PET-SWNT Nanocomposite Fibers through Melt Spinning

Poly(ethylene terephthalate)-single-walled carbon nanotube (PET-SWNT) nanocomposite fibers have been prepared through melt spinning and drawing. While acting as effective nucleating agents for PET melt crystallization, SWNTs also provide significant reinforcement to PET fibers. For example, the tenacity and initial modulus of the composite fiber with 1 wt% SWNTs were, respectively, 1.8 times and 3.2 times higher as compared to those of the pristine PET fiber prepared under identical conditions. When the draw ratio was increased, tenacity and modulus of the fibers increased, indicating that drawing induced orientation of the polymer molecules and SWNTs. Thermal stability of the fibers was not significantly affected by the presence of SWNTs at low concentrations.     

Incorporation of zeolite and silica nanoparticles into electrospun PVA/collagen nanofibrous scaffolds: The influence on the physical,chemical properties and cell behavior

Cartilage is under extensive investigation in tissue engineering research. Herein, we evaluated scaffolds prepared by composites of polyvinyl alcohol (PVA) and collagen incorporated with zeolite and silica nanoparticles (nZe and nSi). The scaffolds were prepared by the electrospinning method. The mean diameters of nanofibers were 0.61 ± 0.34 µm for PVA/collagen versuss 0.62 ± 0.22 µm and 0.66 ± 0.25 µm for the PVA/collagen/nZe and the PVA/collagen/nSi scaffolds, respectively. DAPI staining results revealed that cell proliferations on the PVA/collagen/nZe and PVA/collagen/nSi were strikingly higher than on the pure PVA/collagen. The results encouraged further investigation of PVA/collagen/nSi scaffolds as biomimetic platform for chondrocyte cells in tissue engineering.     

Characterization and Application of Intercalated Montmorillonite with Verapamil and its Polymethyl Methacrylate Nanocomposite in Drug Delivery

This work examined two drug delivery systems: the first system studied the adsorption of Verapamil hydrochloride drug into montmorillonite clay (MMT) by intercalation process to prepare MMT-Verapamil hybrid at different intercalating time, temperatures, pH values and initial drug concentrations. The second system includes the preparation of MMT-Verapamil hybrid combined with polymethyl methacrylate via an emulsion polymerization process to produce a novel nanocomposite material to be used in drug delivery. The polymerization process was carried out using an ultrasonic technique to achieve a biologically safe drug delivery system. Best conditions for the intercalation of verapamil hydrochloride drug into the interlayer of MMT clay were found to be at 50°C and 1 hr using pH ranges of 4–6. The prepared MMT-Verapamil hybrid and the produced MMT-verapamil-MMA nanocomposite material were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and thermal gravimetric analysis (TGA). The in-vitro release profile of Verapamil in the case of a drug hybrid is faster than the release in the case of a drug nanocomposite in both gastric and intestinal fluids where, in the case of gastric fluid (pH 1.2), about 40% of the loaded drug was released from the drug hybrid in the first 4 h against only 37% in 5 h in the case of drug nanocomposite. Also in the intestinal fluid (pH 7.4), the verapamil release from drug hybrid reached 68% in 5 h against only 57% was released from drug nanocomposites in 7 h.     

In vitro evaluation of electrospun gelatin‐bioactive glass hybrid scaffolds for bone regeneration

Organic–inorganic hybrid materials, composed of phases that interact on a nanoscale and a microstructure that mimics the extracellular matrix, can potentially provide attractive scaffolds for bone regeneration. In the present study, hybrid scaffolds of gelatin and bioactive glass (BG) with a fibrous microstructure were prepared by a combined sol–gel and electrospinning technique and evaluated in vitro. Structural and chemical analyses showed that the fibers consisted of gelatin and BG that were covalently linked by 3‐glycidoxypropyltrimethoxysilane to form a homogeneous phase. Immersion of the gelatin–BG hybrid scaffolds in a simulated body fluid (SBF) at 37°C resulted in the formation of a hydroxyapatite (HA)‐like material on the surface of the fibers within 12 h, showing the bioactivity of the scaffolds. After 5 days in SBF, the surface of the hybrid scaffolds was completely covered with an HA‐like layer. The gelatin–BG hybrid scaffolds had a tensile strength of 4.3 ± 1.2 MPa and an elongation to failure of 168 ± 14%, compared to values of 0.5 ± 0.2 MPa and 63 ± 2% for gelatin scaffolds with a similar microstructure. The hybrid scaffolds supported the proliferation of osteoblastic MC3T3‐E1 cells, alkaline phosphatase activity, and mineralization during in vitro culture, showing their biocompatibility. The results indicate that these gelatin–BG hybrid scaffolds prepared by a combination of sol–gel processing and electrospinning have potential for application in bone regeneration. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Using the Mass Method to Produce PVC/Clay Nanocomposite Foams: The Effect of Nano-clay and Foaming Conditions on Density and Cell size

Nanocomposite foams contain very fine cells because of the fillers in nano scale. Due to the limited size of the cells, the mechanical and physical properties of nanocomposite foams are improved compared to polymer foams. In this study PVC/clay nanocomposite foams containing various concentrations of nano-clay (1, 3 and 5 phr) were successfully prepared. The samples were placed under CO₂ gas pressure at 5 MPa, by immersing in glycerin bath at 60, 70, 80 °C and 20, 30, 40 s, respectively, to form foams. The density and the cell size as a factor of nano-clay content, foaming time and temperature were investigated using Archimedes method and scanning electron microscopy, respectively. The minimum density was obtained in the sample containing 1 phr nanoclay prepared at 80 °C and 40 s. The minimum cell size was related to the sample containing 5 phr nanoclay at 60 °C and 20 s.     

Preparation and characterization of hydrophilicity fibers based on 2-(dimethyamino)ethyl mathacrylate grafted polypropylene by UV- irradiation for removal of Cr(VI) and as(V)

The hydrophilic fibers based on 2-(dimethylamino)ethyl methacrylate (DMAEMA) which could remove Cr(VI) ions rapidly were prepared by UV-irradiation induced grafting of DMAEMA through pre-coating photoinitiator on the fibers and modifying with bromoethane(BE). The FTIR, FESEM, XPS, TG-DTG and contact angle spectra manifested that DMAEMA was grafted onto the surface of PP fibers and subsequently was quaternized. The maximum grafting degree (22.9 %) and exchange capacity of DMAEMA (1.2 mmol g^?1) was obtained when PP fibers was immersed in BP concentration of 0.3 % for 4 h, irradiated with the DMAEMA concentration of 100 % and irradiation time of 20 min, and then was modified with BE. The modified fibers of PP-g-DMAEMA with bromoethane were proved to remove Cr(VI) and As(V) with removal rate of 97.3 % and 96.2 % within 10 min, respectively. The prepared fibers have potential application for the removal of Cr(VI) and As(V) from wastewater highly and rapidly.     

Effects of formaldehyde solution and nanoparticles on mechanical properties and biodegradation of gelatin/nano β-TCP scaffolds

In this study, gelatin/beta tricalcium phosphate (β-TCP) nanocomposite scaffolds were prepared by solvent casting method. The cross-linking method was carried out by adding formaldehyde to gelatin. The microparticles of sodium chloride were used as porogen agent. Characterization of nano β-TCP was performed using XRD, FTIR, and SEM. Results showed that the size of the particles is about 100 nm with spherical morphology. In addition, the scaffold characterization was carried out using FTIR and SEM techniques. Observations showed a porous texture with pore size between 100 and 400 μm. The biodegradability and bioactivity evaluations of the scaffolds were done by immersing them in a simulated body fluid solution for different time periods. The biodegradability studies demonstrated a reduction in the degradation rate of gelatin/β-TCP nanocomposite scaffolds due to the presence of β-TCP nanoparticles. The obtained results of bioactivity tests confirmed the formation of apatite layer on the surface of the scaffolds. Furthermore, the effects of porosity, cross-linking agent, and β-TCP nanoparticles on the bending and compressive properties of the composite scaffolds were examined. According to the mechanical examinations of the scaffolds, the best bending and compressive properties occurred in the presence of 10 and 20 wt% of β-TCP nanoparticles, respectively. The appropriate mechanical properties and biodegradation rate for tissue engineering applications obtained at 1 g of the formaldehyde solution.     

Enzymatic Electrode Obtained by Immobilizing of Urease into a Nanocomposite Film Based on Conducting Polymers and Different Additives

The nanocomposite film was obtained by electrochemical co-polymerization of the corresponding monomers in the presence of functionalized carbon nanotubes and different additives. By immobilizing urease on a modified electrode of type nanocomposite film/platinum substrate a novel amperometric biosensor for the detection of urea was prepared. The polymeric and nanocomposite films were utilized as conducting films for amperometric urea sensing after covalent immobilization of urease onto film-coated electrode. The electrochemical performance of the modified electrode was studied by cyclic voltammetry, chronoamperometry, and scanning electron microscopy. The immobilized urease on the nanocomposite film surface exhibited an excellent electrocatalytic response toward reduction urea. Amperometric response was measured as a function of urea concentration at a fixed potential, in this case the open circuit potential. The obtained sensor showed rapid response and good reversibility. The response time was less than 10 s, while the reversible time was about 5–15 s. The enzymatic nanostructured electrode exhibited high sensitivity, a wide linear range, and low detection limit for electrochemical detection of urea.     

Preparation and Characterization of Functionalized Masterbatch of Montmorillonite and Its Application in Preparing ABS Nanocomposite

The functionalized masterbatch of montmorillonite (FMMT) was prepared when monomer acrylic amide (AM), organic-MMT (OMMT) and initiator dibenzoyl peroxide (BPO) were added to acrylonitrile-butadiene-styrene (ABS) carrier which has been dissolved by 1,2-dichloroethane. The influences of AM and BPO amount, reaction time, and reaction temperature on grafting degree were investigated by the orthogonal experimental design. The range analysis showed that optimal conditions for preparing FMMT are AM (1.6 g), BPO (0.4 g), reaction temperature 90°C and reaction time 2 h. The structure of FMMT was characterized by the test of infrared (IR), x-ray diffraction (XRD) and transmission electron microscope (TEM). The results confirmed that AM was successfully grafted onto ABS, the masterbatch was a kind of intercalculated nanocomposite and the gallery height of nanocomposite was 3.42 nm. When montmorillonite was blended with ABS in the form of masterbatch, ABS/FMMT composite was a kind of exfoliated nanocomposite compared to the ABS/Montmorillonite (MMT), ABS/OMMT composites.     

Electrical and Electromagnetic Interference (EMI) shielding properties of hexagonal boron nitride nanoparticles reinforced polyvinylidene fluoride nanocomposite films

The hexagonal boron nitride nanoparticles (h-BNNPs) reinforced flexible polyvinylidene fluoride (PVDF) nanocomposite films were prepared via a simple and versatile solution casting method. The morphological, thermal and electrical properties of h-BNNPs/PVDF nanocomposite films were elucidated. The electromagnetic interference (EMI) shielding properties of prepared nanocomposite films were investigated in the X-band frequency regime (8–12 GHz). The EMI shielding effectiveness (SE) was increased from 1 dB for the PVDF film to 11.21 dB for the h-BNNPs/PVDF nanocomposite film containing 25 wt% h-BNNPs loading. The results suggest that h-BNNPs/PVDF nanocomposite films can be used as lightweight and low-cost EMI shielding materials.     

Preparation and Performance of High-Barrier Low Density Polyethylene/Organic Montmorillonite Nanocomposite

Montmorillonite (MMT) was first modified with dodecyl dimethylbenzyl ammonium (DDA) salt and octadecyl trimethyl ammonium (OTA) salt. Then low density polyethylene (LDPE)/organic montmorillonite (OMMT) nanocomposites were prepared by twin-screw extruder and hot-press. Transmission electron microscopy (TEM) results showed that OMMT layers were homogeneously intercalated into the LDPE matrix. In terms of MMT, the modification effect of OTA is superior to that of DDA. CO₂ and O₂ barrier properties of nanocomposites were increased by 7 times and 4 times with 0.5 wt.% OTA-MMT loading, respectively. At 2 wt% OTA-MMT loading, water vapor permeability of LDPE has also decreased about 2.5 times. Compared with pure PE film, 49.5% and 178% improvement of tensile strength of nanocomposites films were obtained by addition of only 4 wt.% DDA-MMT and OTA-MMT, respectively. In addition, with only 0.5 wt.% OMMT loading, the onset degradation temperature of nanocomposites increases by 23°C and 26°C for LDPE/DDA-MMT and LDPE/OTA-MMT, respectively.     

Core-shell particles for design of high-performance polymeric materials with good transparency and toughness

The exfoliated graphene oxides (GOs) prepared via the Hummer’s method were well dispersed in water but re-stacked if drying to a powder form as observed by transmission electron microscope and x-ray diffraction pattern. Hence, they were directly mixed with poly(vinyl alchohol) (PVA) in water to fabricate the PVA/GO nanocomposite films by casting the resulting aqueous solutions and drying. As the nanocomposite films with no less than 5 wt% GO content were subjected to combustion, the char residue could preserve their original film profile acting like an inflammable scaffold. The glassy transition temperature of as-fabricated PVA/GO nanocomposite films barely changed with the content of GO but significantly decreased from ~70 to ~10 °C as environmental relative humidity (RH) was increased from 20 to 80 % due to more moisture adsorption. Therefore, the mechanical behavior of PVA/GO nanocomposite films not only depended on the GO content but also RH, exhibiting from rubbery to glassy status.     

改性纳米TiO2固相光催化降解LDPE薄膜的研究

采用苯乙烯接枝改性纳米二氧化钛（TiO2-g-PS）颗粒作为催化剂,制备了一种新型可光催化降解的TiO2-g-PS /LDPE纳米复合薄膜,并在空气中紫外光照下进行了薄膜的固相光催化降解。利用热失重、傅立叶红外光谱和扫描电子显微镜等对光照前后纯LDPE、TiO2/LDPE和TiO2-g-PS /LDPE复合薄膜进行分析表征。结果表明,改性颗粒的催化活性较高,能有效地降解聚乙烯薄膜,复合薄膜经紫外光照336 h后,光降解失重率达到36.2 %。     

Effects of dopant,coagulant, and reinforcing nanofiller on mechanical and electrical properties of wet-spun polyaniline nanocomposite fibers

This paper describes the application of Taguchi experimental design to study the simultaneous effects of the dopant, the coagulant, and multiwalled carbon nanotubes (MWCNTs) used as reinforcing filler on the properties (tensile strength and electrical conductivity) of polyaniline (PANI) nanocomposite fibers produced via a wet spinning process. The MWCNT content was found to be the most significant factor, accounting for 72.8 % of the total contribution of the three selected parameters to the tensile strength. The dopant contributed 17.6 %, while the coagulant had a negligible effect and was therefore pooled. MWCNT content provided the maximum contribution of 98 % to the electrical conductivity, whereas the dopant and the coagulant had negligible effects, with contributions of 0.021 % and 0.247 %, respectively. A scanning electron microscope (SEM) and a tapping-mode atomic force microscope (AFM) were employed to study the morphology of the fibers. The electrochemical and pseudocapacitive properties of the fibers were investigated using cyclic voltammetry (CV). The PANI-AMPSA-MWCNT presented a specific capacitance value of 12.8 F cm^?2. The thermal characteristics of the nanocomposite fibers were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Elemental analysis of the fibers showed a high degree of doping: about 47–55 %.     

Nano-curcumin/graphene platelets loaded on sodium alginate/polyvinyl alcohol fibers as potential wound dressing

Innovative composites of biopolymers and nanomaterials have been exploited to fabricate wound dressings which show functional abilities to improve different stages of wound healing by a variety of mechanisms. In this study, a polymeric nanocomposite dressing is fabricated by electrospinning of a blend of sodium alginate (SA), poly vinyl alcohol (PVA) and graphene nanoplatelets (Gnp). The crosslinking of the nanofibers is done by thermal treatment followed by ionic bonding of the fibers. The crosslinked fibers are loaded by curcumin, a natural potent anti-inflammatory compound, encapsulated in monomethoxy poly ethylene glycol-oleate micelles/polymersomes (NCur). Results indicate that by incorporation of Gnp and NCur into the SA/PVA scaffold the tensile strength is not changed (~7 MPa) but the elongation to break and toughness of the scaffolds significantly increase from 11.25±2.6 and 50.56 to 35.5±5.1% and 125.9 Jm^-3, respectively. The scaffolds support the controlled release of curcumin for 24 h in vitro. Biocompatibility of the scaffolds has been confirmed by cell viability assay on mouse fibroblast cells. Overall, the findings demonstrate the potential applications of the spun fibers for wound dressing purposes.     

Waterborne acrylic–polyaniline nanocomposite as antistatic coating: preparation and characterization

An antistatic and electrically conductive acrylic–polyaniline nanocomposite coating was successfully synthesized by interfacial polymerization of aniline in the presence of acrylic latex. The acrylic latex was prepared through emulsion polymerization, and aniline was polymerized by in situ interfacial polymerization at the interface of acrylic latex/chloroform phase. Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy and CHNS elemental analysis revealed the existence of 6.24 wt% emeraldine salt of polyaniline (PAni) in the dried film of the nanocomposite. Scanning electron microscopy (SEM) confirmed the presence of colloidal polymer particles in the aqueous phase which was confirmed to have some advantages, including prevention of aggregation of particles, dispersibility improvement and enhancement of the PAni nanofibers aspect ratio in the acrylic polymer matrix. According to SEM results, PAni fibers with the length ranging from 12 to 67 µm and diameters between 0.078 and 1 µm, highly dispersed in the acrylic polymer matrix, were successfully synthesized. Thermal, electrical and mechanical properties of the acrylic copolymer were significantly affected by PAni incorporation. The onset degradation temperature in thermogravimetric analysis revealed that the thermal stability of the nanocomposite was improved compared to that of the pure acrylic copolymer. The nanocomposite film showed electrical conductivity of about 0.025 S/cm at room temperature, along with satisfactory mechanical properties, attractive as an antistatic material in coating applications.     

Mn3O4@ZnO Core–Shell Nanocomposite: Synthesis and Characterization

Nano-sized single-phase Mn₃O₄@ZnO core–shell nanocomposite was prepared via a simple one-pot sequential polyol using triethylene glycol as a high boiling point solvent as well as a reducing agent. The presence of both Mn₃O₄ and ZnO was confirmed with X-ray diffractometry. Infrared measurements proved the presence of triethylene glycol on the surface of Mn₃O₄@ZnO core–shell. The average particle size is between 8 and 13 nm. Reference intensity ratios method calculations showed that the weight percentage of phases were found as 54.7 % ZnO and 45.3 % Mn₃O₄. The lower Tc maybe explained by interface effects and dominant ZnO shell in magnetic properties of core–shell nanocomposite.     

Aloe vera incorporated biomimetic nanofibrous scaffold: a regenerative approach for skin tissue engineering

Aloe vera (AV) is one of the medicinal herbs with a well-established spectrum of wound healing, antimicrobial and anti-inflammatory property. AV-mediated therapeutics present significant tissue regenerative activity by modulating the inflammatory and proliferative phases of wound healing. The purpose of the present work was to combine the biological properties of AV and the advantages of electrospun meshes to prepare a potent transdermal biomaterial. The polycaprolactone (PCL) containing 5 and 10 wt % of lyophilized powder of AV was studied for electrospinning into nanoscale fiber mats and compared with PCL/Collagen blend for dermal substitutes. SEM revealed the average diameters of PCL, PCL-AV 5 %, PCL-AV 10 % and PCL/Collagen nanofiber scaffolds in the range of 519 ± 28, 264 ± 46, 215 ± 63 and 249 ± 52 nm, respectively. PCL-AV 10 % nanofiber scaffolds showed finer fiber morphology with improved hydrophilic properties and higher tensile strength of 6.28 MPa with a Young’s modulus of 16.11 MPa desirable for skin tissue engineering. The nanofibers were then used to investigate differences in biological responses in terms of proliferation and cell morphology of mice dermal fibroblasts. It was found that PCL-AV 10 % nanofibrous matrix favored cell proliferation compared to other scaffolds which almost increased linearly by (p ≤ 0.01) 17.79 % and (p ≤ 0.01) 21.28 % compared to PCL on sixth and ninth day. CMFDA dye expression, secretion of collagen and F-actin expression were significantly increased in PCL-AV 10 % scaffolds compared to other nanofibrous scaffolds. The obtained results proved that the PCL-AV 10 % nanofibrous scaffold is a potential biomaterial for skin tissue regeneration.     

Morphology and Properties of Waterborne Polyurethane/CNT Nanocomposite Adhesives with Various Carboxyl Acid Salt Groups

Three series of waterborne polyurethane (WBPU)/carbon nanotube (CNT) nanocomposites were prepared, and their morphology and properties with various 2,2-dimethylol propionic acid (DMPA) and CNT contents were investigated. The CNTs were homogeneously dispersed up to the optimum content in WBPU/CNT nanocomposite films. The degree of homogeneous CNT dispersion increased with increasing DMPA content in WBPU/CNT nanocomposite films. The optimum CNT content showed maximum tensile strength, Young's modulus and adhesive strength of WBPU/CNT nanocomposite film. The optimum CNT contents for WBPU/CNT nanocomposite samples containing 3.61, 5.16 and 5.86 wt% DMPA were about 0.50, 1.00 and 1.50 wt%, respectively. The WBPU/CNT nanocomposite adhesive showed higher adhesive strength at moderately high temperatures (40/60/80/100°C) compared to conventional WBPU. The highest adhesive strength at moderately high temperatures was found with 5.86 wt% DMPA and 1.5 wt% CNT content.     

Production, mechanical properties and in vitro biocompatibility of highly aligned porous poly(ε-caprolactone) (PCL)/hydroxyapatite (HA) scaffolds

We produced highly aligned porous poly(ε-caprolactone) (PCL)/hydroxyapatite (HA) scaffolds by unidirectionally freezing PCL/HA solutions with various HA contents (0, 5, 10 and 20 wt% in relation to the PCL polymer) and evaluated their mechanical properties and in vitro biocompatibility to examine their potential applications in bone tissue engineering. All the prepared scaffolds had a highly aligned porous structure, in which the HA particles were uniformly dispersed in the PCL walls. The elastic modulus of the PCL/HA scaffolds significantly increased from 0.12 ± 0.02 to 2.65 ± 0.05 MPa with increasing initial HA content from 0 to 20 wt%, whereas the pore size decreased from 9.2 ± 0.7 to 4.2 ± 0.8 μm. In addition, the PCL/HA scaffolds showed considerably enhanced in vitro cellular responses that were assessed in terms of cell attachment, proliferation and osteoblastic differentiation.