Preparation of Cellulose Hydrogels Modified with (2-Dimethylaminoethyl) Methacrylate and Silver Nanoparticles

Hydrogels are materials displaying the ability to absorb large amounts of water. Cellulose is a wide-spread, biocompatible, and biodegradable polysaccharide with hydrophilic OH groups in a struc-ture that allows various modifications. By introducing new functional groups to the repeating units of the polysaccharide chain, it is possible to modify properties of the material in order to prepare hydrogels of desired properties such as antibacterial properties or response to external stimuli. In this work, 2-dimethylaminoethyl methacrylate (DMAEMA) grafting on cellulose was performed. The polymerization of DMAEMA on cellulose was carried out in solvent N,N-dimethyl acetamide / LiCl with a peroxide initiator at 90 degrees C and N,N-methylene-bis-acrylamide (MBA) as a crosslinker. Nanoparticles of silver, well known for their antibacterial properties, were also introduced into the prepared hydrogels. The relative proportion of PDMAEMA in hydrogels was determined by infrared spectroscopy. The morphology of the dried samples and the presence of silver were deter-mined by scanning electron microscopy, which showed that the addition of PDMAEMA and drying of the hydrogels by freeze-extraction resulted with a very porous structure. In this way, the binding of silver nanoparticles to hydrogels was also facilitated. Samples of copolymers prepared by drying in a dryer showed a higher degree of swelling in water (similar to 109 %) than pure cellulose (80 %). The same materials prepared by freeze-drying formed into porous hydrogels showed much higher swelling rates (256 % and 505 %) compared to pure cellulose (80 %).