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Features of a non-traditional method of preparation of cellulose-based cation-exchange enterosorbents using nitrogen (IV) oxide are discussed. The proposed approach involves sequential use of oxidative and acid-hydrolyzing functions of nitrogen (IV) oxide to convert ordinary cellulose into carboxylated microcrystalline cellulose. X-ray phase analysis and transmission electron microscopy data show...
Blend hydrogels composed of carboxymethyl chitosan (CMCh) and poly (acrylonitrile) (PAN) were synthesized via crosslinking method. Several analyses were made to investigate both physical and thermal properties of CMCh/PAN hydrogels like; FTIR, scanning electron microscope, XRD and thermogravimetric analysis (TGA). TGA results showed that CMCh/PAN hydrogels are thermally more stable than CMCh and their...
Superabsorbents hydrogel nanocomposites based on starch-g-poly(sodium acrylate) and cellulose nanowhiskers (CNWs) were synthesized. A set of experiments was performed to evaluate the influence of some factors such as NaAc/starch mass ratio, crosslinker, and nanowhiskers amount in the swelling capacity and swelling kinetics. Increasing the NaAc/starch mass ratio up to 7 leads to an increase in the...
Four novel hydrogels composed of carboxymethyl chitosan (CM-chitosan) cross-linked with various contents of terephthaloyl thiourea moieties (TTUCM-chitosan-1, TTUCM-chitosan-2, TTUCM-chitosan-3, TTUCM-chitosan-4) have been successfully synthesized. The hydrogels were characterized by elemental analyses, FTIR, 13C NMR, SEM, XRD, solubility and swell ability in various solvents. The antimicrobial activities...
In this work, we report on the synthesis and characterization of thermoresponsive poly(N-vinylcaprolactam), PNVCL, nanocomposite hydrogels containing nanocrystalline cellulose (CNC) by the use of frontal polymerization technique, which is a convenient, easy and low energy-consuming method of macromolecular synthesis. CNC was obtained by acid hydrolysis of commercial microcrystalline cellulose and...
This study demonstrates the preparation of a renewable and biocompatible co-cross-linked nanocomposite hydrogel from poly(methyl vinyl ether-co-maleic acid), poly(ethylene glycol) and nanofibrillated cellulose (NFC). The cross-linking reaction was favored by the formation of ester linkages as evidenced by Fourier transform infrared spectroscopy. The increase in gel fraction content of the treated...
We report a density functional theory study of cation-induced bonding between carboxylated cellulose nanofibrils (CNFs). We describe a methodology of using cleaved cellulose crystal unit cells to develop simple surface and molecular models of charged CNFs. We compare bond lengths, binding energies, and displaced solvation volumes for interfibril models intercalated with alkali, alkaline earth, main...
The synthesis platform of composite hydrogels containing rigid reinforcing filler cellulose nanocrystals (CNCs) and polymer matrix polyacrylamide (PAM) has been proposed (Yang et al. in Cellulose 20:227–237, 2013). The features of CNCs as multifunctional crosslinkers and flexible polymer chain entanglements contributed to the unique arrangement of CNC/PAM clusters with reversible network structures...
Cellulose nanofibrils (CNF) form hydrogels at low concentrations. These hydrogels are held together by transient interactions such as entanglement of fibrils, non-specific ionic interactions and hydrogen bonds; and are thus vulnerable for changes in the chemical environment or the influence of mechanical forces. By a covalent crosslinking of the fibrils, stable permanent gels can be formed. In this...
Previously, we reported the preparation of high-crystalline hydrogels from α-chitin nanofibers by a simple NaOH treatment at low temperatures. In the present study, mild conditions were applied to both α-chitin powder and nanofibers to make hydrogels using calcium chloride dehydrate-saturated methanol (Ca solvent). Interestingly, nanofibrillation of powder occurred during the treatment. Compared with...
The degradation of archive materials is related to irreversible phenomena induced by light, temperature, humidity, air pollution, micro-organisms, and use. Among biological factors, fungi can induce harmful effects in paper artworks. Further forms of damage (e.g. artwork swelling, fibre lifting and sheet delamination) can be caused by water immersion, which is one of the most commonly used methods...
Cellulose nanocrystals (CNC) can be embedded within hydrogels to form tough and strong nanocomposite materials, which possess biomimetic properties from hydrogels including good biocompatibility, permeability and flexible mechanical characteristics. There are many potential applications for these strong nanocomposite hydrogels in medical devices, such as wound dressing or super absorbents. Whereas,...
Halloysite nanotubes (HNTs) were added to cellulose NaOH/urea solution to prepare composite hydrogels using epichlorhydrine crosslinking at an elevated temperature. The shear viscosity, mechanical properties, microstructure, swelling properties, cytocompatibility, and drug delivery behavior of the cellulose/HNT composite hydrogels were investigated. The viscosity of the composite solution increases...
In this work, a novel poly(ethylene glycol) (PEG)/NaOH system was successfully applied as a co-solvent for two naturally occurring polysaccharides, cellulose (Cel) and sodium alginate (Alg), to obtain biopolymeric films. Different amounts of Cel and Alg were dissolved in aqueous mixtures of PEG and NaOH, cast onto a glass plate, and cross-linked using a combination of physical and chemical cross-linking...
Many load-bearing applications of hydrogels, such as human tissue replacements, require extremely high stiffness, strength and fracture energy, which are rarely achieved simultaneously. Here, we report cellulose nanofiber-based nanocomposite hydrogels, exhibiting highly increased stretchability but with no sacrifice in stiffness when compared with pure rehydrated cellulose nanofiber networks. The...
Interpenetrating polymer network (IPN) hydrogels were prepared by mixing carboxymethyl cellulose (CMC) solution and crosslinked poly(acrylic acid) (cPAA) single IPN hydrogel at mass ratios 100:0, 25:75, 50:50, 75:25 and 0:100 and subsequent crosslinking of CMC chains with citric acid, aimed towards the creation of full IPN hydrogels. The resulting CMC:cPAA hydrogels were freeze-dried for the determination...
Inks for 3D printing based on cellulose nanofibrils (CNFs) or mixtures of CNFs and either cellulose nanocrystals (CNCs) or alginate were assessed by determining their viscoelastic properties i.e. complex viscosity and storage and loss moduli (G′ and G″). Two types of alginates were used, i.e. from Laminaria hyperborea stipe and Macrocystis pyrifera. Shape fidelity of 3D printed grids were qualitatively...
The study concerns the development of rheological properties of aqueous TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)-oxidized nanofibrillated cellulose (NFC) suspensions prepared from a commercially available TEMPO-NFC powder. Ageing of hydrogels with concentrations from 1 to 3 wt% of TEMPO-NFC was investigated by monitoring shear flow and linear viscoelastic properties after different days from sample...
The widely tunable physical and chemical characteristics of hydrogels make them advantageous in biomedical and pharmaceutical applications, yet their hydrophilic nature might discourage their use as drug delivery systems for poorly water soluble molecules. In this work we demonstrate the sustained release of a large amount of a lipophilic drug (clofazimine) from nanocellulose hydrogels. Hydrogels...
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