Alcohol Composite Hydrogel Research Articles

Ultra-strong hydroxypropyl cellulose/polyvinyl alcohol composite hydrogel by combination of triple-network and mechanical training

To develop the hydrogels with high mechanical strength and excellent conductivity is always a challenging topic. In this study, the ultra-strong hydroxypropyl cellulose (HPC)/polyvinyl alcohol (PVA) composite hydrogels were prepared by combination of the triple-network and mechanical training. The proposed composite hydrogels were achieved by physically crosslinking HPC with PVA to form the first crosslinking network, in which the HPC fibers could decrease the crosslinking density of PVA matrix and generate a lot of water-rich porous area. Then, 2-hydroxyethyl acrylate (HEA), acrylamide (AM) and aluminium chloride diffused into the first network to fabricate the chemical crosslinking network and ionically cross-linked domains. The formation of triple-network enhanced the mechanical strength and toughness to 1.87 MPa and 339.09 kJ/m3, respectively. Especially, the crystalline domains of PVA chains could improve the hydrogel's fatigue resistance, and the orderly arrangement of the crystalline domains achieved through mechanical training process could further enhance the mechanical strength. The mechanical strength of pre-stretched composite hydrogel was increased up to 2.8 MPa. The composite hydrogels exhibit great applications in sensors, human–machine interactions, and wearable devices.

Biomimetic MXene‐Polyvinyl Alcohol Composite Hydrogel with Vertically Aligned Channels for Highly Efficient Solar Steam Generation

AbstractSolar steam generation, which utilizes sustainable solar energy to produce fresh water, is regarded as a facile and effective way to solve water scarcity issues. However, challenges remain in terms of inefficient water transfer and vapor release, low solar absorption and conversion efficiency, and hydrophobic photothermal materials. Herein, enlightened by water transport through internal microchannels in trees, a tree‐inspired hydrogel (TIH) with vertically aligned channels incorporating MXene as the light absorber is fabricated. Due to the vertically aligned channels, the rapid transfer of water and unobstructed release of steam can be achieved. Furthermore, water state in molecular meshes can be changed by polymer−water interaction, and partial water can be activated to promote water evaporation. Excellent internal photothermal conversion efficiency and hydrophilicity of MXene are also conducive to evaporation. As a result, TIH has achieved an evaporation rate of 2.71 kg m−2 h−1 and energy efficiency of 90.7% under one sun irradiation, which is higher than membrane material and structure‐disordered hydrogel. This design principle, expandable manufacturing route, and excellent performance provide a potential way and design concept for water purification and desalination.

Physically-crosslinked polyvinyl alcohol composite hydrogels containing clays, carbonaceous materials and magnetic nanoparticles as fillers

Polyvinyl alcohol (PVA)/ Bentonite, acid-modified Bentonite, magnetic nanoparticles and mesoporous carbonaceous composite hydrogels were synthesized via an eco-friendly freeze-thawing technique, which is a simple and non-toxic crosslinking methodology. After thorough characterisation using X-Ray Diffraction (XRD), Scanning Electron microscopy (SEM), Dynamic Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and swelling assessment.Furthermore, the prepared materials were tested in order to explore their cadmium adsorption potential, a heavy metal usually found as a pollutant in water bodies. The data obtained showed that PVA has no affinity for cadmium ions but the incorporation of the different fillers makes the materials develop important adsorbent characteristics. Under the selected working conditions, and for a contact time of 1440 min, the maximum amount of cadmium ions adsorbed was 50.9 mg/g, 33.9 mg/g, 42.6 mg/g and 30.5 mg/g for composites containing bentonite; acid-modified bentonite; magnetic nanoparticles and carbonaceous materials, respectively. For all cases the higher the filler amounts the higher the adsorption efficiency.

Synthesis and characterization of biomass lignin-based PVA super-absorbent hydrogel

The traditional polyvinyl alcohol composite hydrogel exhibited poor swelling and mechanical properties, which limited its application. To solve these issues, we use biomass lignin as raw material, PVA as matrix template and epichlorohydrin as cross-linker to prepare the Lignin-PVA super-absorbent hydrogels with the swelling ratio of up to 456 g/g under mild condition. When the lignin concentration was increased from vacancy to 5%, the swelling ratio of the Lignin-PVA hydrogels was increased from 92 g/g to 456 g/g. The lignin-based hydrogel synthesized by the higher molecular weight PVA showed better swelling performance. Softwood lignin, hardwood lignin and corncob lignin could also be used to fabricate the Lignin-PVA super-absorbent hydrogels with the swelling ratio of higher than 500 g/g. However, the optimum amount varied from different lignin types, which was related to the molecular weight and phenolic hydroxyl content of lignin. The structural mechanism of the Lignin-PVA hydrogel was proposed to clearly certify the enhancing role of lignin. The adsorption capacity of the Lignin-PVA hydrogel with respect to rhodamine 6G, crystal violet and methylene blue dyes was up to 196, 169 and 179 mg/g, respectively. The Lignin-PVA hydrogel presents great potential applications in the fields of soil water retention and seed cultivation in agriculture, and dye pollutant removal.

Preparation and performance investigation of polydimethylsiloxane microsphere/polyvinyl alcohol composite hydrogel

In this work, we designed an emulsion method to prepare polydimethylsiloxane microspheres in polyvinyl alcohol aqueous solution. Here, polyvinyl alcohol was utilized as both emulgator/dispersant and raw material, and homogeneous polydimethylsiloxane microsphere/polyvinyl alcohol composite hydrogels were fabricated. This strategy avoided the aggregation/adhesion of polydimethylsiloxane microspheres, and provided new thought for compositing the immiscible phases. The as-obtained composite hydrogels showed relatively high equilibrium water content and swelling ratio, as well as enhanced water retention and compressive modulus.

Hydroxyapatite/Polyvinyl Alcohol Composite Hydrogels for Bone and Cartilage Tissue Engineering

Composite hydrogels on the basis of hydroxyapatite (HAp) and polyvinyl alcohol (PVA) has been proposed as a promising materials for bone and cartilage tissue engineering. HAp/PVA composite hydrogels with phase ratio 50:50wt% and 70:30wt% were obtained via in situ wet chemical precipitation technique in combination with the freeze-thawing approach. The XRD studies of sintered products revealed that HAp/PVA composite hydrogels synthesized from PVA with degree of hydrolysis (DH) 98% and molecular weights (MW) 25 kDa and 78 kDa are more suitable for biomedical purposes due to the formation of stoichiometric HAp. Swelling studies indicated that HAp/PVA 50:50 (78 kDa, 88% and 98%) hydrogels after 24h of immersion swell ~4.25-6.5 times less than identical samples with phase composition of 70:30wt%, which is accounted to different number of intermolecular hydrogen bonds formed. After 16 subsequent freeze-thawing cycles (FTC), HAp/PVA 50:50 (78 kDa, 88% and 98%) hydrogels contain ~1.2 times higher content of crosslinked PVA than HAp/PVA 70:30 (78 kDa, 88% and 98%) hydrogel samples.

Preparation, properties and formation mechanism of cellulose/polyvinyl alcohol bio-composite hydrogel membranes

Aggregate sheets formed by hydrophobic interactions of cellulose act as physical junctions in the cellulose/polyvinyl alcohol composite hydrogel.

Preparation and Properties of Heparin Sodium/Polyvinyl Alcohol Composite Hydrogel

Preparation and Properties of Heparin Sodium/Polyvinyl Alcohol Composite Hydrogel

Preparation and Properties of Porous β-Tricalcium Phosphate/Chitosan/Polyvinyl Alcohol Composite Hydrogel

Porous β-tricalcium phosphate/chitosan/polyvinyl alcohol(β-TCP/CS/PVA) composite hydrogel was prepared successfully by the freezing-thawing method using NaCl as porogen.The effects of different mass ratio of CS to β-TCP on the crystallinity of PVA and the performance of target β-TCP/CS/PVA composite hydrogel has been studied.The products were characterized by means of XRD,SEM,TG-DTA and their water uptake,swelling ratio,and tensile strength were also determined and compared.The water uptake of the hydrogel composite was about 70%~76%(mass fraction).When the mass ratio of CS to β-TCP was 2∶ 8,it exhibited good mechanical properties: tensile strength of 0.56 MPa and elongation at breakage of 370% which can withstand normal human eye pressure.Therefore,the porous β-TCP/CS/PVA hydrogel composite is promising to be used as the skirt for artificial cornea.

Preparation of a Composite Biosorbent Using Scenedesmus quadricauda Biomass and Alginate/Polyvinyl Alcohol for Removal of Cu(II) and Cd(II) Ions: Isotherms, Kinetics, and Thermodynamic Studies

In this study, microalgae Scenedesmus quadricauda was entrapped in calcium alginate/polyvinyl alcohol composite hydrogel beads by phase-inversion techniques. The composite biosorbents were used for removal of Cu(II) and Cd(II) ions from single component and binary systems using cell-free composite beads as a control system. The effects of the experimental conditions (such as pH, initial metal ions concentrations, temperatures, contact time, and biosorbent concentrations) on Cu(II) and Cd(II) removal efficiencies were studied. The maximum metal ions on the bare and algal biomass immobilized in alginate beads were observed between pH 5.0 and 6.0. The biosorption of metal ions by the bare and composite beads increased as the initial concentration of the metal ions increased in the medium. The biosorption of Cu(II) and Cd(II) on the composite beads appears to be slightly temperature dependent. The maximum biosorptions of metal ions onto microalgae entrapped in composite beads were 0.970 ± 0.028 and 0.682 ± 0.017 mmol/g for Cu(II) and Cd(II) ions, respectively. The equilibrium experimental data for two metallic species fitted well by the Langmuir model. The values of ΔG° at all temperatures are negative, indicating the spontaneous nature of the biosorption process. When the metal ions competed (in the case of the biosorption from their mixture), the amounts of biosorption onto microalgae cells entrapped in beads were 0.857 ± 0.033 mmol/g for Cu(II) and 0.593 ± 0.024 mmol/g for Cd(II). Under noncompetitive and competitive conditions, the affinity order of ions for biosorbents was Cu(II) > Cd(II).

High strength graphene oxide/polyvinyl alcohol composite hydrogels

Polyvinyl alcohol (PVA) hydrogels have been proposed for use as promising biomaterials in biomedical and tissue engineering but their poor mechanical and water-retention properties have hindered their development. Graphene oxide (GO), an excellent nanofiller, was added to PVA to make GO/PVA composite hydrogels by a freeze/thaw method. The mechanical properties of the GO/PVA hydrogels were significantly improved. Compared to pure PVA hydrogels, a 132% increase in tensile strength and a 36% improvement of compressive strength were achieved with the addition of 0.8 wt% of GO, which suggests an excellent load transfer between the GO and the PVA matrix. The incorporation of certain amount of GO into composite hydrogels does not affect the toxicity of PVA to osteoblast cells.

In vivo experimental study of lumbar nucleus replacement with pectin/polyvinyl alcohol composite hydrogel

To evaluate the anti degenerative effect of pectin/polyvinyl alcohol composite (CoPP) hydrogel as artificial nucleus material in an animal model. Thirty-six New Zealand white rabbits were used to build animal models, the L₄₋₅ intervertebral discs were pierced with a Gauge#16 needle and polyvinyl alcohol (PVA) or CoPP implants were inserted into the holes. For comparative purposes, L₃₋₄ discs underwent sham treatment or control treatment in which the disc was pierced but no implant was inserted. All the discs were divided into four groups as follows: sham disc group, pierced disc group, PVA disc group and CoPP disc group. The discs were analyzed radiologically and histologically for degenerative changes at 1, 3 or 6 months after surgery. None of the animals died from operative complications, such as paraplegia or infection before being killed. Macroscopically, none of the implants showed any signs of displacement at the time of harvest. The radiological analysis revealed that significantly less disc height loss was found with the PVA and CoPP replacement treatment than with the pierced treatment (P < 0.05). Changes in disc height after the replacement treatment were not significantly different from that after the sham treatment (P > 0.05). Histological degeneration of the replaced discs was delayed in comparison with that of the pierced discs (P < 0.05), but progressed with time, and PVA replacement showed faster disc degeneration than CoPP replacement. Degeneration of the anulus fibrosus after the CoPP prosthetic nucleus replacement treatment is delayed by preserving disc height and occupying the space of the nucleus pulposus, and it has great potential clinical application value.

Preparation and characterization of bioglass/polyvinyl alcohol composite hydrogel

In order to form firm active fixation with the adjacent bone, a new kind of bioactive composite hydrogel was prepared with polyvinyl alcohol (PVA) and bioglass (BG) through ultrasonic dispersion, heat-high-pressure and freeze/thawed technique. A digital speckle correlation method (DSCM) was utilized to characterize the mechanical properties of the series of BG/PVA composites. Results showed that at different load pressures, the composite hydrogel displayed different displacement and deformation in the V field. Results also showed that an increase of PVA percentage (15–30 wt%) or of bioglass percentage (2–10 wt%) in composite hydrogel could lead to an increase in the elastic compression modulus. Scanning electron microscope results indicated that bioglass was uniformly dispersed in the BG/PVA composite hydrogel. The BG/PVA composite hydrogel shows a promising prospect as a new bionic cartilage implantation material.