Cellulose hydrogels are fabricated directly from native cellulose via cellulose dissolution and subsequent regeneration with water, ethanol, acetone or other polar non-solvents. Cellulose hydrogel’s macromolecules possess the same degree of polymerization as the initial one, indicating no degradation; hydrogels are three-dimensional network structures formed by physical cross-linking of cellulose molecules containing large amount of water. Cellulose hydrogels have many favorable properties such as hydrophilicity, biodegradability, biocompatibility, transparency, low cost and non-toxicity. Therefore, they have wide applications in tissue engineering, controlled delivery system, sensor, water purification, papermaking industry and more.
The cellulose content in the regenerated cellulose hydrogels received from the cellulose solutions of different initial concentrations was investigated by drying of hydrogel samples in a vacuum oven at 60°C at 0.26 kPa for 6 hours. The dependence of cellulose content in hydrogel from initial cellulose concentration is shown in Fig.1.
Fig.1. Dependence of cellulose content and average pore’s diameter in hydrogel on initial cellulose concentration.
The observation of a significant enhancement of the effect of cellulose solution concentration on its content in the hydrogel at about 7 wt.%, can be explained as a manifestation of the creation the cellulose supramolecular structures in solutions. Cryogenic scanning electron microscopy (cryo-SEM) images that were used to measure the pore size of the cellulose network in the different hydrogels (Fig.1), along with small-angle x-ray scattering (SAXS) results, also reflects the same significant change of the hydrogel structure at cellulose initial concentration of about 7 wt.%.
