits of their low toxicity and biodegradability. 2 The selection of biodegradable polymers is key to the advancement of modern biomaterials. 3 …”