Presence Of Sodium Alginate Research Articles

Extraction and characteristic properties analyses of sodium alginate derived from the Sargassum oligocystum brown seaweed alga of the Bay of Bengal

Sodium alginate extracted from Sargassum oligocystum brown seaweed alga is an important blue economy development process of the Bay of Bengal. In the present study, sodium alginate was extracted from the brown seaweed alga collected from the Cox’s Bazar coastal area of the Bay of Bengal. The extracted product was characterized with the Ultraviolet-visible (UV–visible) spectrophotometer, Fluorescence spectrophotometer, Fourier transform-infrared radiation (FT-IR) spectrophotometer, X-ray diffractometer (XRD), and Scanning electron microscope (SEM). The product yield was optimized with different pH levels and the maximum yield was obtained at 32.5 % at pH 10.96. The moisture, and ash content of the extracted product was measured and found at 13.25 % and 4.35 %, respectively. The viscosity of the extracted product was obtained at 60.1 mPs. The UV–visible spectrophotometry showed different absorbance peaks found at 234 nm, 240 nm, 250 nm, and 264 nm which assigned the extracted product of sodium alginate, and the maximum absorption peak lies at 276.7 nm which assigned flavonoids, and their derivatives of alginates. The fluorescence spectrophotometry demonstrated a strong emission peak at 460 nm with higher intensity (200), indicating the presence of sodium alginate. The FTIR showed the characteristic peaks that demonstrated different functional groups of sodium alginate. The XRD pattern demonstrated 0.24 crystalline indexes indicating the semi-crystalline product in nature. SEM showed clear fibrils of sodium alginate morphology indicating the absence of impurity materials.

All‐Weather Self‐Powered Intelligent Traffic Monitoring System Based on a Conjunction of Self‐Healable Piezoresistive Sensors and Triboelectric Nanogenerators

AbstractA self‐powered and sustainable traffic monitoring system is highly required for future urban development. Herein, self‐healable piezoresistive sensors and triboelectric nanogenerators (TENGs) are constructed by in situ polymerization of polyvinyl alcohol‐polyacrylamide double network hydrogel in the presence of sodium alginate and tannic acid‐modified cellulose nanocrystals (denoted as PPC) for all‐weather self‐powered intelligent traffic monitoring applications. Because of hydrogen bonding and boron ester bonding, the resultant PPC‐based strain sensor can rapidly self‐heal and restore its sensing ability within 1 min with a self‐healing efficiency of 97.4%. Based on piezoresistive effect, the ions in sodium alginate endow the PPC‐based strain sensor with a relatively high gauge factor of 8.39, which can monitor the motion and fatigue of drivers. Based on triboelectrification effect, the PPC‐based TENG sensor can detect instantaneous vehicle speed, judge traffic accident liability, evaluate vehicle weight, and alert the driver to prevent accidents caused by drowsy driving. After partially replacing water in the PPC with glycerin, the resulting PPC‐based TENG sensor exhibits stable performance at temperatures ranging from ‐30 to 40 °C, ensuring its all‐weather monitoring ability. The all‐weather and self‐powered intelligent traffic monitoring system is promising for ensuring the security of future cities.

Ice recrystallization inhibition and acceleration by cellulose nanocrystals in the presence of anionic and neutral polymers

Understanding mixed stabilizers' ice recrystallization inhibition (IRI) effect is important for ice cream formulation. The IRI effect of cellulose nanocrystals (CNCs) was investigated in the presence of sodium alginate (SA), carboxymethyl cellulose (CMC), polyethylene glycol (PEG), and inulin. Adding low concentrations of SA (≤0.13%) and CMC (≤0.05%) enhanced the IRI effect of CNCs. The enhancement became less at higher concentrations of SA and CMC. Recrystallization was even accelerated with a further increase in concentration of SA (≥0.5%) or CMC (≥0.2%). PEG and inulin had little influence on the IRI effect of CNCs. Rheological analysis of polymer overlap concentration, particle size analysis of CNCs dispersion, and microscopical observation of ice crystals accretion suggested that the dual effects of excluded volume might explain the IRI effect of CNCs in the presence of polymers: (1) adding polymers resulted in the macromolecular crowding, reducing the available volume for CNCs and increasing their effective concentration to interact with ice crystals, and led to an enhanced IRI effect; (2) depletion interaction promoted the aggregation of CNCs and merging of ice crystals, resulting in less enhancement and recrystallization acceleration. Our findings advance our understanding of the IRI effect for mixed stabilizers and are critical to ice cream formulation.

Nanocomposite Hydrogel Films Based on Sequential Interpenetrating Polymeric Networks as Drug Delivery Platforms.

In this study, novel materials have been obtained via a dual covalent and ionic crosslinking strategies, leading to the formation of a fully interpenetrated polymeric network with remarkable mechanical performances as drug delivery platforms for dermal patches. The polymeric network was obtained by the free-radical photopolymerization of N-vinylpyrrolidone using tri(ethylene glycol) divinyl ether as crosslinker in the presence of sodium alginate (1%, weight%). The ionic crosslinking was achieved by the addition of Zn2+, ions which were coordinated by the alginate chains. Bentonite nanoclay was incorporated in hydrogel formulations to capitalize on its mechanical reinforcement and adsorptive capacity. TiO2 and ZnO nanoparticles were also included in two of the samples to evaluate their influence on the morphology, mechanical properties and/or the antimicrobial activity of the hydrogels. The double-crosslinked nanocomposite hydrogels presented a good tensile resistance (1.5 MPa at 70% strain) and compression resistance (12.5 MPa at a strain of 70%). Nafcillin was loaded into nanocomposite hydrogel films with a loading efficiency of up to 30%. The drug release characteristics were evaluated, and the profile was fitted by mathematical models that describe the physical processes taking place during the drug transfer from the polymer to a PBS (phosphate-buffered saline) solution. Depending on the design of the polymeric network and the nanofillers included, it was demonstrated that the nafcillin loaded into the nanocomposite hydrogel films ensured a high to moderate activity against S. aureus and S. pyogenes and no activity against E. coli. Furthermore, it was demonstrated that the presence of zinc ions in these polymeric matrices can be correlated with the inactivation of E. coli.

Eco-friendly Synthesis of Hydrogel Nano-composites for Removal of Pollutants as a Model Rose Bengal Dye

In this study, hydrogel Nano-composite was prepared by free radical polymerization in the presence of sodium alginate (SA) and TiO2 nanoparticles (TiO2 NPS) as a surface catalyst. Potassium per sulfate (KPS) was used as a reaction initiator. Crosslinking agent methylene bis-acrylamide, the structure and morphology its hydrogel Nano-composites were studied using Transmission electron microscopy (TEM), X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDX), and Field emission scanning electron microscopy (FE-SEM). Several factors that affected the adsorption process were studied, including effect of pH, effect of salt concentration and temperature. Also studied was the swelling behavior in two acidic mediums (pH=7, pH=1.2), the best surface swelling medium was at (pH=7). The adsorption isotherms were studied, and the result obeyed as favorable by Fruendlich isotherm depended on the value of (R2= 0.9404).

Bio-based material formulation for extrusion printing by dityrosine crosslinking of unmodified casein

In the development of new functional bio-based materials in the field of three-dimensional (3D) printing, visible light-induced dityrosine crosslinking gains increasing interest. In this context, most current bio-based materials and ink formulations rely on previously modified chemical substances with increased tyrosine availability. In contrast, we developed and characterized a photopolymerizable ink formulation for extrusion printing based on the unmodified and naturally occurring protein casein. Manufacturability of formulations containing protein, photoinitiating system, buffer and a thickening agent turned out to be a key factor for the ink development. In total, eight different thickening agents were assessed regarding their suitability to increase the viscosity of the ink formulation to expand the fabrication window for extrusion-based 3D printing. The mechanical properties of the ink formulation and hydrogel in presence of sodium alginate were further characterized and the macroscopic fabrication of auxetic structures consisting of up to 30 layers was achieved by applying extrusion-based printing.

Biomimetic mineralization and characterization of hierarchically structured hydrated magnesium carbonates: The effects of sodium alginate

Recently, CO2 mineralization involving magnesium salt provides a feasible way for carbon sequestration. The produced hydrated magnesium carbonates (HMCs) can be used as functional materials and will bring huge economic benefits. Inspired by the mineralization in biological organisms, the indirect CO2 mineralization process involving NH4HCO3-MgCl2 in the presence of sodium alginate (SA) was systematically investigated. XRD, SEM, FTIR, TG and XPS were used to characterize the crystal phase, morphology, structure and surface of HMCs. By the regulation of temperature, HMCs with a complex hierarchical structure were successfully synthesized, i.e., sea urchin-like nesquehonite assembled by nanorods and 3D spiderweb-like hydromagnesite assembled by nanosheets. The presence of SA inhibits the phase transition from nesquehonite to hydromagnesite, and the inhibitory effect increases as the concentration of SA increases. By decreasing the molar ratio of Mg2+/HCO3−, the shape of nesquehonite particle changes from a sphere to an ellipsoid or a gourd. The spherical structure of nesquehonite is destroyed in a weak alkaline solution and the crystalline product is flower-like hydromagnesite in a strong alkaline solution. The decomposition process of HMCs is composed of dehydration (or dehydration and dehydroxylation) stage and decarbonation stage. XPS results for nesquehonite and hydromagnesite are quite different due to their different surface structure. This study will provide insights into the preparation of hierarchically structured HMCs by indirect CO2 mineralization and promote added values of HMCs by biomimetic mineralization method.

Preparation of sustainable activated carbon-alginate beads impregnated with ionic liquid for phenol decontamination

Powder activated carbon (PAC), derived from calligonum pollygonides, was successfully modified with the ionic liquid (IL) trihexyltetradecylphosphonium bromide ([PC6C6C6C14][Br]) in the presence of sodium alginate and characterized using SEM, FTIR and TGA. PAC, granular AC (GAC), AC-alginate and AC-Alg-IL bead were assessed for the removal of phenol from aqueous media via batch adsorption. Both PAC and AC-Alg-IL beads displayed high adsorption capacities, 123 mg/g and 78 mg/g, respectively, under optimized conditions. In contrast, GAC gave a much lower adsorption capacity than AC-ALG-IL beads, indicating that AC-ALG-IL beads are superior as potential adsorbents for this industrial application. Theoretical studies showed that the pseudo-second-order kinetic and Freundlich isotherm models were suitable to describe the adsorption process. The interaction between phenol and AC-Alg-IL beads was analyzed using the conductor-like screening model for realistic solvents (COSMO-RS). It has been concluded that AC-Alg-IL beads can be used as an efficient adsorbent for phenol and other organic compounds.

Experimental study on the separation of quartz from pyrite using alginate as a selective depressant substantiated by theoretical analysis on intermolecular bonding

The surface chemical properties of quartz containing iron species and pyrite in the presence of sodium alginate (ALG) as well as bulk solution studies of Fe were experimentally and theoretically investigated. The adsorption of ALG onto pyrite and quartz containing iron species was observed to decrease with increase in pH. The binding energy calculations at BP86/6-311++g/def2-TZVP level of theory indicated that the most stable structure for Si(OH)5-∙∙∙ FeOH+∙∙∙ALG complex had a complexation energy of −834.5 kJ/mol on the singlet (S = 0) potential energy hypersurface. Additionally, FeOH+∙∙∙ALG and Si(OH)5-∙∙∙FeOH+ complexes were the most stable on the quintet (S = 2) potential energy hypersurface with complexation energies of −2352.9 and −1596.4 kJ/mol, respectively. The nature of interaction in the complexes was further probed by using various quantum chemical tools namely quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analysis. The results indicated that the interactions OFe∙∙∙O in FeOH+∙∙∙ALG and Si(OH)5-∙∙∙FeOH+ as well as OH∙∙∙O hydrogen bond in Si(OH)5-∙∙∙FeOH+∙∙∙ALG were partially covalent in nature. In the presence of 2000 g/t of ALG at pH 5.3, the grade and recovery of Fe obtained was 44.7% and 97.2% with a selectivity index of 35.8.

Eco-friendly rapid removal of palladium from aqueous solutions using alginate-diatomite magnano composite

The aim of this study was to evaluate the feasibility of magnetic polymer imprinted diatomite composite (MPIDC) to remove of palladium from aqueous solutions. The chemical co-precipitation method was used to synthesis of MPIDC. The obtained results from study of the MPIDC adsorbent characterization, indicated the presence of sodium alginate, diatomite and Fe3O4 in the MPIDC structure.The BJH desorption cumulative pore volume, the average pore size of the sample and the BET specific surface area were 1.343 cm3g−1, 24.605 nm and 63.44 m2g−1, respectively. Modeling studies were done using R software based on response surface methodology (RSM). The ANOVA analysis was used in order to determine the best-fit model. Based on the results obtained from ANOVA analysis, the second-order model (SO), indicated a satisfactory adjustment with experimental data. The solver method was applied for optimization study. Based on the results obtained from solver method, the maximum adsorption performance of 90.04% (involving all parameters simultaneously) was achieved at pH of 5.45; initial palladium concentration of 15.13 mg L−1; contact time of 104.8 min and MPIDC dosage of 0.98 g L−1. The statistical terms including coefficient of determination (R2), root mean square error (RMSE), chi-square statistic (X2), average percentage error (APE) and residual sum of squares (RSS) were used in order to determine the best-fit isotherm and kinetic models. Investigation of statistical results revealed the good agreement of experimental data with three- parameter nonlinear Sips model. Therefore, adsorption of palladium onto MPIDC, at high concentration is related to Langmuir model, whereas the adsorption process at the low concentrations of palladium implies from Freundlich model. Based on the Sips model, maximum adsorption capacity of MPIDC was calculated 60.2 mg g−1. With comparison of the nonlinear kinetic models, pseudo-second-order was found to agree well with the experimental data. It reveals adsorption of palladium molecules onto sorption sites on the adsorbent surface is based on a chemical adsorption.The thermodynamic data revealed the exothermic nature and spontaneous sorption for the adsorption of palladium onto MPIDC.

The adsorption behaviour of triclosan onto magnetic bio polymer beads impregnated with diatomite

ABSTRACT The decrement rate of triclosan (TCS) in aqueous solutions was investigated by adsorption onto alginate beads impregnated with magnetic diatomite (ABMD). The obtained results from the study of the ABMD adsorbent characterisation indicated the presence of sodium alginate, diatomite and Fe3O4 in the ABMD structure. The optimisation of data was done by the response surface methodology using R software. The second-order model was selected as the appropriate model (because of lack of fit ˃ 0.05 and also the higher R 2 than the other models). The parameters of (pH, time and ABMD dosage) and (initial TCS concentration) indicated intensifying and reducing effects on the TCS adsorption onto ABMD, respectively. According to the obtained results from solver analysis, the maximum TCS removal (94.47) was achieved at pH of 9.18; initial TCS concentration of 3.54 mg L−1; contact time of 58.84 min and ABMD dosage of 0.15 g L−1. The TCS adsorption experimental data were good fitted with Khan model. The maximum adsorption rate of TCS per mass unit of ABMD was 2.9 mg g−1 (calculated by the Khan model). The pseudo-second-order model was found to agree well with the adsorption experimental data obtained for TCS.

Nanocomposite hydrogel based on sodium alginate, poly (acrylic acid), and tetraamminecopper (II) sulfate as an efficient dye adsorbent

In this study, a novel nanocomposite hydrogel (NCH) was prepared by in situ crosslinking and radical polymerization of acrylic acid (AA) in the presence of sodium alginate (Na-Alg), followed by loading of Cu2+ ions and reaction with ammonia. The main advantage of the synthesized NCH is the high adsorption of dye due to the large contact area. The structure of the NCH was studied by FT-IR spectroscopy, TEM, and SEM. TEM showed that the size of nanoparticles is about 5–30 nm. The adsorption of dye was studied by changing the different factors. The removal efficiency of Crystal Violet (CV) and Malachite Green (MG) was found to be more than 96% at concentration of 10 mg/L and pH = 6. The dye adsorption on the NCH is well described by Freundlich isotherm and pseudo-second-order kinetic models. The reusability experiments showed that about 95% of the initial adsorption was obtained after eight cycles.

Effects of nanoselenium as a nutrient medium component on the main cultivation parameters and antagonistic activity of <i>Lactobacillus</i> strains

The study aims to establish the effect of nanoselenium on the growth and antagonistic activity of the Lactobacillus casei IMB B-7343 and Lactobacillus plantarum IMB B-7344 strains against the phytopathogenic bacterium Xanthomonas campestris B-4102. Selenium nanoparticles were obtained by reducing a solution of sodium selenite with L-cysteine in the presence of sodium alginate. The cultivation of Lactobacilliwas carried out in a MRS nutrient medium with the addition of a colloidal solution of nanoselenium at the following concentrations: 0.05; 0.1; 0.15; 0.2 and 0.25 mg/l (for selenium). Bacteria were cultured in a 96-well plate in a Multiskan FC photometer at 36 ºС under constant shaking. The antagonistic activity of the strains was studied by the method of agar blocks. It was found that the addition of nanoselenium to the nutrient medium at a concentration of 0.2 to 0.25 mg/l contributed to a decrease in the duration of the exponential growth phase by an average of 3 hours, as well as to a decrease in the biomass accumulation of the L. casei IMB B-7343 strain by 15.0%. The optical density of this strain culture was observed to increase by 15.9% in the stationary growth phase under the addition of a nanoselenium solution to the nutrient medium at a concentration of 0.15 mg/l. During the cultivation of the L. plantarum IMB B-7344 strain in an MRS nutrient medium with the addition of a colloidal solution of nanoselenium at a concentration of 0.05–0.25 mg/l in the exponential development phase, an acceleration of the culture growth on average by 5 hours relative to the control was observed. It was noted that, upon the addition of nanoselenium to the nutrient medium, an increase in the antagonistic activity of lactobacillus strains against the phytopathogenic bacterium X. campestris B-4102 was observed, particularly in the L. plantarum IMB B-7344 strain (the zone of inhibition of the phytopathogen growth was 14.5–15 mm).

Strong anti-polyelectrolyte zwitterionic hydrogels with superior self-recovery, tunable surface friction, conductivity, and antifreezing properties

Salt-responsive hydrogels, have great potential in electrochemical devices and marine-related applications. But so far most of these hydrogels swell in water while shrink in salt solution. Herein, based on a special zwitterionic monomer, 3-(1-(4-vinylbenzyl)-1H-imidazol-3-ium-3-yl)propane-1-sulfonate (VBIPS), tough double-network hydrogels showing strong anti-polyelectrolyte effect were designed. The hydrogel was prepared by one-pot copolymerization of VBIPS and N-(2-Hydroxyethyl) acrylamide in the presence of sodium alginate. The double-network showed good mechanical properties and excellent recoverability. These hydrogels with salt-response exhibited shrinkage, opaque, and high surface friction in water, but swelled, camouflage, and high lubrication in salt solution. Meanwhile, after complexing with multivalent cations, the hydrogels not only maintained the initial flexibility, but also largely decreased the freezing point to −60 °C. Besides, the interesting electrochemical behavior of polyzwitterions offered the hydrogels showing high ionic conductivity both at room temperature and ultra-low temperature, which greatly broadened the applications to extreme conditions.

Alginate as Dispersing Agent for Compounding Natural Rubber with High Loading Microfibrillated Cellulose.

Natural rubber (NR) reinforced with high loading of microfibrillated cellulose (MFC) was fabricated in the presence of sodium alginate as a thickening and dispersing agent in NR latex. The tensile strength and Young’s moduli of the 50% wt. MFC loading-NR composites were 13.6 and 1085.7 MPa, which were about 11.3- and 329-times enhanced compared with those of the neat NR film. The maximum elongation at 313.3% was obtained from 30% MFC loading, which was a 3.3-fold increase of that of the NR film. The thermal stability of MFC–NR films was slightly reduced, while the glass transition temperature remained unchanged at −64 °C. The MFC–NR films exhibited high water adsorption ability, toluene resistance, and biodegradability.

Electrochemical reduction of Cr(VI) in the presence of sodium alginate and its application in water purification

Chromium (Cr) is used in many manufacturing processes, and its release into natural waters is a major environmental problem today. Low concentrations of Cr(VI) are toxic to human health and living organisms due to the carcinogenic and mutagenic nature of this mineral. This work examined the conversion of Cr(VI) to Cr(III) via electrochemical reduction using gold electrode in an acidic sodium alginate (SA) solution and subsequent removal of the produced Cr(III)-SA by the polymer-enhanced ultrafiltration (PEUF) technique. A solution of SA in nitric acid was used both as an electrolytic medium during the voltammetric measurements and bulk electrolysis and as an extracting agent during the PEUF technique. The electroanalysis of Cr(VI) was performed by linear sweep voltammetry in the presence of acidic SA solution to study its voltammetric behavior as a function of the Cr(VI) concentration, pH, presence of Cr(III), SA concentration and scan rate. In addition, the quantitative reduction of Cr(VI) to Cr(III) was studied through the bulk electrolysis technique.The results showed efficient reduction with well-defined peaks at approximately 0.3 V vs. Ag/AgCl, using a gold working electrode. As the pH increased, the reduction signal strongly decreased until its disappearance. The optimum SA concentration was 10 mmol/L, and it was observed that the presence of Cr(III) did not interfere in the Cr(VI) electroanalysis. Through the quantitative reduction by bulk electrolysis in the presence of acidic SA solution, it was possible to reduce all Cr(VI) to Cr(III) followed by its removal via PEUF.

Effects of sodium alginate on microstructural and properties of bacterial cellulose nanocrystal stabilized emulsions

In this work, we reported the in situ biological modification of bacterial cellulose (BC) using various sodium alginate with different molecular weights as the carbon source in the fermentation media. The presence of sodium alginate (SA) showed a great influence on the microstructure of the resulting components of bacterial cellulose incorporated with sodium alginate (SA-BCs), based on the characterization results of SEM images, FT-IR analysis, crystallinity index, and contact angles. With the addition of high molecular weight of SA, the resulting high molecular weight of SA and BC composite (H-SA-BC) demonstrated a narrower fiber and less intramolecular hydrogen bonds, as compared to the modified BCs with lower molecular weights. Specifically, the crystallinity index value of SA-BCs was observed to decrease with the increase of SA’s molecular weight. Using these SA-BCs as emulsifiers, the corresponding physicochemical properties and emulsifying performances of BC and SA-BCs in the stabilization of olive oil Pickering emulsion were fully assessed by Optical micrographs, the diameter of droplets and CLSM images. SA-BCs were proven to show stronger amphipathicity as compared to BC due to the lower molecular regularity of SA-BC and the presence of carboxyl groups. The droplets of the emulsions are observed to be smaller and more uniform when stabilized by the emulsifier of H-SA-BC. Therefore, the addition of SA in the biological modification of BC resulted in a great change in both morphology and amphiphilicity. These results would be helpful in the understanding of the development of natural materials as stabilizers for the potential applications of Pickering emulsions.

The effect of alginates on the hydration of calcium aluminate cement

The hydration of calcium aluminate cement (CAC) in the presence of sodium alginate which is known to slightly retard Portland cement, was studied using heat flow calorimetry and mortar strength testing. Most surprisingly, addition of alginate resulted in an earlier occurrence of the maximal heat release as well as an increased early strength, thus confirming that in CAC alginate acts as accelerator. The thickening effect of alginate was effectively compensated using a superplasticizer while retaining its accelerating property. An investigation of the pore solution composition indicated that in the presence of alginate the concentration of calcium ions was reduced. Such effect normally causes retardation of cement hydration and should delay the formation of C-A-H phases. Apparently, the strong calcium ion complexing ability of alginate promotes the formation of C-A-H via e.g. a templating effect. A combined application of alginates and lithium salts presents a viable option to reduce the lithium consumption in CAC acceleration.

An eco-friendly and effective flame retardant coating for cotton fabric based on phytic acid doped silica sol approach

The high flammability of cellulosic materials somewhat limits their practical application. The introduction of an environmentally benign flame retardant coating for cotton fabric was achieved by hydrolyzing tetraethoxysilane and doping the silica sol with phytic acid in the presence of sodium alginate. The hybrid silica sol had high condensation degree and the modified silica particles had a spherical structure. The coated cotton fabrics with the hybrid PA/silica sol systems showed enhanced thermal stability at high temperatures, and displayed significantly suppressed heat and smoke generation ability, compared with the uncoated one. The hybrid silica sol coatings influenced the combustion performance of cotton via a charring action, and endowed the cotton fabrics with self-extinguishing ability during the vertical flammability test, demonstrating the improvement in fire resistance. The coated cotton fabrics displayed enhanced char yields, whilst maintained their texture structures after burning. Besides, the silicon- and phosphorus-containing components were also found to have a synergistic flame retardant action on cotton.

Tough, stretchable and compressive alginate-based hydrogels achieved by non-covalent interactions.

In this study, two alginate-based hydrogels with good mechanical strength, toughness and resilience were synthesized by hydrophobic interaction and coordination bonding. Sodium alginate/poly(acrylamide) semi-interpenetrating network (NaAlg/PAM semi-IPN) hydrogels were first synthesized through the micelle copolymerization of acrylamide and stearyl methacrylate in the presence of sodium alginate, then calcium alginate/poly(acrylamide) double network (CaAlg/PAM DN) hydrogels were prepared by immersing the as-prepared NaAlg/PAM semi-IPN hydrogels in a CaCl2 solution. FT-IR and XPS results revealed NaAlg/PAM semi-IPN hydrogels and CaAlg/PAM DN hydrogels were successfully synthesized through non-covalent interactions. The tensile strength of CaAlg/PAM DN hydrogels could reach 733.6 kPa, and their compressive strengths at 80% strain are significantly higher than those of the corresponding NaAlg/PAM semi-IPN hydrogels, which is attributed to the alginate network crosslinked by Ca2+. The dual physically crosslinked CaAlg/PAM DN hydrogels can achieve fast self-recovery, and good fatigue resistance, which is mainly assigned to energy dissipation through dynamic reversible non-covalent interactions in both networks. The self-healing ability, swelling behavior and morphology of the synthesized alginate-based hydrogels were also evaluated. This study offers a new avenue to design and construct hydrogels with high mechanical strength, high toughness and fast self-recovery properties, which broadens the current research and application of hydrogels.