In previous work, we have developed a dual physically cross-linked hydrogel composed of poly (acrylamide-co-acrylic acid) (PAM-co-PAA) and polyvinyl alcohol (PVA), named as PVA/CP DN gel, by facile copolymerization and freezing/thawing. The PVA/CP DN gel is featuring both excellent mechanical properties and self-healing ability. Additionally, we have preliminarily found that the comonomer ratio for PVA/CP DN gel have great influence on the self-healing efficiency. In this research article, we will further discuss the mechanical and self-healing properties of the PVA/CP DN gel by varying the comonomer ratio of PAM-co-PAA. The results proved that the structure of DN will be loosen when the number of PAA segments exceed that of PAM. More PAA segments in copolymer make the PVA/CP DN gel have better elongation at break but weak in tensile strength and young’s modulus because of less PVA crystalline domains formed in the gel. The energy dissipation value for the double-network hydrogel decrease with the addition of PAA segments, whereas self-healing efficiency of PVA/CP DN gel increased. Anyway, this work provides more information to further understand the effects of composition on the properties of dual physically cross-linked PVA/CP DN hydrogel. 相似文献
A series of hybrid hydrogels based on poly(vinyl alcohol) (PVA)/agar/poly(ethylene glycol) (PEG) prepared by a solution casting method using e‐beam irradiation are investigated to determine the effect of agar and PEG content (1, 2, and 4 wt%) on their physicomechanical and rheological properties. The gel content of the hydrogels decreases with increasing agar and PEG contents. The equilibrium swelling of PVA hydrogel decreases on blending with agar while adding PEG to PVA/agar increases the swelling by about 400%. No obvious change in the dehydration behavior of the hybrid hydrogels is observed on changing agar and PEG contents. The solid‐like rheological behavior of the hydrogels is not significantly affected by agar content, while it approaches a liquid‐like behavior at high PEG loading. The tensile strength of the hybrid hydrogels is improved by increasing agar content, while its elongation‐at‐break is decreased. On the other hand, the opposite results are found regarding the influence of PEG and its content on the mechanical properties of the hybrid hydrogels.
Polyvinyl alcohol (PVA) hydrogel is a promising material possessing good chemical stability, high water absorption, excellent biocompatibility and biological aging resistant. However, the poor mechanical performance of PVA hydrogel limits its applications. Here we report the utilization of one-dimensional (1D) BN nanofibers (BNNFs) as nanofillers into PVA matrix to prepare a novel kind of BNNFs/PVA composite hydrogel via a cyclic freezing and thawing method. For comparison, the composite hydrogels using spherical BN nanoparticles i.e. BN nanospheres (BNNSs) as fillers were also prepared. The mechanical properties, thermal stabilities and swelling behaviors of the composite hydrogels were investigated in detail. Our study indicates that the mechanical properties of the hydrogels can be improved by adding of BNNFs. After loading of BNNFs into PVA with content of 0.5?wt%, the compressive strength of the composite hydrogel increases by 252% compared with that of pure PVA hydrogel. The tensile performance of BNNFs/PVA composite hydrogels has also been improved. Impressive 87.8% increases in tensile strengths can be obtained with 1?wt% BNNFs added. In addition, with the increase of BNNFs content, the thermal stability and the swelling ratio of hydrogels are increased gradually. The swelling ratio of hydrogel increases by 56.3% with only 1?wt% BNNFs added. In comparison, the improvement effects of the BNNS fillers on the mechanical strengths and swelling ratios are much weaker. The enhanced effects of BNNFs can be ascribed to the strong hydrogen bond interaction between BNNFs and PVA. The high aspect ratios of the nanofibers should also be took into account. 相似文献
Hydrogels have the potential to simulate and permeate body tissues. They can be used in many biomedical applications, such as drug delivery, wound dressings, contact lenses, synthetic implants, biosensors, and tissue engineering. Despite recent significant advances in hydrogel fabrication, with the introduction of double network hydrogels, with ionic or hydrogen bonds, there is still the challenge of achieving optimal mechanical properties with appropriate self-healing ability. To solve the above problem, in this study, a new type of starch/chitosan/PVA/borax hydrogel was synthesized by adopting the one-pot method. The effect of concentration and ratio of raw materials on the final properties of hydrogels, such as the degree of hydrophilicity, morphology, degradation, mechanical strength, and drug release rate, was investigated. The properties of hydrogels were examined by scanning electron microscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, X-ray diffractometry, and contact angle, which confirmed the composite synthesis and uniform distribution of HNT and curcumin. In addition, the composite hydrogel showed excellent mechanical properties. Drug release studies confirmed that the drug is slowly released from the nanocomposite hydrogels. The results showed that starch-based nanocomposite hydrogels could provide appropriate repairing potential for defects exposed to changeable parameters. 相似文献
Three crosslinkers, poly(ethylene glycol) diacrylate (PEGDA), glycerol ethoxylate triacrylate (GETA) and citric acid-(PEG acrylate)3 (CA-PEGTA) derived from poly(ethylene glycol) (PEG) were synthesized at first. The three series of poly (N-isopropylacrylamide) (PNIPAAm) hydrogels were prepared by photopolymerization with the crosslinkers and compared with a hydrogel based on commercial crosslinker, N,N′-methylene bis-acrylamide (NMBA). The influence of the crosslinker structures and contents on the swelling behaviour, mechanical properties, and drug release of the hydrogels was investigated. The results showed that the hydrogels based on PEGDA and NMBA exhibited the highest and the lowest swelling ratio, respectively. The content of crosslinker of all hydrogel series showed good thermosensitivity and thermo-reversibility. The critical gel transition temperature (CGTT) appeared at 32 °C for the hydrogel based on NMBA, but appeared at about 34 °C for other hydrogels due to higher hydrophilicity of the crosslinker. In the mechanical properties, three-arms crosslinker GETA and CA-PEGTA led to higher mechanical strength than a linear crosslinker PEGDA. A hydrogel based on GETA (NG6) showed the highest shear modulus of 656.9 kPa and Young’s modulus of 1655.0 kPa. The hydrogels containing higher content of crosslinker revealed lower swelling ratio and higher mechanical strength. In the drug release, the hydrogels with higher swelling ratios showed higher drug absorbed. The highest release percentage of caffeine and vitamin B12 for hydrogel based on PEGDA (NP6) could reach 68.3% and 75.4%, respectively. In addition, the bound water and toxicity of the hydrogels were also investigated.
Self-healing hydrogels often possess poor mechanical properties which largely limits their applications in many fields. In this work, boron nitride nanosheets are introduced into a network of the poly(vinyl alcohol)/borax (PVA/borax) hydrogels to enhance the mechanical properties of the hydrogel without compromising the self-healing abilities. The obtained hydrogels exhibit excellent mechanical properties with a tensile strength of 0.410 ± 0.007 MPa, an elongation at break of 1712%, a Young's Modulus of 0.860 ± 0.023 MPa, and a toughness of 3.860 ± 0.075 MJ m−3. In addition, the self-healing efficiency of the hydrogels is higher than 90% within 10 min at room temperature. Benefiting from the excellent self-healing properties, the shapeability of the hydrogel fragments is observed using different molds. In addition, the hydrogels display rapid pH-driven shape memory effects and can recover to their original shape within 260 s. Overall, this work provides a new approach to hydrogels with integrated excellent mechanical properties, self-healing abilities, and rapid pH-driven shape memory effects. 相似文献
Vinyl polymers are widely used in biological, textile and industrial applications and are currently attracting research attention for specialized bio-based applications. Polyvinyl alcohol (PVA) hydrogels show great advantages as a material with high biocompatibility, permeability, hydrophilicity, and low-friction coefficient, allowing applications as smart materials, wound dressings, and flexible sensors. However, the poor mechanical properties of PVA hydrogels and biocompatibility less than natural polymers make them unsuitable in practical applications. Additives are often added to PVA hydrogels to enhance mechanical properties, endow more compatibility, functionality and expand their application range. Among them, bio-additives such as nanocellulose, natural polysaccharides and proteins are biodegradable, biocompatible, and inexpensive, broadening their applications in the biomedical and tissue engineering fields. This work reviews the synthesis of PVA hydrogels, methods to enhance their mechanical properties, types of bio-additives incorporated for biocompatibility, their mechanism of interaction with PVA and future prospects of PVA composite bio-hydrogels for application in various fields. Representative cases are carefully selected and discussed with regard to their composition and pros and cons are discussed. Finally, future requirements, as well as the opportunities and challenges of these bio-additives for improving the multifunctionality of PVA hydrogels are also presented. 相似文献
Titanium alloys with excellent mechanical properties and biocompatibility are widely used in surgical implants. However, due to its poor tribological properties, it is difficult to be used in joint bearing interfaces. Herein, mimicking the soft/hard hierarchical structure of articular cartilage/subchondral bone and the unique lubrication mechanisms of articular cartilage, a biomimetic bilayer coating consisting of a TiO2 layer and a hydrogel layer was fabricated on laser-textured Ti6Al4V alloy by laser surface texturing, thermal oxidation and ultraviolet radiation techniques. Meanwhile, a zwitterionic polymer (SBMA) was introduced into the hydrogel layer to provide hydration lubrication. The experimental results demonstrated that the introduction of SBMA greatly improved the hydrophilicity and compressive modulus of the hydrogel layer. Compared with Ti6Al4V, the Ti6Al4V-hydrogel bearing interface exhibited a lower friction coefficient (0.06) and better wear resistance when lubricated in deionized water. More importantly, this Ti6Al4V-hydrogel bearing interface could maintain stable and low friction coefficients when lubricated in different physiological solutions for a long-term friction (4 h), and the lowest friction coefficient (0.039) was measured in phosphate buffer (PBS) solution. The outstanding biotribological performance was mainly attributed to the biphasic and hydration lubrication mechanisms of the hydrogel layer. This study provides new insights into the development of Ti6Al4V bearing interfaces for artificial joints. 相似文献
Various hydrogel systems have been developed as biomaterial inks for bioprinting, including natural and synthetic polymers. However, the available biomaterial inks, which allow printability, cell viability, and user-defined customization, remains limited. Incorporation of biological extracellular matrix materials into tunable synthetic polymers can merge the benefits of both systems towards versatile materials for biofabrication. The aim of this study was to develop novel, cell compatible dual-component biomaterial inks and bioinks based on poly(vinyl alcohol) (PVA) and solubilized decellularized cartilage matrix (SDCM) hydrogels that can be utilized for cartilage bioprinting. In a first approach, PVA was modified with amine groups (PVA-A), and mixed with SDCM. The printability of the PVA-A/SDCM formulations cross-linked by genipin was evaluated. On the second approach, the PVA was functionalized with cis-5-norbornene-endo-2,3-dicarboxylic anhydride (PVA-Nb) to allow an ultrafast light-curing thiol-ene cross-linking. Comprehensive experiments were conducted to evaluate the influence of the SDCM ratio in mechanical properties, water uptake, swelling, cell viability, and printability of the PVA-based formulations. The studies performed with the PVA-A/SDCM formulations cross-linked by genipin showed printability, but poor shape retention due to slow cross-linking kinetics. On the other hand, the PVA-Nb/SDCM showed good printability. The results showed that incorporation of SDCM into PVA-Nb reduces the compression modulus, enhance cell viability, and bioprintability and modulate the swelling ratio of the resulted hydrogels. Results indicated that PVA-Nb hydrogels containing SDCM could be considered as versatile bioinks for cartilage bioprinting. 相似文献