As-prepared Composite Hydrogel Research Articles

A convenient swelling-permeation strategy for constructing high-performance fiber reinforced composite hydrogel

Ligaments are a unique wet biological tissue with ultrahigh tensile strength, modulus, and flexural flexibility. Developing artificial materials with similar properties is important but challenging. Herein, we present a novel swelling-permeation strategy for preparing high-performance fiber reinforced composite hydrogels capable of mimicking the ligaments. Through pre-swelling the meta-aramid fibers in good solvents to vastly boost their porosity, large amounts of pre-gel solution can permeate into the pores of fibers during the soaking process. After the polymerization of pre-gel solutions inside and around fibers, the interpenetrating networks form directly between the hydrogel matrix and meta-aramid fibers. The mechanical interlock and abundant hydrogen bond of interpenetrating networks enable the generation of strong interfacial binding between hydrogels and fibers. In consequence, the as-prepared composite hydrogel has high tear resistance (405.30 kJ/m2), tensile strength (125 MPa), and modulus (218 MPa), superior to previously reported composite hydrogels. Meanwhile, the resulting composite hydrogels have outstanding flexibility and good biocompatibility, thereby exhibiting great potential as artificial ligaments. The preparation method proposed in this paper is simple, controllable, and scalable, which opens up the possibility of large-scale production of artificial ligaments.

Polypropylene mesh coated with hyaluronic acid/polyvinyl alcohol composite hydrogel for preventing bowel adhesion

Polypropylene (PP) mesh is the most widely used prosthetic material in hernia repair. However, the efficacy of implanted PP mesh is often compromised by adhesion between viscera and PP mesh. Thus, there is a recognized need for developing an anti-adhesive PP mesh. Here, a composite hydrogel coated PP mesh with the prevention of adhesion after hernia repair was designed. The composite hydrogel coating was prepared from polyvinyl alcohol (PVA) and hyaluronic acid (HA) by using the freezing-thawing (FT) method. To overcome the shortcoming of the long time of the traditional freezing-thawing method, a small molecule 3,4-dihydroxyphenylacetic acid (DHPA) was introduced to promote the formation of composite hydrogel. The as-prepared composite hydrogel coating displayed modulus more closely resembling that of native abdominal wall tissue. In vitro studies illustrated that the resulting meshes showed excellent coating stability, hemocompatibility, and non-cytotoxicity. In vivo experiments using a rat abdominal wall defect model demonstrated that the composite hydrogel coated PP mesh could prevent the formation of adhesion, alleviate the inflammatory response, and reduce the deposition of collagen around the damaged tissue. These disclosed results manifested that the PP mesh coated with HA/PVA composite hydrogel might be a promising application in preventing adhesion for hernia repair.

CuS nanotube/chitin composite hydrogel with enhanced photothermal efficiency for near-infrared-activated bacteria-killing

The research on biocompatible materials which exhibit remarkable antibacterial capability has always attracted lots of interests. Among numerous antibacterial materials, CuS micro-/nanomaterial has gained attention as a promising option due to its low toxicity and efficiently photothermal effect. In this study, CuS nanotube/chitin composite hydrogel was prepared by crosslinking with chitin. Due to the prominent photothermal conversion efficiency of CuS nanotube which was up to 64.3 %, the as-prepared composite hydrogel showed enhanced photothermal effect under near-infrared (NIR) illumination. The composite hydrogel also showed a typical peroxidase-like activity which can convert H2O2 into an extremely oxidative and toxic hydroxyl radicals (•OH). The prominent photothermal effect and peroxidase-like activity made the composite hydrogel perform well in antibacterial against Escherichia coli with NIR activation. The possible mechanism of NIR-activated antibacterial from CuS nanotube/chitin composite hydrogel was discussed as well. The results of this work indicate that the CuS/chitin composite hydrogel with enhanced photothermal effect could be a new NIR-activated antibacterial agent used for sterilization.

Mechanically robust hydrogel from thermosetting polybenzoxazine with dual crosslinking network

The main chain of polymer composition in hydrogels is mostly aliphatic and the crosslinking density is usually low, which renders the hydrogels with low mechanical strength. In this work, a kind of thermosetting resin, benzoxazine is used as the starting material to prepare the corresponding hydrogels by one-pot synthesis. The organic gels are firstly formed in dimethylformamide with the aid of catalyst, followed by extraction of water to give the hydrogels. It is revealed that due to the presence of covalent crosslinking and abundant hydrogen bonding, the as-prepared rigid hydrogels show extremely high compressive strength. The hydrogel with 55.8 wt% of water shows yield strength about 20 MPa and sustains compressive strength of 75 MPa (compressive stress of 30 kN, compressive strain of 67 %) without cracking. The hydrogel also show extremely high dielectric constant of 392,000, dielectric loss of 971,000, and ionic conductivity of 1.7 × 10−3 S/m at 100 Hz. Moreover, the responsiveness to pH variation suggests its potential application as smart responsive materials. To show the superiority of preparing functional composite hydrogels using this strategy, electroconductive and magnetic fillers are introduced and the as-prepared composite hydrogels show good electromagnetic shielding performance.

Establishing a Corrugated Carbon Network with a Crack Structure in a Hydrogel for Improving Sensing Performance.

Electronic conductive hydrogels have prompted immense research interest as flexible sensing materials. However, establishing a continuous electronic conductive network within a hydrogel is still highly challenging. Herein, we develop a new strategy to establish a continuous corrugated carbon network within a hydrogel by embedding carbonized crepe paper into the hydrogel with its corrugations perpendicular to the stretching direction using a casting technique. The corrugated carbon network within the as-prepared composite hydrogel serves as a rigid conductive network to simultaneously improve the tensile strength and conductivity of the composite hydrogel. The composite hydrogel also generates a crack structure when it is stretched, enabling the composite hydrogel to show ultrahigh sensitivity (gauge factor = 59.7 and 114 at strain ranges of 0-60 and 60-100%, respectively). The composite hydrogel also shows an ultralow detection limit of 0.1%, an ultrafast response/recovery time of 75/95 ms, and good stability and durability (5000 cycles at 10% strain) when used as a resistive strain sensing material. Moreover, the good stretchability, adhesiveness, and self-healing ability of the hydrogel were also effectively retained after the corrugated carbon network was introduced into the hydrogel. Because of its outstanding sensing performance, the composite hydrogel has potential applications in sensing various human activities, including accurately recording subtle variations in wrist pulse waves and small-/large-scale complex human activities. Our work provides a new approach to develop economical, environmentally friendly, and reliable electronic conductive hydrogels with ultrahigh sensing performance for the future development of electronic skin and wearable devices.

Developing a carbon composite hydrogel with a highly conductive network to improve strain sensing performance

Both carbon aerogels and conductive hydrogels have provoked immense research interest as flexible sensing materials. However, conventional carbon aerogels show limited stretchability, while conductive hydrogels generally show limited conductivity. Herein, we develop a carbon composite hydrogel with a highly conductive network by encapsulating a cellulose fiber-derived carbon aerogel with a liquid metal-based conductive hydrogel formed by the in situ free radical polymerization of acrylic acid. The as-prepared carbon composite hydrogel inherits its high conductivity from the cellulose fiber-derived carbon aerogel and its good stretchability, adhesion and self-healing properties from the liquid metal-based hydrogel. Moreover, the carbon composite hydrogel possesses a high tensile strength and toughness due to the rigid network of the carbon aerogel. When serving as the tensile strain sensing material, the carbon composite hydrogel shows a very high sensitivity (gauge factor = 13.1 in the strain range of 400–500%), ultralow detection limit (0.1%), quick response and recovery time (166 ms at the strain of 1%) and excellent durability (1000 cycles under at 10% and 100% strains). In addition, the carbon composite hydrogel can obtain good temperature tolerance, adapt to high humidity and sustain its good sensing performance at low and high temperatures simply by coating a layer of glycerin on its surface. This work broadens the prospects for the design and preparation of conductive hydrogel-based strain sensors, and it facilitates their application in monitoring the biomedical signals of humans.

Antibacterial Gelatin Composite Hydrogels Comprised of In Situ Formed Zinc Oxide Nanoparticles.

We report the feasibility of using gelatin hydrogel networks as the host for the in situ, environmentally friendly formation of well-dispersed zinc oxide nanoparticles (ZnONPs) and the evaluation of the antibacterial activity of the as-prepared composite hydrogels. The resulting composite hydrogels displayed remarkable biocompatibility and antibacterial activity as compared to those in previous studies, primarily attributed to the uniform distribution of the ZnONPs with sizes smaller than 15 nm within the hydrogel network. In addition, the composite hydrogels exhibited better thermal stability and mechanical properties as well as lower swelling ratios compared to the unloaded counterpart, which could be attributed to the non-covalent interactions between the in situ formed ZnONPs and polypeptide chains. The presence of ZnONPs contributed to the disruption of bacterial cell membranes, the alteration of DNA molecules, and the subsequent release of reactive oxygen species within the bacterial cells. This chain of events culminated in bacterial cell lysis and DNA fragmentation. This research underscores the potential benefits of incorporating antibacterial agents into hydrogels and highlights the significance of preparing antimicrobial agents within gel networks.

Regenerated silk fibroin and alginate composite hydrogel dressings loaded with curcumin nanoparticles for bacterial-infected wound closure

It is important to treat a bacterial-infected wound with a hydrogel dressing due to its excellent biocompatibility and extracellular matrix mimicking structure. In this work, the antibacterial curcumin nanoparticles (Cur-NPs) loaded silk fibroin and sodium alginate (SF/SA) composite hydrogels have been developed as dressings for bacterial-infected wound closure. The as-prepared composite hydrogel dressings exhibited excellent biocompatibility and antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in vitro. In addition, the composite hydrogel dressings showed good tissue adhesive strength because of their high viscosity and abundance of amino groups distributed on SF, which can form multi-aldehyde polysaccharides with the tissue surface. The porous 3D structure of the composite hydrogel dressings facilitated the absorption of exudate from the wound site and promoted the fusion of cellular nutrients and metabolites. In the full-thickness skin defect model with and without bacterial infection, the Cur-NPs loaded SF/SA composite hydrogel dressings prominently improves the closure of bacterial-infected wounds by improving cell proliferation, anti-inflammatory properties, vascular remodeling, and collagen deposition.

Mechanoresponsive ionic elastomers with Ultra-Stretchability, high toughness, fatigue resistance, and extreme temperature resistance

In the development of elastic materials, the non-synergy between stretchability and toughness is a challenge. Herein, we propose a rational design of a composite hydrogel by introducing strongly polarized hydrated Li-ion clusters, electron-withdrawing carboxyl groups, and Sn(II) complexation into hydrogen-bonded poly(acrylamide) (PAM) network. Weak interaction between Li-ions and amide groups facilitates the rapid flipping and slipping of the PAM chains during stretching, optimizing the stretchability of the hydrogel. This composite also provides an energy-dispersing mechanism based on strong ionic complexation between Sn(II) and amide groups, which improves its toughness. As-prepared composite hydrogel simultaneously exhibits high stretchability (>7000% elongation), ultra toughness of 580 kPa, excellent fatigue resistance and extreme temperature resistance (elastic at − 60 and 70 °C). Due to its excellent comprehensive performances, the present soft material has broad application prospects in agriculture, medicine, construction, and machinery.

Ionic liquid decorated MXene/Poly (N-isopropylacrylamide) composite hydrogel with high strength, chemical stability and strong adsorption

Organic phenolic pollutants in industrial wastewater cause severe environmental pollution and physiological damage. Poly (N-isopropylacrylamide) (PNIPAM) hydrogels generally have poor mechanical strength and are also intrinsically frangible, limiting their widespread applications in wastewater treatment. Combining them with 2-dimensional materials can also only improve the mechanical properties of hydrogels. Here, we report a high-strength, chemical stability and strong adsorption MXene/poly (N-isopropylacrylamide) (PNIPAM) thermosensitive composite hydrogel for efficient removal of phenolic pollutants from industrial wastewater. Ionic liquids (ILs) were grafted onto the surface of MXenes and introduced into NIPAM monomer solution to obtain composite hydrogels by in-situ polymerization for improved mechanical strength and adsorption capacity of the composite hydrogel. Compared with the MXene/PNIPAM composite hydrogel, the introduction of ILs simultaneously improves the mechanical and adsorption properties of the composite hydrogel. The ILs bind to the surface of MXene flakes through electrostatic interactions, which improved the thermal stability and oxidation resistance of MXenes while maintaining its good dispersion. Using 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) modified MXene (MXene-EMIMBF4) did not change significantly were observed after aging for 45 days. As-prepared composite hydrogels demonstrated excellent mechanical properties, reusability, and high adsorption capacity for p-Nitrophenol (4-NP). The MXene-EMIMBF4/PNIPAM hydrogel could recover after ten 95% strain compression cycles under the synergistic effect of chemical bonding and electrostatic attraction. Its maximum adsorption capacity for 4-NP was 200.29mgg-1 at room temperature, and the adsorption capacity maintained at ∼90% of its initial value after five adsorption cycles, which was related to the introduction of EMIMBF4 to form a denser network structure. The adsorption data followed the pseudo-second-order kinetics and Freundlich models.

Anisotropic and robust hydrogels combined osteogenic and angiogenic activity as artificial periosteum

Periosteum possesses unique characteristics such as anisotropic structure and superior osteogenic and angiogenic ability, which plays vital roles in the formation, remodeling and fracture repair of bone. However, the development of artificial periosteum with such highly desired characteristics is still a challenge. Here, we exhibit the strong and anisotropic chitin composite hydrogels that are composed of chitin chains and maleation chitin whiskers (mCHWs) via chemical and physical dual cross-linking strategy and the stretching-drying process. Moreover, bioactive deferoxamine (DFO) was chosen to further functionalize this anisotropic composite hydrogel to strengthen its ability of osteogenesis and vascularization. This design endows the as-prepared composite hydrogels with remarkable tensile strength (17.6 ± 1.4 MPa) and Young's modulus (28.1 ± 2.2 MPa), which are obviously superior to those of polysaccharide hydrogels according to the most references. More importantly, such composite hydrogels not only can effectively enhance cells adhesion and proliferation, but also have the outstanding capability to facilitate the osteogenesis and angiogenesis of cells. Thus, these anisotropic and robust chitin composite hydrogels show promising application for the artificial periosteum.

Chitosan-reinforced PHB hydrogel and aerogel monoliths fabricated by phase separation with the solvent-exchange method

The poly(3-hydroxybutyrate) (PHB) organogel monoliths were prepared by nonsolvent-induced phase separation (NIPS). The NIPS-derived organogels were solvent-exchanged with chitosan (CS) solution, resulting in the successful loading of CS into PHB hydrogel. With increasing the CS content, the as-prepared composite hydrogels became syringe injectable with excellent thixotropy due to the increase in the gel network's hydrophilicity. The hydrogels were successfully freeze-dried into PHB/CS composite aerogels, which exhibited remarkably improved compressive modulus/collapse strength of 1.6 MPa/159 kPa compared to 0.5 MPa/31 kPa for pure PHB aerogels. The effect of CS on gel crystallization and structure was also investigated. The amphiphilic PHB/CS hydrogels effectively entrapped both hydrophilic/cationic doxorubicin (DOX) and hydrophobic/anionic indomethacin (IDM). The drug release behavior depended on the charge interactions between drugs and CS. The accelerated DOX release in acidic condition from injected hydrogels owing to the charge repulsion shows potential for a controlled and localized cancer therapy.

Strong and tough cellulose–graphene oxide composite hydrogels by multi-modulus components strategy as photothermal antibacterial platform

Biomacromolecule-derived hydrogels have gained increased attention owing to their favorable hydrophilicity, flexibility, biocompatibility, and biodegradability. However, enhancing the mechanical strength of these hydrogels, while simultaneously improving their toughness remains a challenging task. Herein, a strategy of using multi-modulus components is proposed to fabricate strong and tough cellulose–graphene oxide (GO) composite hydrogels. The GO nanosheet content, molar ratio of the GO crosslinker to anhydroglucose units of cellulose, and ethanol concentration are shown to be critical parameters for achieving cellulose–GO nanosheet composite hydrogels with high strength and high toughness; the highest stress and work of fracture of the as-prepared composite hydrogels reached 13.6 MPa and 1.47 MJ/m3, respectively, in the compressive mode, and 2.8 MPa and 1.40 MJ/m3, respectively, in the tensile mode. The strengthening and toughening mechanism of the hydrogels composed of multi-modulus components is discussed. Moreover, the composite hydrogels exhibited excellent photothermal antibacterial properties against Escherichia coli and Staphylococcus aureus under near-infrared irradiation. We anticipate that the strategy of using multi-modulus components will inspire new design principles toward the development of high-strength and high-toughness biomacromolecule-derived hydrogels for biomedical devices, flexible bioelectronics, and others.

Construction of a Mesoporous Polydopamine@GO/Cellulose Nanofibril Composite Hydrogel with an Encapsulation Structure for Controllable Drug Release and Toxicity Shielding.

The development of intelligent and multifunctional hydrogels having photothermal properties, good mechanical properties, sustained drug release abilities with low burst release, antibacterial properties, and biocompatibility is highly desirable in the biomaterial field. Herein, mesoporous polydopamine (MPDA) nanoparticles wrapped with graphene oxide (GO) were physically cross-linked in cellulose nanofibril (CNF) hydrogel to obtain a novel MPDA@GO/CNF composite hydrogel for controllable drug release. MPDA nanoparticles exhibited a high drug loading ratio (up to 35 wt %) for tetracycline hydrochloride (TH). GO was used to encapsulate MPDA nanoparticles for extending the drug release time and reinforcing the physical strength of the obtained hydrogel. The mechanical strength of the as-fabricated MPDA@GO/CNF composite hydrogel was five times greater compared to that of the pure CNF hydrogel. Drug release experiments demonstrated that burst release behavior was significantly reduced by adding MPDA@GO. The drug release time of the MPDA@GO/CNF composite hydrogel was 3 times and 7.2 times longer than that of the polydopamine/CNF hydrogel and pure CNF hydrogel, respectively. The sustained and controlled drug release behaviors of the composite hydrogel were highly dependent on the proportion of MPDA and GO. Moreover, the rate of drug release could be accelerated by near-infrared (NIR) light irradiation and pH value change. The drug release kinetics of the as-prepared composite hydrogel was well described by the Korsmeyer-Peppas model, and the drug release mechanism of TH from the composite hydrogel was anomalous transport. Importantly, this carefully designed MPDA@GO/CNF composite hydrogel showed good biocompatibility through an in vitro cytotoxicity test. In particular, the toxicity of GO was well shielded by the CNF hydrogel. Therefore, this novel MPDA@GO/CNF composite hydrogel with an encapsulation structure for controllable drug release and toxicity shielding of GO could be used as a very promising controlled drug delivery carrier, which may have potential applications for chemical and physical therapies.

High-strength and tough composite hydrogels reinforced by the synergistic effect of nano-doping and triple-network structures

Developing composite hydrogels with superior compressive mechanical performances attracted wide attention in recent years. In this work, a novel designing strategy was proposed to prepare a GOs/Fe3+-CMC/PVA triple-network (TN) hydrogel by a simple three-step procedure, including chemical polymerization, metal ionic coordination, and repeated freezing/thawing cyclic. The microstructures, functional groups, and elements distribution of the composite hydrogels were characterized by High resolution scanning electron microscope (HRSEM), Fourier transform Infrared (FTIR) and Energy dispersive X-ray (EDX) analysis, respectively. Furthermore, the compressive mechanical properties of the hydrogels with different mass ratios of GOs/PVA (0.4% ~2.0%), CMC/PVA (0.04~0.20), and freezing/thawing cyclic numbers (0, 5, & 9 times) were evaluated, respectively. The synthetic TN composite hydrogels with optimized compositions exhibited excellent mechanical strength (5.366 ± 0.58 MPa) and toughness (617.4 ± 39 kJ/m3). Besides, the as-prepared composite hydrogels owned rapid recovery and fatigue resistance abilities. More importantly, it has analyzed the specific toughening role of each network during the energy dissipation process. The designing strategy may provide a new idea for developing high-strength and tough TN hydrogels and understanding their toughening mechanisms.

Fibers reinforced composite hydrogels with improved lubrication and load-bearing capacity

Hydrogels as one kind of soft materials with a typical three-dimensional (3D) hydrophilic network have been getting great attention in the field of biolubrication. However, traditional hydrogels commonly show poor tribology performance under high-load conditions because of their poor mechanical strength and toughness. Herein, pure chemical-crosslinking hydrogels mixed with different types of the micron-scale fibers can meet the requirements of strength and toughness for biolubrication materials, meanwhile the corresponding tribology performance improves significantly. In a typical case, three kinds of reinforcement matrix including needle-punched fibers, alginate fibers, and cottons are separately combined with Poly(n-vinyl pyrrolidone)-poly(2-hydroxyethyl methacrylate (PVP-PHEMA) hydrogels to prepare fibers reinforced composite hydrogels. The experimental results show that the mechanical properties of fibers reinforced composite hydrogels improve greatly comparable with pure PVP-PHEMA hydrogels. Among three kinds of fibers reinforced composite hydrogel, the as-prepared composite hydrogels reinforced with needle-punched fibers possess the best strength, modulus, and anti-tearing properties. Friction tests indicate that the fibers reinforced composite hydrogels demonstrate stable water-lubrication performance comparable with pure PVP-PHEMA hydrogels. Besides, the hydrogel-spunlace fiber samples show the best load-bearing and anti-wear capacities. The improved tribology performance of the composite hydrogels is highly related to mechanical property and the interaction between the fibers and hydrogel network. Finally, spunlace fibers reinforced hydrogel materials with high load-bearing and low friction properties are expected to be used as novel biomimetic lubrication materials.

Rapid gelation of oxidized hyaluronic acid and succinyl chitosan for integration with insulin-loaded micelles and epidermal growth factor on diabetic wound healing.

In this work, poly(ethylene glycol)-b-poly[3-acrylamidophenylboronic acid-co-styrene] (PEG-b-P(PBA-co-St) has been firstly synthesized for loading of insulin to form insulin-loaded micelles. Insulin-loaded micelles (ILM) and epidermal growth factor (EGF) are further embedded into the composite hydrogels that can be rapidly gelled by mixing of oxidized hyaluronic acid (OHA) and succinyl chitosan (SCS). Then, the morphology, rheology, degradation, swelling and cytotoxicity properties of the as-prepared composite hydrogels are further investigated to evaluate their physical properties and biocompatibility of as the wound dressing. The as-prepared composite hydrogels show the excellent cell compatibility and low toxicity. To evaluate the wound healing ability of as-prepared composite hydrogels, the tests of wound healing in vivo are conducted on streptozotocin-induced rat models. And the as-prepared composite hydrogels with ILM and EGF show an excellent wound healing performance for promotion of fibroblast proliferation and tissue internal structure integrity, as well as the deposition of collagen and myofibrils. These results suggest that the as-prepared composite hydrogels with loading of ILM and EGF could be a promising candidate for wound healing applications.

CuS@Corn Stalk/Chitin Composite Hydrogel for Photodegradation and Antibacterial.

Copper sulfide nanoparticles (CuS NPs) have recently attracted extensive attention in various fields due to their excellent optical and electrical properties. However, CuS NPs are easy to agglomerate in their preparation on account of the high surface activity. In this study, uniform dispersion of CuS NPs were fabricated with corn stalk as a template and stabilizer, further CuS@corn stalk/chitin composite hydrogel was obtained by crosslinking with chitin. The results reveal that the CuS NPs were evenly dispersed into the composite hydrogels with a three-dimensional network structure, which were verified by the UV-vis spectrum, XRD, FT-IR spectra and SEM. In addition, the as-prepared composite hydrogel with the traits of peroxidase-like activity can convert H2O2 into an extremely oxidative and toxic ·OH, which manifested good effects for photodegradation of RhB and antibacterial against Escherichia coli and Staphylococcus aureus. Hence, the composite hydrogels could be used for photocatalytic treatment and sterilization of wastewater, which provides a new idea for the functional application of CuS NPs.

Polyethyleneimine-modified graphene oxide/PNIPAm thermoresponsive hydrogels with rapid swelling/deswelling and improved mechanical properties

Surface-functionalized graphene oxide (GO) was prepared by reacting GO with polyethyleneimine (PEI) at room temperature. Fourier transform infrared spectroscopy indicates the preparation of PEI-decorated GO (PEI-GO) and dual roles of PEI in preparing PEI-GO. Temperature-sensitive PEI-GO/PNIPAm composite hydrogels with porous structure were prepared by an in situ freezing polymerization method. The composite hydrogels were characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and differential scanning calorimetry. The swelling and deswelling properties, temperature sensitivity and mechanical performance of as-prepared composite hydrogels were also investigated systematically. The rapid swelling and deswelling rates as well as superior mechanical property were achieved by introducing robust PEI-GO sheets into the porous polymer matrix. The maximum tensile strength of composite hydrogel was 34 kPa when the content of PEI-GO was 3.6%, three times larger than that of neat PNIPAm hydrogel.

Effective photocatalytic degradation of Congo red dye using alginate/carboxymethyl cellulose/TiO2 nanocomposite hydrogel under direct sunlight irradiation

Abstract Nanocomposite hydrogels of barium ion crosslinked alginate/carboxymethyl cellulose (CMC) with encapulation of TiO 2 -NPs were synthesized sucessfully using dissipative convective method followed by freeze-drying procedure. As-prepared composite hydrogels were charecterized by different techniques such as Fourier Transform Infrared spectroscopy (FT-IR), Powder X-ray diffraction (PXRD), UV- Diffuse reflectance spectroscopy (UV-DRS), BET-Surface area study, Scanning Electron Microscopy with Energy Dispersive X-ray analysis (SEM-EDAX), Transmission Electron Microscopy (TEM) and mechanical strength study. Ba/Alg/CMC/TiO2 composite hydrogels exhibited excellent photocatalytic activity towards CR under direct solar light irradiation with pseudo-first order kinetics. The recycling ability of Ba/Alg/CMC/TiO2 composite hydrogels confirms that photocatalyst is highly photostable.