Access to clean water has become increasingly difficult, motivating the need for materials that can efficiently remove pollutants. Hydrogels have been explored for remediation, but they often require long times to reach high levels of adsorption. To overcome this limitation, we developed a rapid, locally formed hydrogel that adsorbs dye during gelation. These hydrogels are derived from cellulose—a renewable, nontoxic, and biodegradable resource. More specifically, we found that sulfated cellulose nanofibers or sulfated wood pulps, when mixed with a water-soluble, cationic cellulose derivative, efficiently remove methylene blue (a cationic dye) within seconds. The maximum adsorption capacity was found to be 340 ± 40 mg methylene blue/g cellulose. As such, these localized hydrogels (and structural analogues) may be useful for remediating other pollutants. 相似文献
New composite hydrogels based on cellulose and poly(acrylamide) have been synthesized via radical polymerization of acrylamide in cellulose swollen in a reaction solution. In this study, both a plant form of cellulose and a bacterial form—that cultivated by Acetobacter xylinum bacteria—were used. The behavior of synthesized hydrogels during swelling in water, as well as the behavior of the samples swollen at equilibrium during deformation under uniaxial compression under various test conditions, have been studied. A comparative analysis of the main mechanical characteristics of hydrogels and the appropriate data for various types of articular cartilage, one of which—rabbit knee meniscus—has been tested in this study, has been performed. An average-strength hydrogel is very close to articular cartilage in all mechanical characteristics. The degrees of loading at the highest compression deformations observed during the function of joint cartilage (30–50%) is in the range 4–12 MPa for this hydrogel, and the average values of the compression modulus in the deformation ranges of 10–15 and 25–30% are 8.8 and 23.7 MPa, respectively. The behavior of hydrogels and rabbit meniscus under cyclic compression with the amplitude of 50% has been studied. Hydrogels and meniscus under this test conditions demonstrate clear viscoelastic behavior, evidenced by noticeable hysteresis for the first cycle and a decrease in the value of the maximum load with an increase in the number of cycles. Structural features of hydrogels, which can affect the behavior of the hydrogels under study, have been considered. On the whole, the results demonstrate the possibility of modeling the mechanical behavior of cartilage with the use of hydrogels of this type. 相似文献
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 with the addition of HNT. The compressive mechanical properties of composite hydrogels are significantly improved compared with pure cellulose hydrogel. The compressive strength of the composite hydrogels with 66.7% HNTs is 128 kPa, while that of pure cellulose hydrogel is only 29.8 kPa in compressive strength. Rheological measurement suggests the resistance to deformation is improved for composite hydrogels. X-ray diffraction and Fourier transform infrared spectroscopy show that the crystal structure and chemical structure of HNT are not changed in the composite hydrogels. Hydrogen bonding interactions between HNT and cellulose exist in the composites. A porous structure of the composite hydrogels with pore size of 200–400 μm was found by scanning electron microscopy. The addition of HNT leads to decreased swelling ratios in NaCl solution and pure water for the composite hydrogels. Cytotoxicity assays show that the cellulose/HNT composite hydrogels have a good biocompatibility with MC3T3-E1 cells and MCF-7 cells. Curcumin is further loaded into the composite hydrogel via physical adsorption. The curcumin-loaded composite hydrogels show a strong inhibition effect on the cancer cells. All the results illustrate that the cellulose/HNT composite hydrogels have promising applications such as anticancer drug delivery systems and anti-inflammatory wound dressings. 相似文献
In this work, de-watered cellulose pulp(DCP), obtained from a paper mill, have been acid-hydrolyzed to yield cellulose nano-whiskers (CNWs). As revealed from FESEM measurements, these CNW were found to possess a median length of 258.5 nm, diameter of 35.2 nm, and an aspect ratio of 7.3. The CNWs were also characterized by TGA, XRD and FTIR analysis. The CNWs were found to possess a fairly high Crystallinity Index (CI) of 0.925. The addition of cellulose at low concentration range, i.e., from 25 to 125 mg (nearly 1.25 to 6.25 weight percent of polymer sodium acrylate) caused an enhancement in water uptake of resulting hydrogels .The CNWs-loaded poly(SA) hydrogels showed chain relaxation controlled swelling in the medium of pH 7.4 as was confirmed from the swelling exponent ‘n’ values obtained using power function law‥ The second order kinetic model was found to fit well to the kinetic water uptake data. However, all the samples, when prepared in the form of films, did not show any remarkable increase in their mechanical strength. 相似文献
This paper reviews briefly our preliminary results concerning thermoplastic hydrogels and thermotropic aqueous gels from cellulose. Several kinds of thermoplastic hydrogels and thermotropic aqueous gels were prepared from cellulose and their thermal properties were examined. The former aims at preparing water-insoluble cellulose derivatives having a high water absorbency and a thermal flow temperature of approximately 130°C, while the later aims at preparing water-soluble cellulose derivatives which show a solubility behavior similar to that of synthetic polymers with a lower critical solution temperature (LCST) in aqueous solution. The results will be discussed in terms of the chemical structure of the prepared derivatives and their substituent distributions along the cellulose chain. 相似文献
Fabricating mechanically strong hydrogels that can withstand the conditions in internal tissues is a challenging task. We have designed hydrogels based on multicomponent systems by combining chitosan, starch/cellulose, PVA, and PEDOT:PSS via one-pot synthesis. The starch-based hydrogels were homogeneous, while the cellulose-based hydrogels showed the presence of cellulose micro- and nanofibers. The cellulose-based hydrogels demonstrated a swelling ratio between 121 and 156%, while the starch-based hydrogels showed higher values, from 234 to 280%. Tensile tests indicated that the presence of starch in the hydrogels provided high flexibility (strain at break?>?300%), while combination with cellulose led to the formation of stiffer hydrogels (elastic moduli 3.9–6.6 MPa). The ultimate tensile strength for both types of hydrogels was similar (2.8–3.9 MPa). The adhesion and growth of human osteoblast-like SAOS-2 cells was higher on hydrogels with cellulose than on hydrogels with starch, and was higher on hydrogels with PEDOT:PSS than on hydrogels without this polymer. The metabolic activity of cells cultivated for 3 days in the hydrogel infusions indicated that no acutely toxic compounds were released. This is promising for further possible applications of these hydrogels in tissue engineering or in wound dressings.
Blend hydrogels based on the carboxymethyl cellulose (CMC) and carboxymethyl chitosan (CMCts) were prepared by γ-irradiation of a high concentrated CMC/CMCts aqueous solution. Properties of the hydrogels, such as gel fraction, swelling ratio, gel strength, and metal adsorption for Pb and Au were investigated. The gel fraction increased with increasing dose, while the swelling ratio decreased with increasing it. The obtained blend hydrogels had high adsorption performance which was controlled by adjusting the composition of CMC/CMCts. 相似文献
In this work, epichlorohydrin (Ech) crosslinked cellulose hydrogels have been prepared and loaded with urea (Ur) for controlled release as a fertilizer. A detailed study of swelling behavior of these hydrogels and their urea releasing capacity has been carried out under various experimental conditions. The dynamic swelling and release data has been applied on various kinetic models. Finally, using a novel Sprinkler Based Irrigation (SBI) model, a model plant has been irrigated with water in the presence of urea-loaded hydrogel. It was found that plants, irrigated in the presence of urea-loaded hydrogel exhibited a better growth as compared to the control plant sample. 相似文献
In this study, a non-cytotoxic and pH-sensitive poly(acrylamidoglycolic acid) based nanocomposite (PAGA-NC) hydrogels reinforced with cellulose nanocrystals (CNCs) was synthesized using redox free radical polymerization. The successful formation and crystalline behaviour of PAGA-NC hydrogels was verified by fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analyses. The results showed that morphological, rheological and mechanical properties of the PAGA-NC hydrogels were strongly influenced by the CNCs content. Moreover, swelling properties were investigated, and the results suggested that they behaved as pH sensitive manner. The in vitro MTT assay showed that the PAGA-NC hydrogels are cytocompatibile to NIH-3T3 fibroblast cells. In addition, diclofenac sodium (DCF) model drug was successfully encapsulated into these PAGA-NC hydrogels via equilibrium swelling method. The in vitro release of DCF from PAGA-NC hydrogels was retained at pH 1.2 and maximum release was observed at 7.4, revealing as potential candidates for controlled release carriers for oral drug delivery applications. 相似文献
Novel cellulose hydrogels were synthesized through a "one-step" method from cellulose, which was dissolved directly in NaOH/urea aqueous solution, by using epichlorohydrin as crosslinker. Structure and properties of the hydrogels were characterized by using SEM, NMR, and water absorption testing. The hydrogels are fully transparent and display macroporous inner structure. The equilibrium swelling ratios of the hydrogels in distilled water at 25 degrees C are in the range from 30 to 60 g H(2)O/g dry hydrogel. Moreover, the reswelling water uptake of the hydrogels could be achieved to more than 70% compared with their initial swelling states. This work provided a simple and fast method for preparing eco-friendly hydrogels from unsubstituted cellulose. 相似文献
Novel superabsorbent hydrogels were prepared successfully from carboxymethylcellulose sodium (CMC) and cellulose in the NaOH/urea aqueous system by using epichlorohydrin (ECH) as cross-linker. The structure and morphology of the hydrogels were characterized by FT-IR spectroscope, thermogravimetric analysis and scanning electron microscope. The results revealed that the CMC contributed to the enhanced size of pore, whereas cellulose as a strong backbone in the hydrogel to support it for keeping its appearance. Their equilibrium swelling ratio in distilled water and different physiological fluids were evaluated, indicating the maximum swelling ratio in water reached an exciting level of 1000 as the hydrogels still keeping a steady appearance. Moreover, the hydrogels exhibited smart swelling and shrinking in NaCl or CaCl2 aqueous solution, as well as the release behavior of bovine serum albumin (BSA) that could be controlled by changing CMC content. The cellulose-based hydrogels are promising for the applications in the biomaterials area. 相似文献
Reinforcement of polyvinyl alcohol (PVA) hydrogels was achieved by direct chemical cross-linking of surface modified microcrystalline cellulose (MCC) whiskers with PVA. In order to produce hydrogels, the MCC whiskers were first obtained by TEMPO-mediated oxidation of the cellulose substrate and ultrasonication followed by direct cross-linking to PVA (Mw 98,000) via forming acetal bonds and freeze–thawing. The viscoelastic properties of the produced hydrogels were clearly improved following the chemical cross-linking, featuring values for viscous and elastic moduli G′ and G″ on the order of 10 kPa, which is particularly interesting for biomedical orthopedic applications. 相似文献
The use of π‐conjugated polymers (CPs) in conductive hydrogels remains challenging due to the water‐insoluble nature of most CPs. Conjugated polyelectrolytes (CPEs) are promising alternatives because they have tunable electronic properties and high water‐solubility, but they are often difficult to synthesize and thus have not been widely adopted. Herein, we report the synthesis of an anionic poly(cyclopentadienylene vinylene) (aPCPV) from an insulating precursor under mild conditions and in high yield. Functionalized aPCPV is a highly water‐soluble CPE that exhibits low cytotoxicity, and we found that doping hydrogels with aPCPV imparts conductivity. We also anticipate that this synthetic strategy, due to its ease and high efficiency, will be widely used to create families of not‐yet‐explored π‐conjugated vinylene polymers. 相似文献
Thermo-sensitive poly (N-isopropylacrylamide) (PNIPA) hydrogel with fast response rate was prepared by polymerizing N-isopropylacrylamide (NIPA) in an aqueous hydroxyl-propyl-methyl cellulose solution. The volume phase transition temperature
of PNIPA hydrogels was characterized by differential scanning calorimetry (DSC), and the surface morphology was observed by
scanning electron microscopy (SEM). The swelling ratios of the hydrogels at different temperatures were measured. Furthermore,
the deswelling kinetics of the hydrogels was also studied by measuring their water retention capacity. In comparison with
a conventional PNIPA hydrogel prepared in water, the hydrogel synthesized in aqueous hydroxyl-propyl-methyl cellulose solution
has higher swelling ratios at temperatures below the lower critical solution temperature and exhibits a much faster response
rate to temperature changes. For example, the hydrogel made in aqueous hydroxyl-propyl-methyl cellulose solution lost 89%
water within 1 min and about 93% water in 4 min, whereas the conventional hydrogel lost only about 66% water in 15 min from
the deswelling measurement in similar conditions.
Translated from Chinese Journal of Applied Chemistry, 2006, 23(6): 581–585 (in Chinese) 相似文献
The adsorption of phosphate ions from aqueous solutions with an ionic strength of 0.5 on iron(III), zirconium(IV), and chromium(III) oxyhydroxide hydrogels has been studied as influenced by chloride and sulfate ions. Despite the high concentrations of chloride and sulfate ions, they do not inhibit phosphate adsorption on the hydrogels; they only slightly change the isotherm shape. In the range of equilibrium phosphate concentrations equal to 30–50 mmol/l, all isotherms for iron and zirconium oxyhydroxide gels signify the appearance of a second adsorption layer (two-step isotherms). Both steps are satisfactorily fitted by the Langmuir equation. The maximum adsorptions and adsorption constants have been calculated. For chromium oxyhydroxide gels, the intraduction of an electrolyte dramatically decreases the equilibration rate. 相似文献