Oil sorption behaviors of porous polydimethylsiloxane modified collagen fiber matrix

A facial and cost‐effective synthesis method of converting the leather protein solid wastes into a value‐added collagen matrix oil sorbent is successfully established for the first time. Hide powder fiber (HPF) was firstly prepared by using the pre‐tanned fleshing wastes from the leather industry, and then cross‐linked with epoxy‐terminated polydimethylsiloxane (PDMS) to produce hydrophobic collagen fiber, which was verified by the FT‐IR spectrum and contact angle analysis. Subsequently, a series of porous PDMS modified collagen‐based sorbents with roughness surface was successfully fabricated by solvent‐ and freeze‐drying methods respectively. The oil sorption capacity, sorption saturated time and retention capacity of the prepared sorbents was investigated. Combined with the SEM images, liquid displacement method and contact angle analysis, the results revealed that oil sorption capacities of the sorbent with lower pore size, higher porosity and rougher surface for silicone oil, motor oil and vegetable oil were approximate to 13.60, 12.50, and 11.92 g/g, respectively. Additionally, the sorption of oils is a quasi‐instantaneous process and also showed excellent oil retention capacity. It exhibited acceptable oil sorption performances as compared to commercial biomass sorbents. These findings indicated its potential as an eco‐friendly oil sorbent material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42727.     

Glutaraldehyde‐crosslinked chitosan/hydroxyapatite bone repair scaffold and its application as drug carrier for icariin

Chitosan/hydroxyapatite (CS/HA) bone repair scaffolds crosslinked by glutaraldehyde (GA) were prepared. Characterization of morphology, structure, mechanical property, and porosity of scaffolds were evaluated. The influences of CS viscosity, HA content, and crosslinking degree on properties of scaffolds were discussed. SEM images showed that CS/HA scaffolds were porous with short rod‐like HA particles dispersing evenly in CS substrate. When [η]_CS = 5.75 × 10^?4, HA content = 65%, and crosslinking degree = 10%, the resulting CS/HA scaffolds had a flexural strength of 20 MPa and porosity of 60%, which could meet the requirements of bone repair materials. The scaffolds were used as drug carriers for icariin, and the impacts of loading time and crosslinking degree of scaffolds on drug‐loading dose were discussed. The suitable loading time was 24 h and it would be better to keep crosslinking degree no more than 10%. The drug release behavior demonstrated that the icariin‐loading CS/HA scaffolds could achieve basic drug sustained release effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1539–1547, 2013     

Chitosan/gelatin porous bone scaffolds made by crosslinking treatment and freeze‐drying technology: Effects of crosslinking durations on the porous structure,compressive strength,and in vitro cytotoxicity

In this study, freezing was used to separate a solute (polymer) and solvent (deionized water). The polymer in the ice crystals was then crosslinked with solvents, and this diminished the linear pores to form a porous structure. Gelatin and chitosan were blended and frozen, after which crosslinking agents were added, and the whole was frozen again and then freeze‐dried to form chitosan/gelatin porous bone scaffolds. Stereomicroscopy, scanning electron microscopy, compressive strength testing, porosity testing, in vitro biocompatibility, and cytotoxicity were used to evaluate the properties of the bone scaffolds. The test results show that both crosslinking agents, glutaraldehyde (GA) and 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide, were able to form a porous structure. In addition, the compressive strength increased as a result of the increased crosslinking time. However, the porosity and cell viability were not correlated with the crosslinking times. The optimal porous and interconnected pore structure occurred when the bone scaffolds were crosslinked with GA for 20 min. It was proven that crosslinking the frozen polymers successfully resulted in a division of the linear pores, and this resulted in interconnected multiple pores and a compressively strong structure. The 48‐h cytotoxicity did not affect the cell viability. This study successfully produced chitosan/gelatin porous materials for biomaterials application. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41851.     

Variation of pore structure of organosilicone‐modified skin collagen matrix

The pore structure of skin collagen matrix modified by organosilicone alone, combination of organosilicone and chromium respectively, was investigated mainly through nitrogen adsorption, scanning electron microscopy and fractal analysis. The results indicated that increasing the dosage of organosilicone endowed more numbers of uniform smaller pores, increased porosity in modified collagen matrix and improved thermal stability verified by differential scanning calorimeter analysis. A similar trend was observed after incorporating less amount of chromium to organosilicone modification in the process. It can be presumed that a rigid and stable three‐dimensional silica network structure formed in the interior of the collagen fiber plays a role in fixing the collagen molecular chain, conferring improved hydrothermal stability to the skin matrix. The findings are of great significance to explore chrome‐less and further chrome‐free silicone tanning technology, and are helpful to promote sustainable development of the leather industry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44831.     

Morphology of crosslinked hyaluronic acid porous hydrogels

Hydrogels, based on hyaluronic acid or hyaluronan (HA), are gaining attention as possible cell‐scaffolding materials for the regeneration of a variety of tissues. This article describes how HA, a naturally occurring polymer, has been crosslinked to reduce its degradation rate and freeze dried to produce porous materials suitable for tissue engineering. The resulting pore architecture has been assessed as a function of freezing temperature and freezing rate, type of crosslinkers, and methods used in the crosslinking process. On comparing the average densities of crosslinked and uncrosslinked scaffolds, it is apparent that the chemical modification increases sponge density and wall thickness of the pores while decreasing the pore size. The mechanical response of the modified materials has been investigated by equilibrium‐swelling measurements and compression tests. These materials have an average pore size ranging from 167 to 215 μm, which suggests that they would be a suitable temporary site for cell proliferation. The materials exhibit moderate mechanical integrity and are expected to be capable of withstanding physiological stresses in vivo. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Biocompatible scaffolds composed of chemically crosslinked chitosan and gelatin for tissue engineering

Chitosan‐based scaffolds are widely studied in tissue regeneration because of their biocompatibility and biodegradability. Scaffolds are obtained by different techniques and can be modified with other polymers allowing controlling their properties. This article discusses the assembling of three‐dimensional chitosan porous scaffolds blended with gelatin. Gelatin was used to enhance cells attachment due to the presence of cell adhesion motifs, while improving mechanical strength. 2,5‐dimethoxy‐2,5‐dihydrofurane (DHF) was used as the crosslinking agent, because it allowed to control the reaction kinetics through temperature, time and DHF concentration. The results indicate that scaffolds morphology, pore sizes and distribution, compressive moduli and biodegradation in vitro with lysozyme, can be customized with variations of gelatin content and crosslinking degree. Scaffolds were neither cytotoxic nor genotoxic for human keratinocytes, exhibiting cell–substrate interactions. Our findings demonstrated that chitosan–gelatin scaffolds crosslinked with DHF, as a new crosslinking agent, are suitable in tissue engineering applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43814.     

Biocompatible,stimuli‐responsive hydrogel of chemically crosslinked β‐cyclodextrin as amoxicillin carrier

A novel pH‐responsive, chemically crosslinked hydrogelator (cl‐β‐CD/pVP) has been fabricated using β‐cyclodextrin (β‐CD) and N‐vinyl pyrollidone (N‐VP) in presence of diurethane dimethacrylate (DUDMA) crosslinker/azobisisobutyronitrile initiator through free radical polymerization. Various grades of cl‐β‐CD/pVP have been synthesized and the best grade has been considered with higher crosslinking density, higher gel strength, and lower % swelling ratio. The hydrogelator has been characterized by FTIR, ¹H and ¹³C NMR spectroscopy, TGA, and FESEM analyses. The hydrogelator demonstrates pH‐responsive behavior, which has been confirmed by swelling behavior and gel characteristics at various pH (at 37 °C). Using hen egg lysozyme, degradation experiment has been performed, which confirms the biodegradable nature of the hydrogel. The in vitro cytotoxicity study and live–dead assay suggest that the hydrogelator is cytocompatible toward MG‐63 cells. Finally, the hydrogelator shows excellent efficacy as an antibiotic (amoxicillin) carrier. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45939.     

Effect of montmorillonite on the rheological properties of dually crosslinked guar gum‐based hydrogels

One strategy to create chemical and physical cross‐links simultaneously is to introduce into the chemical network hydrogen bonding with clay nanofillers. Understanding the relaxation mechanisms of these systems is crucially important and has drawn the extensive interest of many scientists. In this work, the influence of different amounts of montmorillonite on the structural and rheological properties of guar gum hydrogels was investigated. Depending on the clay content, different nanostructures were identified by X‐ray diffraction (XRD) and their effect on the rheological properties of the dual hydrogels was studied. From stress and frequency sweep tests it emerged that all the samples exhibit a weak gel behavior and showed a maximum for G″ that can be ascribed to the breaking and reforming of transient physical crosslinks. This relaxation mode is more pronounced for the hydrogel for which a minimum in the swelling degree was observed. On the basis of these results, a model structure was proposed according to which the clay sheets act as effective multifunctional cross‐linkers. The more homogeneously dispersed are the clay platelets, the higher is the density of physical crosslinks. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41373.     

Porous elastomeric beads from crosslinked emulsions

The production of porous polymeric particles is attractive for a large number of applications and can be achieved by various techniques. Although numerous production schemes exist for glassy polymers, difficulties arise for soft, rubbery materials that need a chemical crosslinking step, such as elastomers. This is particularly true for poly(dimethylsiloxane) (PDMS), which shows the lowest glass‐transition temperature among the polymers. Recent studies suggest in situ hydrogen bubble formation or vacuum drying of water droplets dispersed in the polymer matrix in order to generate porous PDMS structures. In this work we report early results based on the chemical crosslinking of water in PDMS emulsion droplets in a mechanically stirred thermostated water vessel. This approach is shown to lead to high porosity PDMS beads (ca. 10^?3 m particle diameter) with an open structure whose properties (diameter and porosity) are strongly influenced by the starting composition (solvent, surfactant, and polymer types and ratios), as well as the operating parameters (agitation and temperature). The possible uses of these derived beads are discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 967–971, 2002     

The effect of BMP‐2 and VEGF loading of gelatin‐pectin‐BCP scaffolds to enhance osteoblast proliferation

A composite scaffold of gelatine (Gel)‐pectin (Pec)‐biphasic calcium phosphate (BCP) was successfully fabricated. Growth factors such as bone morphogenetic protein‐2 (BMP‐2) and vascular endothelial growth factor (VEGF) were loaded into the Gel‐Pec‐BCP hydrogel scaffolds by freeze‐drying. The surface morphology was investigated by scanning electron microscopy, and BCP dispersion in the hydrogel scaffolds was measured by energy dispersive and X‐ray diffraction spectroscopy. The results obtained from Fourier transform infrared spectroscopy and quantitative measurements showed successfully loading of BMP‐2 and VEGF into the Gel‐Pec‐BCP hydrogel scaffolds. In addition MC3T3‐E1 preosteoblasts were cultivated on the three types of scaffolds to investigate the effects of BMP‐2 and VEGF on cell viability and proliferation. The Gel‐Pec‐BCP scaffolds loaded with VEGF and BMP‐2 demonstrated more cell spreading and proliferation compared to those of the Gel‐Pec‐BCP scaffolds. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41241.     

Facile fabrication of near-infrared light-responsive shape memory nanocomposite scaffolds with hierarchical porous structures

In this work, the near-infrared (NIR) light-responsive shape memory scaffolds with hierarchical porous structures are designed and facilely formed by freeze drying of 3D printed viscous gel-like pickering emulsions, which are stabilized by hydrophobically modified graphene oxide (g-GO) and silica nanoparticles, and contain thermo-responsive poly(d , l -lactic acid-co-trimethylene carbonate) (PLMC) in the oil phase. The prepared scaffolds display an interconnected filament structure with hierarchical pores and high porosity. The incorporation of g-GO nanoparticles into PLMC matrix prompts that the scaffold shape memory can be triggered by NIR light with fast shape recovery. Moreover, the in vitro mineralization experiment shows that the scaffolds have biological activity, and the drug release study demonstrates that the scaffolds can be used as drug carriers with efficient drug release capacity. Furthermore, cell culture assays based on mouse bone mesenchymal stem cells exhibit that the scaffolds own good cytocompatibility. Therefore, the facile preparation and remote activation of the shape memory nanocomposite scaffolds with hierarchical porous structure and multifunctionality represents a highly attractive candidate as minimally invasive implantation scaffolds for bone tissue engineering applications.     

Silk fibroin‐chondroitin sulfate‐alginate porous scaffolds: Structural properties and in vitro studies

The development of porous biodegradable scaffolds is of great interest in tissue engineering. In this regard, exploration of novel biocompatible materials is needed. Silk fibroin‐chondroitin sulfate‐sodium alginate (SF‐CHS‐SA) porous hybrid scaffolds were successfully prepared via lyophilization method and crosslinked by 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide‐ethanol treatment. According to the scanning electron microscopy studies, mean pore diameters of the scaffolds were in the range of 60–187 μm. The porosity percentage of the scaffold with SF‐CHS‐SA ratio of 70 : 15 : 15 (w/w/w %) was 92.4 ± 3%. Attenuated total reflectance Fourier transform infrared spectroscopy, X‐ray diffraction, and differential scanning calorimetry results confirmed the transition from amorphous random coil to crystalline β‐sheet in treated SF‐CHS‐SA scaffold. Compressive modulus was significantly improved in hybrid scaffold with SF‐CHS‐SA ratio of 70 : 15 : 15 (3.35 ± 0.15 MPa). Cytotoxicity assay showed that the scaffolds have no toxic effects on chondrocytes. Attachment of chondrocytes was much more improved within the SF‐CHS‐SA hybrid scaffold. Real‐time polymerase chain reaction analyses showed a significant increase in gene expression of collagen type II, aggrecan, and SOX9 and decrease in gene expression of collagen type I for SF‐CHS‐SA compared with SF scaffold. This novel hybrid scaffold can be a good candidate to be utilized as an efficient scaffold for cartilage tissue engineering. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41048.     

Preparation and properties of crosslinked network coatings based on perfluoropolyether/poly(dimethyl siloxane)/acrylic polyols for marine fouling–release applications

α,ω‐Triethoxysilane terminated poly(dimethyl siloxane) (PDMS) oligomer, α,ω‐triethoxysilane terminated perfluoropolyether (PFPE) oligomer, and acrylic polyols were first synthesized via an addition reaction and free‐radical polymerization. Then, crosslinked network coatings based on PFPE/PDMS/acrylic polyols for marine fouling‐release applications were prepared by a condensation reaction. The structure of the crosslinked network coating was characterized by Fourier transform infrared spectroscopy. The chemical composition of the coating surface was characterized by X‐ray photoelectron spectroscopy. The thermal properties, surface energy, mechanical properties, adhesion, and antiseawater immersion performance of the coatings were systematically studied. The antibiofouling properties of the crosslinked network coating were evaluated by laboratory biofouling assays with the bacteria Escherichia coli and the fouling diatom Navicula. The results from the preliminary study suggested that this crosslinked network coating had good adhesion and promising antifouling properties that were comparable to a silicone standard. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41860.     

Influence of particle size and fluid fraction on rheological and extrusion properties of crosslinked hyaluronic acid hydrogel dispersions

Crosslinked hyaluronic acid (HA) hydrogels are widely used in gel/HA fluid formulations as a viscosupplement to treat joint diseases; thus, it is important to characterize these hydrogels in terms of their particle size and to investigate the effects of the gel/fluid mixtures on their rheological properties and extrusion force. Hydrogels previously crosslinked with divinyl sulfone were sheared in an Ultra‐Turrax unit to produce particles with mean diameters ranging from 20 to 200 μm. Hydrogels with 75–100 μm mean diameters were also evaluated in dispersions containing a 20–40% mass fraction of HA fluid. The mean diameters were measured by laser light scattering and the rheological behavior was determined by oscillatory and steady measurements in parallel plate geometry. The HA hydrogels exhibited the typical behavior of so‐called weak gels, as analyzed by the storage and loss moduli G′ and G″, respectively. The viscoelasticity, the viscosity, and the extrusion force increased with the hydrogel particle size. The fluid phase dispersions decreased both moduli. At 40% fluid fraction, the gel characteristics were lost and the dispersion behaved as a fluid. Based on these results, the particle size and HA fluid fraction in hydrogel dispersions may be optimized to develop more efficient viscosupplement formulations. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Active layer modification of commercial nanofiltration membrane using CuBTC/PVA matrix for improved surface and separation characteristics

The present study proposes a facile route for the modification of commercial nanofiltration (NF) polymeric membrane by embedding metal organic framework (MOF) via dip coating. A mixed membrane matrix comprising of copper benzene-1,3,5-tricarboxylate (CuBTC) and polyvinyl alcohol (PVA) served as the new active layer. The obtained topography, functional group, and surface elemental analysis elucidated the presence of heterogeneous phase and the distribution of the MOF on the membrane. The dip coating well supported the modification through excellent adhesion. The water wettability of the modified membrane displayed a positive correlation with CuBTC loading in the PVA polymer matrix. Permeation and separation characteristics of the resultant membranes were investigated by retaining protein and carbohydrates from synthetic dairy wastewater (SDWW). The permeability rate of modified samples increased to 43% as compared to the commercial NF membrane. A significant improvement in the rejection rate of carbohydrate from 61% to 87% and protein from 88% to 94% was achieved. Membrane Fouling was found to be much lesser for the modified samples. The study highlights the potential of CuBTC as filler material for enhancing the separation characteristic of established NF membrane.     

Gellan–adipic acid blends crosslinked by means of a dehydrothermal treatment

Blends of gellan gum (GE) and adipic acid (ADA), at various ratios, were manufactured in the form of films by casting from aqueous solutions and crosslinked by a dehydrothermal treatment (DHT). The materials, before and after DHT, were characterized by both physicochemical tests and cellular adhesion and growth on the film surfaces. The total reflection and spotlight Fourier transform infrared (FTIR) spectroscopy and optical and scanning electron microscopy showed the presence of both GE‐rich and ADA‐rich regions and the formation of ester groups after DHT. Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis (DMA) showed that the crosslinking by DHT made the materials more thermally stable. The swelling in water, which diminished in the films subjected to DHT, confirmed that the crosslinking enhanced the whole stability of the material. DMA also showed that the behavior of the GE–ADA blends was quite similar to that of some living tissues, such as the skin. The cell cultures indicated that the materials, especially that with a 6 : 10 ADA‐to‐GE ratio, were very able to promote cellular adhesion and proliferation. In conclusion, the GE–ADA crosslinked blends appeared very suitable for a use as biomaterials; in particular, the cell cultures indicated that they might be useful as scaffolds for tissue reconstruction. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comparison of rigid divinylbenzene with flexible 1,7‐octadiene crosslinks in acrylic acid resins—effects on kinetics of swelling and loading of heavy metal ions from water

Acrylic acid–1,7‐octadiene resin was synthesized in beaded form by a two‐step process: suspension polymerization of ethylacrylate and 1,7‐octadiene monomers, followed by hydrolysis using either 98% H₂SO₄ or 10 M NaOH. Acrylic acid–divinylbenzene resins were also synthesized by the same process for the purpose of comparing a rigid divinylbenzene with a flexible 1,7‐octadiene crosslinkage in the acrylic acid resins. Swelling of the resins in distilled water shows that replacing divinylbenzenes with 1,7‐octadiene makes the resin achieve greater swelling in a significantly shorter time. 1,7‐Octadiene also allowed for an increase in crosslinkage to 20% compared to 4% in the case of divinylbenzene, without compromising the loading rates of toxic heavy metal ions like Pb²⁺, Cu²⁺, and Cr³⁺ from water samples. The acrylic acid–1,7‐octadine resin was found useful for removal of the toxic heavy metal ions from wastewater samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41038.     

The formation of the S‐shaped edge‐on lamellae on the thin porous polylactic acid membrane via phase separation induced by water microdroplets

Biodegradable polymers have received increased attention due to their potential application in the medicine and food industries; in particular, poly(lactic acid) (PLA) is a primary biopolymer because of its excellent biocompatibility and absorbability features. In this study, a porous PLA membrane was fabricated by phase separation using water microdroplets produced by an ultrasonic atomizer as a coagulation bath. The formation of S‐type clusters was attributed to the slow exchange rate between solvent and coagulant, which provided time for the movement of polymer molecules. The effect of preparation conditions on the structure of S‐type clusters, including polymer concentration in solution and ambient temperature was investigated. The PLA porous membrane prepared from water micro‐droplets with different morphology compared with the sample fabricated from distilled water has potential application in fields of tissue engineering and artificial organ generation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43355.     

Preparation and characterization of castor oil‐based waterborne polyurethane crosslinked with 2‐amino‐2‐(hydroxymethyl)‐1,3‐propanediol

Crosslinked castor oil (CO)‐based waterborne polyurethane was synthesized from CO, polycarbonate diol, isophorone diisocyanate, 2,2‐dimethylol propionic acid, and 2‐amino‐2‐(hydroxymethyl)‐1,3‐propanediol (THAM) using pre‐polymer process. Fourier transform infrared spectroscopy, X‐ray diffraction, and transmission electron microscopy were utilized to characterize the above‐synthesized polyurethane. The effect of THAM content was studied on particle size, zeta potential, thermogravimetric analysis, differential scanning calorimetry, tensile tests, and contact angle measurement. Results showed that, with the increase of THAM content, the particle size increases and the thermal stability increases. Furthermore, as the THAM content increased from 0% to 1.5%, tensile strength increased from 9.5 to 16.3 MPa, contact angle increased from 67.8° to 87.4°, and bibulous rate decreased from 13.4% to 6.1%, the elongation at break dropped from 154.8% to 37.9%, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45532.     

Mechanical behavior,microstructure and thermooxidation properties of sequentially crosslinked ultrahigh molecular weight polyethylenes

The aim of this study was to explore the impact of the sequential irradiation and annealing process on the microstructure, thermooxidation behavior and mechanical properties of GUR 1050 ultrahigh molecular weight polyethylene (UHMWPE) with respect to the postirradiation annealed material. For this purpose, the effects of a variety of irradiation and annealing conditions on microstructure and mechanical properties were investigated. Differential scanning calorimetry was performed to characterize melting temperature, crystalline content and crystal thickness, whereas transmission electron microscopy provided additional insights into crystal morphology. Thermogravimetric experiments in air served to assess thermooxidation resistance and changes associated to radiation‐induced crosslinking. Fatigue properties were studied from three different approaches, namely short‐term cyclic stress–strain tests, long‐term fatigue experiments and crack propagation behavior. Likewise, three experimental techniques (uniaxial tensile test, impact experiments, and load to fracture of compact tension specimens) allowed evaluation of the fracture resistance. The present findings confirm sequentially crosslinked UHMWPE exhibited improved thermooxidation resistance and thermal stability compared to post‐irradiation annealed UHMWPE. Also, the mechanical behavior, including the fatigue and fracture resistance, of these materials was generally comparable regardless of the annealing strategy. Therefore, the sequential irradiation and annealing process might provide higher oxidation resistance, but not a significant improvement in mechanical properties compared to the single radiation dose and subsequent annealing procedure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013