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.     

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.     

Soluble‐eggshell‐membrane‐protein‐modified porous silk fibroin scaffolds with enhanced cell adhesion and proliferation properties

In this study, a porous silk fibroin (SF) scaffold was modified with soluble eggshell membrane protein (SEP) with the aim of improving the cell affinity properties of the scaffold for tissue regeneration. The pore size and porosity of the prepared scaffold were in the ranges 200–300 μm and 85–90%, respectively. The existence of SEP on the scaffold surface and the structural and thermal stability were confirmed by energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The cell culture study indicated a significant improvement in the cell adhesion and proliferation of mesenchymal stem cells (MSCs) on the SF scaffold modified with SEP. The cytocompatibility of the SEP‐conjugated SF scaffold was confirmed by a 3‐(4,5‐dimethyltriazol‐2‐y1)‐2,5‐diphenyl tetrazolium assay. Thus, this study demonstrated that the biomimic properties of the scaffold could be enhanced by surface modification with SEP. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40138.     

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     

Development of gelatin/chitosan/PVA hydrogels: Thermal stability,water state,viscoelasticity, and cytotoxicity assays

Gelatin/chitosan/poly(vinyl alcohol) (PVA) hydrogels were fabricated with different polymer ratio using the freeze-drying process. The thermal stability, water state, rheological, and cytotoxic properties of the hydrogels were evaluated. Thermogravimetric/differential scanning calorimetry analyses showed a decomposition onset temperature below 242.7 ± 2.7 °C. The samples did not show statistical differences (p < 0.05) on the onset temperature values. Nonfreezing water reached a constant value around of 1 g water/g polymer. Freezing water increased linearly with the increase of the water content independently of the polymer ratio. The hydrogels showed an equilibrium water content from 9 to 13 times their mass. The hydrogels exhibited a solid-viscoelastic behavior. The elastic modulus was higher with the increase of chitosan concentration (G′ = 22 170 ± 85 Pa) independently of the temperature (5–55 °C). In vitro assay showed that hydrogels are nontoxic in the HT29-MTX-E12 cell line. These results indicate that the gelatin/chitosan/PVA hydrogels could be considered for biomedical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47149.     

Effects of micro and nano β‐TCP fillers in freeze‐gelled chitosan scaffolds for bone tissue engineering

Tissue engineering holds an exciting promise in providing a long‐term cure to bone‐related defects and diseases. However, one of the most important prerequisites for bone tissue engineering is an ideal platform that can aid tissue genesis by having biomimetic, mechanostable, and cytocompatible characteristics. Chitosan (CS) was chosen as the base polymer to incorporate filler, namely beta‐tri calcium phosphate (β‐TCP). This research deals with a comparative study on the properties of CS scaffolds prepared using micro‐ and nano‐sized β‐TCP as filler by freeze gelation method. The scaffolds were characterized for their morphology, porosity, swelling, structural, chemical, biodegradation, and bioresorption properties. Rheological behavior of polymer and polymer‐ceramic composite suspensions were analyzed and all the suspensions with varying ratios of β‐TCP showed non‐Newtonian behavior with shear thinning property. Pore size, porosity of micro‐ and nano‐sized composite scaffolds are measured as 48–158 μm and 77% and 43–155 μm and 81%, respectively. The scaffolds containing nano β‐TCP possess higher compressive strength (～2.67 MPa) and slower degradation rate as compared to composites prepared with micro‐sized β‐TCP (～1.52 MPa). Bioresorbability, in vitro cell viability by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, proliferation by Alamar blue assay, cell interaction by scanning electron microscope, and florescence microscopy further validates the potentiality of freeze‐gelled CS/β‐TCP composite scaffolds for bone tissue engineering applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41025.     

Modulating stability and mechanical properties of silica–gelatin hybrid by incorporating epoxy‐terminated polydimethylsiloxane oligomer

Silica‐gelatin hybrids, particularly GT‐G hybrids prepared by crosslinking gelatin (G) with γ‐glycidoxypropyltrimethoxysilane (GT), have attracted much attention in tissue engineering for diverse applications in hard or soft tissue regeneration; however, scaffolds with tunable properties are needed to meet specific requirements. In this work, a silica‐gelatin hybrid (ES/GT‐G) was synthesized by incorporating epoxy‐terminated polydimethylsiloxane oligomer (ES) to modulate the properties of GT‐G hybrid. The ES/GT‐G hybrid sponge presented a 3D network structure with porosity 86.4% ± 0.9%, determined by the liquid displacement method, and average pore size 340 ± 36 μm, determined by SEM observation. Compared with GT‐G hybrid material, the prepared ES/GT‐G hybrid wet film showed a decrease of tensile strength from 2.79 ± 0.04 MPa to 1.87 ± 0.12 MPa, with an increase of elongation at break from 19.96 ± 0.66% to 29.86 ± 0.87%, and the ES/GT‐G hybrid sponge exhibited a decline of compressive yield strength from 1.21 ± 0.04 MPa to 0.72 ± 0.06 MPa, based on the tensile and compression tests respectively. The introduction of ES enhanced the thermal denaturing temperature of GT‐G by 5°C as determined by a DSC study, and increased in vitro biodegradation slightly, without significantly changing surface wettability and swelling behavior. These findings suggest that silica‐gelatin hybrids with tunable properties are promising for applications from hard to soft tissue regeneration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43059.     

The inclusion of fetal bovine serum in gelatin/PCL electrospun scaffolds reduces short‐term osmotic stress in HEK 293 cells caused by scaffold components

Components of gelatin/polycaprolactone (PCL) electrospun scaffolds are released to surrounding media and cause osmotic changes that adversely affect cell viability and proliferation. In this study, the physiological properties of gelatin/PCL scaffolds were investigated by qRT‐PCR and by performing cellular studies on HEK 293 cells. Components released from gelatin/PCL scaffolds were found to induce osmotic stress response in these cells. However, osmotic stress was inhibited by adding fetal bovine serum (FBS) to scaffolds. In addition, focal adhesion related genes were found to be up‐regulated in HEK 293 cells on gelatin/PCL/20% FBS scaffolds, and this induced the down‐regulations of cell‐death related genes. Furthermore, the inclusion of 20% FBS improved the viabilities of HEK 293 cells on gelatin/PCL scaffolds. This study indicates that adding FBS to gelatin/PCL scaffolds improves scaffold bio‐affinity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synergistic effects of crosslinking and chitosan molecular weight on the microstructure,molecular mobility,thermal and sorption properties of porous chitosan/gelatin/hyaluronic acid scaffolds

In this study, synergistic effects of crosslinking and chitosan molecular weight on the microstructure, molecular mobility, thermal, and sorption properties of porous chitosan/gelatin/hyaluronic acid hybrid foams are reported. Fourier transform infrared spectroscopy has been utilized to confirm the covalent attachment of hyaluronic acid to gelatin and chitosan, and covalent chemical crosslinking between gelatin and chitosan. Detailed image analysis of scanning electron microscopy images of the porous scaffold hydrids reveal that the pore size of the materials formulated using either low‐ or high‐molecular‐weight chitosan increases significantly upon crosslinking using ethyl(dimethylaminopropyl) carbodiimide/N‐Hydroxysuccinimide. These microstructural changes are even more pronounced for the crosslinked hybrid scaffolds formulated using low‐molecular‐weight chitosan, highlighting a synergistic effect between crosslinking and the use of low‐molecular‐weight chitosan. Results obtained using differential scanning calorimetry demonstrate a significant reduction in molecular mobility reduction in molecular mobility for crosslinked scaffolds formed using high‐molecular‐weight chitosan compared to non‐crosslinked hybrids and crosslinked hybrids formulated using low‐molecular‐weight chitosan. Correspondingly, dynamic vapor sorption evidenced significantly lower water vapor sorption for crosslinked scaffolds formulated using high‐molecular‐weight chitosan. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44772.     

Controlled freezing and freeze drying: a versatile route for porous and micro‐/nano‐structured materials

Freeze drying is a process whereby solutions are frozen in a cold bath and then the frozen solvents are removed via sublimation under vacuum, leading to formation of porous structures. Pore size, pore volume and pore morphology are dependent on variables such as freeze temperature, solution concentration, nature of solvent and solute, and the control of the freeze direction. Aqueous solutions, organic solutions, colloidal suspensions, and supercritical CO₂ solutions have been investigated to produce a wide range of porous and particulate structures. Emulsions have recently been employed in the freeze drying process, which can exert a systematic control on pore morphology and pore volume and can also lead to the preparation of organic micro‐ and nano‐particles. Spray freezing and directional freezing have been developed to form porous particles and aligned porous materials. This review describes the principles, latest progress and applications of materials prepared by controlled freezing and freeze drying. First of all the basics of freeze drying and the theory of freezing are discussed. Then the materials fabricated by controlled freezing and freeze drying are reviewed based on their morphologies: porous structures, microwires and nanowires, and microparticles and nanoparticles. The review concludes with new developments in this area and a brief look into the future. Copyright © 2010 Society of Chemical Industry     

Core–shell PVA/gelatin nanofibrous scaffolds using co‐solvent,aqueous electrospinning: Toward a green approach

Electrospinning (ES) of gelatin often requires cytotoxic organic solvents or acidic environments, which deteriorate cell recognition sites. In this study, aqueous, non‐toxic, co‐solvent ES was performed to obtain core–shell poly(vinyl alcohol) (PVA)/gelatin nanofiber scaffolds. Effects of the core/shell feed rate ratio (FRR) were investigated on a morphological and mechanical basis. PVA:gelatin ratio of 1:4 was the limiting ratio for specific voltage and electrode distance parameters to obtain uniform fibers. Core–shell bead‐free structures were obtained at 8% PVA and gelatin aqueous solutions. A mean diameter of 280 nm was obtained for 1:1 FRR at 15 kV and 15 cm of electrode distance. Crosslinking resulted in slight improvement in tensile strengths and severe decrease in ductility. Fourier transform infrared spectra revealed retention and improvement of stable secondary structures of gelatin after ES. The scaffolds almost degraded more than 60% in 14 days. Based on the results, present scaffolds hold great promise as suitable candidates for biomedical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46582.     

Radiation‐induced crosslinking of acetylene‐impregnated polyesters. II. Effects of preirradiation crystallinity,molecular structure,and postirradiation crosslinking on mechanical properties

Electron beam‐irradiated crosslinking has been studied in a series of acetylene‐impregnated polyesters and amorphous copolyesters, including poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(cyclohexane dimethylene terephthalate) (PCDT), and poly(cyclohexane dimethylene terephthalate‐co‐ethylene terephthalate) (P(CDT‐co‐ET)) having 29 and 60 wt % ethylene terephthalate (ET). The extent of crosslinking was observed by gel fraction measurements and was found to be significantly influenced by the aliphatic chain content of the polyesters (PET < PBT < PCDT). In addition, as the preirradiation crystallinity of the polyesters was reduced, the extent of acetylene‐enhanced crosslinking was greatly raised. Decreases in the postirradiation crystalline melting temperature and degree of crystallinity were observed in all the polyesters, using differential scanning calorimetry measurements. Particularly significant findings have been the shift in the glass‐transition temperatures (Tg) to higher temperatures and the decrease in loss tangents at higher temperatures, both of which confirm that crosslinking has taken place. The storage moduli (E′) in the rubbery plateau region of PCDT and P(CDT‐co‐ET) were significantly affected by irradiation dose. Increased network tightness in postirradiated PBT and PCDT films was also inferred from melt‐rheology measurements, in which stress relaxed more slowly following a stepped strain. Improvements in the mechanical properties of the irradiated polyesters and copolyesters were clearly evidenced by the increased modulus at higher temperatures, observed using dynamic mechanical thermal analysis and melt‐rheology methods. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4476–4490, 2006     

Characterization of multiwalled carbon nanotube filled,palm‐oil‐based polyalkyds: Effects of loading and in situ reaction

In this study, the contribution of multiwalled carbon nanotubes (MWCNTs) was studied for the evaluation of the performances of polyalkyd‐based films produced from dehydrated palm oil. Initially, different percentages of MWCNTs, including 0.5, 1.0, and 1.5 wt %, were considered for loading into the resin with the help of sonication. Additionally, a 1.0 wt % loading was considered for in situ conditions during the esterification process to achieve better dispersion and obtain improved properties of the film. The loading was evaluated by different performance tests, such as those of tensile, elongation, pencil hardness, swelling ratio, gel content, wettability, chemical resistivity, adhesion, and surface morphology. The results of mechanical testing showed that the addition of 1.0 wt % MWCNTs enhanced the tensile strength by 50%, whereas in situ conditions were found to be favorable for significantly improving the tensile strength by 75%. Moreover, the wettability, surface morphology, and thermal properties were also found to be in favor of in situ conditions for the dispersion of the MWCNTs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42934.     

Preparation of porous poly(D,L‐lactide) and poly(D,L‐lactide‐co‐glycolide) membranes by a phase inversion process and investigation of their morphological changes as cell culture scaffolds

Porous membranes composed of the biodegradable polyesters poly(D,L ‐lactide) (PLA) and poly(D,L ‐lactide‐co‐glycolide) (PLGA) were prepared by a phase inversion process. The molecular weights of the polymers and the concentrations of the polymer solutions affected the pore size and structure of the PLA and PLGA membranes. The molecular weights and morphological changes of the membranes as a function of time were investigated under incubation at 37°C in a humidified 5% CO₂ atmosphere. The pores that formed in the membranes changed dramatically with increasing time under these conditions. From the thermal characterization of the polymers in their dry and wet states, we found that the glass‐transition temperatures of PLA and PLGA affected morphological structure changes in the porous membranes. We also prepared a collagen‐coated membrane to improve the interaction between the cell and the substrate, and we observed that the collagen coating enhanced the attachment and growth of Chinese hamster ovary cells on the substrate. Finally, we found that only PLA was a suitable material to prepare a porous membrane scaffold with the phase inversion process with PLA, and a collagen coating was necessary for cell culture on the membrane. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2082–2092, 2004     

Two‐stage drawing process to prepare high‐strength and porous ultrahigh‐molecular‐weight polyethylene fibers: Cold drawing and hot drawing

High‐strength and porous ultrahigh‐molecular‐weight polyethylene (UHMWPE) fibers have been prepared through a two‐stage drawing process. Combined with tensile testing, scanning electron microscopy, and small‐angle X‐ray scattering, the mechanical properties, porosity, and microstructural evolution of the UHMWPE fibers were investigated. The first‐stage cold drawing of the gel‐spun fibers and subsequent extraction process produced fibers with oriented lamellae stacks on the surface and plentiful voids inside but with poor mechanical properties. The second‐stage hot drawing of the extracted fibers significantly improved the mechanical properties of the porous fibers because of the formation of lamellar backbone networks on the surface and microfibrillar networks interwoven inside to support the voids. With various processing conditions, the optimized mechanical properties and porosity of the prepared UHMWPE fibers were obtained a tensile strength of 1.31 GPa, a modulus of 10.1 GPa, and a porosity of 35%. In addition, a molecular schematic diagram is proposed to describe structural development under two‐stage drawing, including void formation and lamellar evolution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42823.     

Effects of pore morphology and size on antimicrobial activity of chitosan/poly(ethylene glycol) diacrylate macromer semi‐IPN hydrogels

The objective of this study was to obtain antibacterial active chitosan/poly(ethylene glycol) diacrylate macromere (CS/PEGM) semi‐IPN hydrogels near a neutral pH level by changing their pore size and morphology. These hydrogels were prepared from CS and PEGM with different molecular weights in the presence of pore‐forming agents, poly (ethylene glycol) (PEG) or sodium bicarbonate (NaHCO₃), by using two different initiator system, namely chemical or UV. A combination of CS with PEG or NaHCO₃ in the presence of PEGM could be able to create desired pore formation in both initiator systems. The antibacterial activity of hydrogels changed with the molecular weight (g/mol) of PEGM in the order 2000>400>8000. A chemical initiation system was found more suitable than the UV initiation system for antibacterial activity. Hydrogels showing the highest antibacterial activity on Staphylococcus aureus and Escherichia coli have medium or distributed pore size and interconnected pores. Hydrogels prepared with PEGM (M_n: 2000 g/mol) were proposed for antibacterial wound dressing and soft tissue regeneration applications owing to their antibacterial activity and elastic modulus. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42707.     

Synthesis and characterization of nonionic 1‐vinyl‐2‐pyrrolidinone/methacryloxy silicone copolymers: Effects of molecular weight of silicone and crosslinking density

Nonionic 1‐vinyl‐2‐pyrrolidinone/methacryloxy silicone copolymers (VP/VS copolymers) were prepared and characterized as functions of molecular weight of silicone and crosslinking density. Fourier transform infrared spectroscopy, ¹³C‐NMR, and pyrolysis gas chromatography–mass spectrometry study showed that those copolymers were successfully synthesized. Also, the gel‐permeation chromatography spectrum exhibited a fairly narrow distribution of the molecular weight of the polymer. It was found that the turbidity in ethanol (EtOH) and the glass‐transition temperature of crosslinked VP/VS copolymers are influenced by the amount of crosslinking agent. However, in the case of branched VP/VS copolymers, a transparent solution was obtained, regardless of the molecular weight of silicone. SEM/EDS study revealed that silicone is more abundant on the coating surface than on the interface of coating/glass. This is probably because Si‐containing chains have lower surface energy than that of vinylpyrrolidinone‐containing chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2244–2253, 2002     

Lead(II)‐ion removal by ethylenediaminetetraacetic acid ligand functionalized magnetic chitosan–aluminum oxide–iron oxide nanoadsorbents and microadsorbents: Equilibrium,kinetics, and thermodynamics

Novel nanosized and microsized chitosan–Al₂O₃–Fe₃O₄ (CANF and CAMF, respectively) adsorbents were functionalized with ethylenediaminetetraacetic acid (EDTA) ligands and applied to the removal of Pb(II) ions. The prepared adsorbents were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller analysis, and their adsorption potentials were investigated with Pb(II) as a target metal under various experimental conditions. Our results show that the EDTA functionalization of CANF and CAMF increased their adsorption capacities about 31.5 and 38 times, respectively. The optimum dosage obtained was 1.0 g/L for both EDTA‐functionalized adsorbents, and the maximum adsorption took place at pH = 5.3. The kinetic results revealed that the adsorption obeyed the pseudo‐second‐order model and that the pore diffusion process played a key role in the adsorption kinetics. Also, the results of equilibrium isotherms indicate the good fit of the experimental data by the Langmuir isotherm model under the studied concentration and temperature ranges, and the adsorptions of Pb(II) ions from aqueous solution followed the monolayer coverage of the adsorbents. The maximum Pb(II)‐ion adsorption capacities of EDTA–CANF and EDTA–CAMF were 160 and 157 mg/g, respectively. These metal‐loaded adsorbents could be readily recovered from aqueous solution by magnetic separation and reused. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44360.     

A novel porous nanocomposite of aminated silica MCM‐41 and nylon‐6: Isotherm,kinetic, and thermodynamic studies on adsorption of Cu(II) and Cd(II)

Porous amine‐modified MCM‐41/Nylon‐6 nanocomposite (NH₂‐MCM‐41/NY6 NC) was synthesized by a facile solution casting protocol, which was used as an effective adsorbent for the removal of Cu(II) and Cd(II) from aqueous media. The physicochemical properties of NH₂‐MCM‐41/NY6 NC were studied by scanning and transmission electron microscopies, thermogravimetric analysis, etc. The influence of pH, adsorbent dose, contact time and initial concentration on adsorption performance were investigated in detail. Kinetic and isotherm parameters were evaluated and the data fitted well to the pseudo‐second order and Freundlich isotherm model, respectively. The maximum adsorption capacities of Cu(II) and Cd(II) were about 35.84 and 27.5 mg·g^?1, respectively. The K_d of NH₂‐MCM‐41/NY6 NC for Cu(II) (> ) and Cd(II) (> ) ions uptake in aqueous solution, showed very good values. Thermodynamic parameters suggest that the adsorption is a spontaneous process with an endothermic nature. According to the results obtained, we conclude that this novel porous NH₂‐MCM‐41/NY6 NC could be used for the removal of heavy metal ions from an aqueous solution. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45383.     

Hierarchical self‐assembly of Y‐shaped amphiphilic triblock polyurethane/poly(acrylic acid) complexes: Giant vesicles,vesicles, 3D network,and bulk structures

A simple and effective approach to induce hierarchical self‐assembly of Y‐shaped amphiphilic triblock polyurethane/poly(acrylic acid) complexes system in aqueous media is reported here. Hydrogen bonding interactions and electrostatic repulsive forces, which can be controlled by regulating the pH condition of complexes solution, were the main driving forces to induce morphological transitions. With the gradual decrease of pH value, a variety of micro‐/nanostructures including giant vesicles, small vesicles, multi‐layer three‐dimensional (3D) porous network structures and “bulk” structures were successively obtained. Among these structures, the micron‐scale multi‐layer 3D porous network structure formed from block copolymer/homopolymer complexes was rarely reported. Therefore, this research demonstrates that the hierarchical self‐assembly of polymers complexes in aqueous media is a viable approach to construct different interesting micro‐/nanostructure assemblies, and supplies a new clue for the fabrication of multi‐layer 3D porous network structures. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46503.