Silver nanoparticles (AgNPs) stabilized by sodium carboxymethylcellulose (Na‐CMC) with degree of substitution (DS) 0.65‐0.90 and degree of polymerization (DP) 200‐600 were synthesized by photochemical method. The structural, physico‐chemical, and physico‐mechanical properties as well as antimicrobial activity of polymer films containing the Na‐CMC and AgNPs were studied. The shape, quantity, and size of the AgNPs embedded into the Na‐CMC films were determined by UV‐Vis spectroscopy, ZETASIZER Nano ZS, atomic force microscopy and transmission electron microscopy. It was found that the increase of silver nitrate concentration in solution of Na‐CMC followed by photoirradiation leads to the change of size and shape of AgNPs. The AgNPs in the range of size from 5 to 35 nm were found to enhance the microbicidal activities of the Na‐CMC films.
Nanocellulose is a new class of derivatives of cellulose, which is characterized by high crystallinity, surface area, degree of dispersion, ability to decomposition by microorganisms and etc. There is high attention solving problems of obtaining nanocellulose and its application as high quality filler for polymers, biodegradable materials, additives for papers, clotting dispersion and etc. Obtaining of particles of nanosized nanostructure on the base cellulose, studying of processes of their formation, properties and creation nanotechnology on this basis give the chance to obtain materials with unique properties. In this work nanocellulose was obtained from cotton cellulose by hydrolysis with sulfuric acid, ultrasonic dispersion and microwave irradiation. The properties and structure of nanocellulose are investigated by AFM, IR-spectroscopic, X-ray methods. Nanocellulose has rod-like shape with sizes 50-300 nm in length and 10-40 nm in diameters and spherical shape with sizes 50-300 nm depending on the synthesis conditions of obtaining. Quantum-chemical methods have been used to calculate the electronic characteristics of nanocellulose; the change in the energy difference between HOMO and LUMO is shown, showing the change in reactivity and the manifestation of specific properties.
The shape, number, and size of silver nanoparticles contained in cotton cellulose and its derivatives were studied using x-ray diffraction, atomic absorption spectroscopy, transmission electron microscopy, and elemental analysis. Silver nanoparticles in sodium carboxymethylcellulose were smaller and more numerous and had a more even distribution than those in cotton and microcrystalline cellulose. The size and shape of silver nanoparticles depended on the nature of the polymer matrix.Ultradispersed metals exhibit unusual properties that open new possibilities for their practical application. Silver nanoparticles, which are an antimicrobial agent, are especially interesting. Several methods for producing stable metal nanoparticles, including chemical, biochemical, physical, and others, are known.The synthesis of metal clusters and nanoparticles in polymer solutions and matrices is a vigorously developing area for preparing nanostructured metal-containing systems with an array of unusual physicochemical properties [1].Research in this area indicates that macromolecules not only stabilize dispersed systems but also participate directly in their formation by controlling the size and shape of the growing nanoparticles [2]. The use of natural polymers as the polymer matrices for growing metal nanoparticles is even more attractive because they can undergo biodegradation.Therefore, it seemed promising to study the structures and properties of cotton cellulose derivatives containing silver nanoparticles. We studied previously the ability to prepare silver nanoparticles in matrices of cellulose derivatives and showed that the resulting materials acquired new, in particular bactericidal, properties that were uncharacteristic fon the starting materials [3].The goal of the present work was to study cotton cellulose derivatives (microcrystalline and carboxymethylated cellulose) containing silver nanoparticles using physical and physicochemical methods.X-ray diffraction studies showed ( Fig. 1) that carboxymethylcellulose (CMC) had an amorphous structure and gave a diffuse ring at 2T = 21.6°. CMC containing silver ions also had an amorphous structure with a weaker ring in the same region. Two phases were found in diffraction patterns of polymeric CMC composite with reduced silver nanoparticles. These corresponded to amorphous CMC at diffraction angle 2T = 21.6° and metallic silver. Silver with a cubic crystal lattice and a = 4.086 A° gives reflections at 2T = 38°, 44°, 65°, and 78° from planes (111), (200), and (220) [4].The size of the silver crystallites was calculated from the peak widths. The width of x-ray diffraction peaks is known to depend on the size of the crystallites and their coherent scattering regions. The greater the size of these regions is, the narrower the reflection in the x-ray pattern. The effective crystallite sizes were determined using the Scherrer formula and the width of each line.The effective size of the silver crystals in the CMC matrix was 15 nm according to the calculations. Figure 2 shows high-a...
Nanocellulose (NC) derivatives are being used in a wide variety of high-quality functional applications.One of them is oxidized nanocellulose (ONC), which has been used in biomedical and pharmaceutical applications due to its biodegradable, biocompatible, hemostatic, and antibacterial properties. In this work, ONC was synthesized using potassium dichromate as an oxidizing agent. The structure of ONC was investigated by means of ultraviolet spectrophotometry (UV), fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The results showed that the primary hydroxyl groups of NC were selectively oxidized to carboxyl groups and their content of 1.36 mmol/g was achieved. The appearance of a new peak (1721 cm − 1 ) in the FTIR-spectra related to the C = O group was observed. The change of ONC degree of crystallinity (DC) from 88.0-82.5% was revealed and the sizes of the unit cells of both NC and ONC were calculated. The thermal stability of ONC decreased compared to NC. The oxidation process of NC leads to a change in the shape and size of particles from acicular to spherical with a narrow particle size distribution. It was shown that ONC has the ability to accumulate charge on its surface.
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