Effect of polyethylene glycol molecular weight on cell growth behavior of polyvinyl alcohol/carboxymethyl cellulose/polyethylene glycol hydrogel

Polyvinyl alcohol (PVA)/carboxymethyl cellulose (CMC)/polyethylene glycol (PEG) hydrogel scaffolds are synthesized using cyclic freezing/thawing and subsequent γ-ray irradiation to evaluate the effect of the molecular weights of PEG (200, 400, 1,000, and 2,000) on strength and cell growth behavior of the hydrogels. As the PEG weight increases from 200 to 2,000, the compressive strength and the pore size decreases gradually from 58.0 ± 8.2 kPa to 17.7 ± 6.1 kPa and from 22.7 ± 3.9 μm to 8.5 ± 1.6 μm, respectively. However, the highest swelling rate is obtained for PVA/CMC/PEG400 hydrogels. The irradiated PVA/CMC/PEG400 hydrogels exhibit tailored properties of the swelling rate of 1,148 ± 34.0%, the compressive strength of 42.5 ± 6.6 kPa, the pore size of 14.6 ± 1.9 μm, and cell viability of 184%. In addition, the fastest L-929 cell proliferation and growth with time, verified by the cell proliferation (0–48 hr) and the scratch assay (0–15 hr), was observed for the PVA/CMC/PEG400 hydrogels, indicating that they are highly suitable for potential wound dressings that require fast healing regeneration.     

Controlled release of aspirin from pH‐sensitive chitosan/poly(vinyl alcohol) hydrogel

The aim of this study was to develop a cheap, pH‐sensitive enteric coating of aspirin with biocompatible polymers. A novel approach was used to develop enteric coating from chitosan (CS) and poly(vinyl alcohol) (PVA). Solutions of CS and PVA (5 : 1 mol ratio) were mixed and selectively crosslinked with tetraethoxysilane. IR analysis confirmed the presence of the incorporated components and the existence of siloxane linkages between CS and PVA. The crosslinking percentage and thermal stability increased with increasing amount of crosslinker. The response of the developed coating in different media, such as water, pH (nonbuffer and buffer), and ionic media showed hydrogel properties. All hydrogels showed low swelling in acidic and basic pH media, whereas maximum swelling was exhibited at neutral pH. This pH sensitivity of the hydrogel has been exploited as enteric coating for commercial aspirin tablets. The dissolution test of enteric‐coated aspirin tablet in simulated gastric fluid (pH 1.2) showed 7.11% aspirin release over a period of 2 h, whereas a sustained release of remaining aspirin (83.25%) was observed in simulated intestinal fluid (pH 6.8). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and characterization of polyvinyl borate/polyvinyl alcohol (PVB/PVA) blend nanofibers

In this study, it was aimed to prepare polyvinyl borate/polyvinyl alcohol blend nanofibers by electrospinning process. Polyvinyl borate was synthesized by the condensation reaction of polyvinyl alcohol and boric acid. Polyvinyl borate itself was not suitable for electrospinning process. To improve fiber formation capability, polyvinyl borate was blended with polyvinyl alcohol before electrospinning process. A series of nanofibers with various polyvinyl borate concentrations in polyvinyl alcohol were prepared. Homogeneous and highly porous mat containing 100–250 nm diameter nanofibers were obtained by electrospinning process. According to the FTIR results, boron atoms were found to be integrated into the polymer network. There is not any significant effect of polyvinyl borate content on fiber morphologies according to SEM images. The blend composition with the highest polyvinyl borate content was found to be suitable for thermally stable nanofiber formation according to the TGA results. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

High strength and bioactivity polyvinyl alcohol/collagen composite hydrogel with tannic acid as cross-linker

Hydrogels have great potential applications in biomedical materials, but their applications in complex physiological environments are severely limited by their weak strength and biotoxicity. Generally, synthetic polymer hydrogels and natural polymer hydrogels have complementary advantages in terms of mechanical strength and biological activity. Herein, tannic acid (TA), a natural material, was introduced into the polyvinyl alcohol/collagen (PVA-COL) double network to prepare a hydrogel (PVA-COL-TA) with good bioactivity and mechanical properties. The tensile strength of the composite hydrogel can reach up to 20 times that of the pure PVA hydrogel. And the hydrogel after swelling under physiological conditions also exhibits stable mechanical properties. The introduction of TA can reduce the degradation rate of COL, enabling it to continue to exert biological activity. in vitro cytocompatibility experiments showed that PVA-COL-TA hydrogel has good sustained biological activity and the potential for biomedical materials.     

Characterization of polyvinyl alcohol/gelatin blend hydrogel films for biomedical applications

In the present investigation, attempt was made to prepare blend hydrogel by esterification of polyvinyl alcohol with gelatin. The blend hydrogel was further converted into films by the conventional solution‐casting method. These films were characterized by FTIR, DSC, and X‐ray diffraction studies. The refractive index and viscosity of different composition of the blends were measured in the solution phase of the material. The mechanical properties of the blend films were measured by tensile test. Swelling behavior of the blend hydrogel was also studied. The FTIR spectrum of the blend film indicated complete esterification of the free carboxylic group of gelatin. The DSC results indicate that the addition of gelatin with PVA changes the thermal behavior like melting temperature of PVA, which may be due to the miscibility of PVA with gelatin. The interaction of gelatin with PVA molecule changes the crystallite parameters and the degree of crystallinity. The crystallinity of the blend film was mainly due to gelatin. The comparison of viscosity indicated an increase in the segment density within the molecular coil. The results revealed the changes observed in the properties of the gel, and it enhances the gel formation at viscoelastic phase of the material. The blend film had sufficient strength and water‐holding capacity. The results obtained indicated that the blend film could be used for various biomedical applications such as wound dressing and drug‐delivery systems. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Facile fabrication of tough and biocompatible hydrogels from polyvinyl alcohol and agarose

A polyvinyl alcohol (PVA)-agarose (agar) composite hydrogel (M-PVA-agar-60) was developed by simple three cycles of freeze-thawing, followed by successively soaking in ammonium sulfate aqueous solution to induce phase separation and dialyzing against deionized water to remove residual sulfate salts. Due to the synergy of crystalline regions, hydrogen bonding and phase separation domains, the obtained M-PVA-agar-60 hydrogel exhibits excellent mechanical properties (tensile strength = 1.1 MPa, tensile strain = 324% and compressive stress = 12.5 MPa), combined with a high water content of 87.0%. Moreover, the hydrogel hardly expands after immersing in the phosphate-buffered saline aqueous solution at 37°C for a week, and the tensile stress and toughness remain almost the same as their initial values, superior to most reported non-swellable hydrogels. Because of the biocompatible starting materials, absence of toxic chemicals, and dialysis in advance to remove ammonium sulfate, the hydrogel also shows excellent cell compatibility, making it an ideal candidate for tissue engineering materials.     

Preparation and characterization of LDPE/PVA blend films filled with glycerin‐plasticized polyvinyl alcohol

A series of LDPE/PVA blend films were prepared via a twin‐screw extruder, and their morphology, thermal property, oxygen and water vapor permeation, surface properties, and mechanical properties were investigated as a function of the PVA content. During the extrusion process of the blend films, glycerin improved the compatibility and processing conditions between LDPE and PVA. The melting temperature (T_m), melting enthalpy (ΔH_m), crystallinity (%), and thermal stability of the thermal decomposition temperature (T_5%) of the LDPE/PVA blend films decreased with increasing PVA content. The oxygen permeabilities of the blend films decreased from 24.0 to 11.4 cm³·cm (m²·day·atm)^?1 at 23°C. The WVTR increased from 7.8 to 15.0 g(m² day)^?1 and the water uptake increased from 0.13 to 9.31%, respectively. The mechanical properties of blend films were slightly enhanced up to 2% PVA and then decreased. The physical properties of the blend films strongly varied with the chemical structure and morphology depending on the PVA and glycerin. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41985.     

pH‐sensitive keratin‐based polymer hydrogel and its controllable drug‐release behavior

Using feather keratin as biocompatible and inexpensive natural biopolymer and methacrylic acid as a functional monomer, we prepared a pH‐sensitive feather‐keratin‐based polymer hydrogel (FKPGel) with grafted copolymerization. The obtained FKPGel was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The swelling behavior and pH sensitivity of the FKPGel were investigated. When the small molecule (rhodamine B) and macromolecule (bovine serum albumin) were used as model drug molecules, the FKPGel exhibited controllable release behavior in vitro, and the hydrogels had pH sensitivity. For a small molecular drug, the cumulative release rate was 97% in 24 h at pH 8.4. For macromolecular drug, the cumulative release rate reached 89% at pH 7.4. Its release behavior could be controlled by the pH value. In summary, a simple method was found to reuse disused feathers. It is a kind of pH‐sensitive hydrogels to be applied in drug‐delivery systems. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41572.     

A comparative assessment of poly(vinylidene fluoride)/conducting polymer electrospun nanofiber membranes for biomedical applications

Piezoelectric polymers, especially poly(vinylidene fluoride) (PVDF) are increasingly receiving interest as smart biomaterials for tissue engineering, energy harvesting, microfluidic, actuator, and biosensor applications. Despite possessing the greatest piezoelectric coefficients among all piezoelectric polymers, it is often desirable to increase the electrical outputs from PVDF for several of these applications. Blending with intrinsically conducting polymers (CP) in the form of nanofiber membranes is one of the facile methods to achieve the same. However, these polymers and their composites have so far been primarily investigated only for their physical property enhancements and in applications like energy storage while their biomedical applications and comparative assessment of their biocompatibility properties have not been yet explored. In this report, electrospinning of PVDF blends with polypyrrole (PPy), polyaniline (PANI), and a modified PANI with l -glutamic acid (PANI-LGA/P-LGA) is performed to obtain different electrically active material membranes. The PVDF:CP composite nanofibers are compared with respect to their nanostructures, β-phase content, and electrical conductivity. Further, biocompatibility of all the membranes was compared. It was found that incorporation of PPy, PANI, and P-LGA increased the electrical conductivity of PVDF while the β-phase content was also substantially enhanced. The highest biocompatibility with a pre-osteoblast cell line (MC3T3) was exhibited in the order p-LGA/PVDF > PANI/PVDF > PPy/PVDF, all being significantly higher than PVDF (p < .001). Although P-LGA/PVDF showed higher electrical conductivity, biocompatibility with MC3T3, it was found to be highly cytotoxic to a HeLa (cancer) cell line. It is concluded that such structure property relations would help in selection of materials for specific biomaterial applications.     

Preparation and characterization of novel pH‐sensitive binary grafted polymeric blends of gelatin and poly(vinyl alcohol): Water sorption and blood compatibility study

In this study, we attempted the synthesis and characterization of novel biocompatible hydrogels of binary polymeric blends of crosslinked poly(acrylic acid) grafted onto poly(vinyl alcohol) and gelatin by a redox polymerization technique. The end polymer was characterized by IR spectral analysis, differential scanning calorimetry measurements, and scanning electron microscopy. The prepared smart, environment‐responsive hydrogels, containing polyelectrolyte domains, were assessed for their water sorption potential under various experimental conditions and were further used to evaluate important network parameters such as the crosslink density, number of elastically effective chains, and molecular mass between crosslinks. The diffusion mechanism of the solvent–polymer interaction was also analyzed to predict the behavior of continuously relaxing chains containing several carboxylate ions. The blood compatibility of premeditated hydrogels was also judged by in vitro methods such as protein adsorption, blood clot formation, and hemolysis percentage assay measurement. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 599–617, 2006     

Study on thermoplastic polyurethane/polypropylene (TPU/PP) blend as a blood bag material

Blends with different ratios of thermoplastic polyurethane/polypropylene (TPU/PP) were prepared by melt mixing using an internal Haake mixer. Properties of the blends were investigated using SEM micrographs of cryofractures and measurement of the mechanical strength, water absorption, cell culture, and platelet adhesion in vitro tests, which were compared with those of PVC blood bags. The effect of the addition of the ethylene–vinyl acetate (EVA) copolymer on the TPU/PP blend properties was investigated. The results indicated that a TPU/PP/EVA = 80/20/5 blend can be used as a new blood bag material. It was observed that the blend is homogeneous with higher mechanical strength than that of the commercial PVC blood bag. This blend also showed a compatible cell response in contact with L929 fibroblast cells and fewer tendencies to interaction with platelets compared to the PVC blood bag. Although the blends were immissible and no chemical reaction at the interface could be found, the blood compatibility of the blends were improved. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2496–2501, 2003     

Bio‐nanocomposite films based on cellulose nanocrystals filled polyvinyl alcohol/chitosan polymer blend

Bio‐nanocomposite films based on polyvinyl alcohol/chitosan (PVA/CS) polymeric blend and cellulose nanocrystals (CNC) were prepared by casting a homogenous and stable aqueous mixture of the three components. CNC used as nanoreinforcing agents were extracted at the nanometric scale from sugarcane bagasse via sulfuric acid hydrolysis; then they were characterized and successfully dispersed into a PVA/CS (50/50, w/w) blend to produce PVA/CS–CNC bio‐nanocomposite films at different CNC contents (0.5, 2.5, 5 wt %). Viscosity measurement of the film‐forming solutions and structural and morphological characterizations of the solid films showed that the CNC are well dispersed into PVA/CS blend forming strong interfacial interactions that provide an enhanced load transfer between polymer chains and CNC, thus improving their properties. The obtained bio‐nanocomposite films are mechanically strong and exhibit improved thermal properties. The addition of 5 wt % CNC within a PVA/CS blend increased the Young's modulus by 105%, the tensile strength by 77%, and the toughness by 68%. Herein, the utilization of Moroccan sugarcane bagasse as raw material to produce high quality CNC has been explored. Additionally, the ability of the as‐isolated CNC to reinforce polymer blends was studied, resulting in the production of the aforementioned bio‐nanocomposite films with improved properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42004.     

Controllable properties and microstructure of hydrogels based on crosslinked poly(ethylene glycol) diacrylates with different molecular weights

This work describes a comprehensive study of hydrogels based on polyethylene glycol diacrylates (PEGDAs) with the molecular weight (MW) range of 400–2000. The blends of low‐ and high‐molecular weight PEGDA macromers with different ratios were photopolymerized under visible light irradiation, using a blue light sensitive photoinitiator Irgacure819, at the total polymer concentration of 60 wt %. Swelling ratios, wetting property, elastic moduli, transparency, and the microstructure of the resulting hydrogels were investigated. Among them, equilibrium water contents, hydrophilicity, and mesh size of the hydrogels increased while the elastic moduli decreased when increased the PEGDA MW or the content of higher MW PEGDA in the blends. Most of the hydrogels possessed excellent transparency in visible region. The viability of L929 cells on the surface of hydrogel was also estimated. All the selected hydrogels exhibited a relatively high proliferation rate, which demonstrated this hydrogel system with photoinitiator Irgacure819 had good biocompatibility. These results show the properties of PEGDA hydrogel could be easily adjusted by varying PEGDA MW or the ratios of low‐ and high‐MW macromers in the composites. It could be helpful for the design of proper PEGDA hydrogels in the applications as tissue engineering or drug delivery system. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of polylactic acid-lecithin-starch bioplastic film

Plastic-induced environmental issues could be solved using biomaterials, such as polylactic acid (PLA) film. PLA film is a costly solution suggesting the need to add less expensive starch. However, PLA and starch do not mix due to their diverging water behavior. In this study, we evaluated the impact of lecithin as a compatibilizer in varying ratio of PLA and starch film. The results show that inclusion of lecithin in PLA/starch composite leads to enhanced mechanical properties compared with the composite without lecithin. All films' thermal properties were stable but the thermograph of PLA/starch display two peaks whose distance is impacted by lecithin. In addition, morphology and functional group fingerprints revealed that the addition of lecithin improved the interfacial adhesion between the two polymers. Lecithin influenced the positioning and dispersion pattern of starch granules and distinct transmittance characteristics. The improved compatibility of PLA/starch makes the resulting films less susceptible to water penetration and dissolution. This work demonstrated the possibility of using lecithin as emulsifier between PLA and starch which could expand the application of PLA/starch film especially in packaging industries and bale net wrapping.     

An investigation study of gelatin release from semi‐interpenetrating polymeric network hydrogel patch for excision wound healing on Wistar rat model

Semi‐interpenetrating polymeric network hydrogel patches are fabricated using poly(acrylamide) (PAm) and gelatin (G) in which poly(caprolactone) diacrylate is used as a crosslinker for PAm while gelatin is kept uncrosslinked. The healing efficiency of selected hydrogel dressing [PAm₁G₁(0.5)] is evaluated in comparison with control group (cotton gauze covered with 3M Tegaderm?). The sustained release of gelatin is found to extend from 4 to 15 days while maximum tensile strength stretched to 559 ± 12.5 kPa in PAm₁G_0.5 matrix, which reduced to 158 ± 6.1 kPa at higher gelatin content (PAm₁G_1.0). The higher wound contraction (34%), less inflammatory response, significant improvement (P < 0.05) in the collagen biosynthesis, and the granulation tissue formation are observed in PAm/G treated animals in comparison to control, as evidenced by quantitative enhancement of DNA (21%), hydroxyproline (28%), and hexosamine (41%). The histological examination of PAm/G hydrogel treated wound tissues shows enhanced re‐epithelialization on day 8 and 12 post‐wounding, in comparison to control group. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42120.     

Centrifugally spun starch/polyvinyl alcohol ultrafine fibrous membrane as environmentally-friendly disposable nonwoven

We developed a new environmentally-friendly disposable nonwoven based on centrifugally spun ST/PVA ultrafine fibrous membrane in this research. The effects of ST/PVA ratio as well as formic acid post-treatment on thermal properties, tensile strength, and disposability of fibrous membranes were studied. To observe the morphology and chemical structures changing of fibers during fabrication and post-treatment, the obtained fibers were characterized by scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy. The fibrous membranes with uniform fiber diameters and excellent disposability properties were formed. The ST/PVA ratio of fibers was optimized according to the disposability and tensile strength of the fibrous membranes. Disintegration of untreated and post-treatment fibrous membrane with ST/PVA ratio of 3/1 was over 80% and 40%, respectively, and the tensile strength was improved over two times comparing with pure starch fibrous membrane.     

Synthesis and property of hydrogel membranes consisting of fumaramate with phosphorylcholine group

Fumaramate bearing a phosphoryl choline group, isopropyl‐2‐[2′‐(trimethylammonium) ethyl phosphoryl] ethyl fumaramate (IPTPFA), was radically copolymerized with 2‐hydroxyethylmethacrylate (HEMA) in the presence of various crosslinking agents, water, and 2,2′‐azobis(isobutyronitrile) to obtain hydrogel membranes. The obtained hydrogel membranes adsorbed bovine serum albumin (BSA) much less than those of poly(HEMA), and the values of water content (H) were higher than those of poly(HEMA). The values of tensile strength and tensile elongation of the hydrogel were 68.4 g/mm² and 239%, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2552–2557, 2004     

聚乙烯醇/天然橡胶共混物的制备及其性能研究

利用环氧化天然胶乳作为界面改性剂,采用胶乳共混法将聚乙烯醇（PVA）溶液同天然胶乳进行混溶,制备了PVA/天然橡胶（NR）的共混物,通过电子万能材料试验机、动态热机械分析仪、热老化箱和臭氧老化箱,研究了共混物力学性能、玻璃化转变温度、老化性能以及耐溶剂抽出性。结果表明,PVA的加入明显提高了NR的撕裂强度和硬度,而共混物的拉伸强度和断裂伸长率随着PVA含量的增加都出现下降的趋势;随着PVA含量的增加,NR的玻璃化转变温度呈现先增加后降低的趋势;随着PVA含量增加,共混物各试样对乙醇的耐抽出能力相差不大,对水的耐抽出能力逐步变弱。热空气老化对材料的力学性能影响明显,而臭氧老化由于时间较短,对材料的力学性能影响不明显。老化实验对材料的性能变化率影响显著。     

聚乙烯醇/淀粉共混材料研究进展

综述了近年来聚乙烯醇/淀粉共混材料的研究进展,主要介绍此类生物可降解性环境友好材料的制备方法,包括溶液流延法、挤出法以及模压法,以及增塑剂、交联剂、淀粉改性、纳米改性等对共混材料性能的影响,并对此类新材料的应用前景和发展方向进行了展望。     

羊毛粉/聚乙烯醇共混纤维的研究

采用添加还原剂、助溶剂、超声波振荡处理羊毛,制得直径小于2μm的羊毛粉,与聚乙烯醇共混进行湿法纺丝,制备羊毛粉/聚乙烯醇共混纤维,对共混纤维进行形态结构与性能研究。结果表明:羊毛粉/聚乙烯醇共混纤维截面趋于图形,无皮芯层,微孔结构致密;共混纤维的热性能较好,在234℃不分解;共混纤维强度约1.0 cN/dtex,随着羊毛粉含量增加,羊毛粉/聚乙烯醇共混纤维的强度和断裂伸长率下降,但回潮率增加。