Concentration Of Coating Solution Research Articles

Effects of coating solution concentration on the interlaminar shear strength of carbon fiber/epoxy/nano-CaCO3 composites

Abstract Previously, we have shown that the effects of the coating solution concentration of coupling agent on the interlaminar shear strength of fiber/epoxy composites were best investigated with 4 wt.% nano-CaCO3 content. Here, five different types of composites were prepared: (E–0–4): composites modified by untreated nano-CaCO3, (E–1.1–4): composites modified by nano-CaCO3 with 1.1 wt.% coating solution concentration treatment. Similarly, samples E–2.3–4, E–3.5–4 and E–4.6–4 were also fabricated. The results show that nanocomposites prepared with 2.3 wt.% and 3.5 wt.% coating solution concentration treatment have the best shear properties, including interlaminar shear strength, elongation at break and fracture work. With 2.3 wt.% coating solution concentration treatment, these have values of 142.4 MPa, 1.95 mm and 1.86 J, which can increase 11%, 41% and 39% compared to the composite prepared with untreated nano-CaCO3, respectively.

Pervaporation separation of dimethyl carbonate/methanol binary mixtures with poly(vinyl alcohol)-perfluorslulfonic acid/poly(acrylonitrile) hollow fiber composite membranes

Using poly(vinyl alcohol) (PVA) and perfluorslulfonic acid (PFSA) as coating materials, poly(acrylonitrile) (PAN) hollow fiber ultrafiltration membrane as substrate, PVA-PFSA/PAN composite membranes were fabricated by dip-coating method. The fabricated composite membranes were used to the separation of dimethyl carbonate (DMC)/methanol (MeOH) binary mixtures by pervaporation process. SEM images verify that the coated layer is well combined with substrate and the thickness nearly linearly increases with the coating solution concentration. The separation factor increases but at cost of the decline of permeation flux when the concentration of the coating solution or its PVA mass fraction increase. The permeation flux increases and separation factor slightly increases with the feed temperature increasing at 30–60 °C. The increase of feed MeOH concentration leads to an improvement of permeation flux and a decline of separation factor.

Effect of coating method on gas separation by PDMS/PES membrane

AbstractIn this study, polydimethylsiloxane (PDMS)‐coated polyethersulfone (PES) composite membrane was prepared for gas separation. “Film casting” and “dip‐coating” techniques were used for producing selective PDMS layer on the surface of the PES support. The effects of coating technique and conditions including coating solution concentration and curing temperature on permselectivity of CO2, CH4, and N2 were investigated. The prepared PES support did not provide any selectivity to the gases. When the concentration of PDMS coating solution was increased, initially permeability of CO2 was rapidly dropped and then gradually reached to an almost constant value. The optimum concentration of coating solution was 5 wt%. Curing temperature showed no pronounced effect on the CO2 permeability and selectivity. In “film casting” method, double coating showed superior permeability and selectivity. However, triple “dip‐coating” was promising. The selectivity of composite membrane prepared by “dip‐coating” was higher than “film casting” method. CO2/N2 and CO2/CH4 selectivity of five sequential dip‐coated composite membranes was 45.5 and 9.3, respectively. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers

Design and Optimization of Polyphosphazene Functionalized Fiber Matrices for Soft Tissue Regeneration

Electrospun polycaprolactone nanofiber matrices surface functionalized with poly[(ethyl alanato), (p-methyl phenoxy),] phosphazene were fabricated for the purpose of soft skeletal tissue regeneration. This preliminary study reports the effect of fiber diameter and polyphosphazene surface functionalization on significant scaffold properties such as morphology, surface hydrophilicity, porosity, tensile properties, human mesenchymal stem cell adhesion and proliferation. Six fiber matrices comprised of average fiber diameters in the range of 400-500, 900-1000, 1400-1500, 1900-2000, 2900-3000 and 3900-4000 nm were considered for primary evaluation. After achieving the greatest proliferation while maintaining moderate tensile modulus, matrices in the diameter range of 2900-3000 nm were selected to examine the effect of coating with 1%, 2% and 3% (weight/volume) polyphosphazene solutions. Polyphosphazene functionalization resulted in rougher surfaces that correlated with coating solution concentration. Analytical techniques such as energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, elemental analysis, differential scanning calorimetry, water contact angle goniometry and confocal microscopy confirmed the presence of polyphosphazene and its distribution on the functionalized fiber matrices. Functionalization achieved through 2% polymer solutions did not affect average pore diameter, tensile modulus, suture retention strength or cell proliferation compared to PCL controls. Surface polyphosphazene functionalization significantly improved the matrix hydrophilicity evidenced through decreased water contact angle of PCL matrices from 130 degrees to 97 degrees. Further, enhanced total protein synthesis by cells during in vitro culture was seen on 2% PPHOS functionalized matrices over controls. Improving PCL matrix hydrophilicity via proposed surface functionalization may be an efficient method to improve cell-PCL matrix interactions.

Studies on the coating layer in a PTFPMS/PEI composite membrane for gaseous separation

Composite membranes have been prepared by coating a thin layer of polyfluoropropylmethylsiloxane (PTFPMS) on the dense layer of asymmetric polyetherimide (PEI) membranes to plug the defects. The effects of PTFPMS molecular weight and coating solution concentration on the separation performance of the composite membranes have been investigated theoretically and experimentally. The results reveal that PTFPMS 20K (number average molecular weight of 20K) has smaller molecular size than the defect diameter of the PEI membrane and can plug the defects when its concentration is higher than 5wt%. With the increase of PTFPMS 20K concentration in the coating solution, the gas permeance of the composite membrane decreases while the separation factor increases. The PEI composite membrane prepared with 20wt% of PTFPMS 20K exhibits the H2 permeance of 11.8GPU (1GPU=10−6cm3/(cm2scmHg)), combining with the O2/N2 and H2/N2 separation factors of 6.9 and 107.3, respectively. On the other hand, PTFPMS 1100K (number average molecular weight of 1100K) can hardly penetrate into the defects of PEI composite membrane regardless of its concentration in coating solution because of the larger molecular size of PTFPMS 1100K over the diameter of the defect. Accordingly, the PEI composite membrane prepared with the PTFPMS 1100K as coating layer shows poor separation performance. Therefore, appropriate match of size between coating material and defect is critical to obtain high separation performance for the PEI composite membrane. More importantly, the solvent resistance experiments indicate that the PTFPMS/PEI composite membrane can maintain its stable separation performance after immersed in heptane and petroleum ether.

Silk fibroin encapsulated powder reservoirs for sustained release of adenosine

Due to its unique properties, silk fibroin was studied as a biodegradable polymer vehicle for sustained, local delivery of the anticonvulsant adenosine from encapsulated reservoirs. Silk is a biologically derived protein polymer that is biocompatible, mechanically strong and degrades to non-toxic products in vivo. To achieve local, sustained, controlled adenosine release from fully degradable implants, solid adenosine powder reservoirs were coated with silk fibroin. Material properties of the silk coating including thickness, crystallinity and morphology were investigated to assess the relationships between silk coating biomaterial features and adenosine release from silk encapsulated reservoirs. Reservoir coating thickness was varied through manipulation of the silk coating solution concentration and number of coatings applied. Release studies were also performed in proteinase type XIV to model the effects of degradation. Increasing the barrier to diffusion, either by increasing coating thickness or crystallinity was found to delay adenosine burst, decrease average daily release rate, and increase duration of release. In the case of encapsulated reservoirs coated with eight layers of 8% (w/v) silk, a linear release profile was observed and adenosine release was sustained for 14 days. The ability to achieve nearly constant release for 2 weeks for adenosine via control of the silk coating suggests these encapsulated reservoirs represent a novel system for delivering adenosine. We anticipate that this approach could also be extended to other implant needs and small-molecule drugs to treat a range of clinical needs.

Preparation of PFSA/PSf hollow fiber composite membranes with recovered PFSA for the pervaporation separation of EtOH/H2O

Perfluorosulfonic acid/Polysulfone(PFSA/PSf) hollow fiber composite membranes have been prepared by dip-coating method using PSf ultrafiltration (UF) membrane as substrate with recovered PFSA. The composite membranes were applied to the pervaporation separation of 95% ethanol (EtOH)/H2O mixture. SEM images show that the thickness of the PFSA skin layer of the composite membranes is about 2 μm, much thinner than those of other PFSA composite membranes revealed in the literatures. Effects of annealing temperature, coating solution concentration and counter-ions of PFSA on the pervaporation performances of the composite membranes were investigated. The total flux decreases and separation factor increases with the increase of annealing temperature. The highest permeation flux of 3230 g m−2 h−1 and a separation factor of 5.4 is obtained for the composite membrane annealed at 80°C. The lowest permeation flux of 396 g m−2 h−1 and a separation factor of 27.7 is obtained for the composite membrane annealed at 160°C. The permeation performances of the PFSA/PSf composite membrane are evidently influenced by the counter-ions of PFSA. The flux sequence of the PFSA/PSf composite membranes with different counter-ions is H+>Li+>Ca2+>Mg2+>Na+>K+>Ba2+>Fe3+>Al3+, and the separation factor sequence is H+ Na+>K+. There are very little variations of ΔEapp values between the composite membranes with three divalent counter-ions (Mg2+, Ca2+ and Ba2+), and the ΔEapp values of the composite membranes with two trivalent counter-ions (Fe3+ and Al3+) are relatively high.

Preparation of hollow fiber poly(N,N-dimethylaminoethyl methacrylate)–poly(ethylene glycol methyl ether methyl acrylate)/polysulfone composite membranes for CO 2/N 2 separation

A hollow fiber composite membrane was prepared by coating a poly(N,N-dimethylaminoethyl methacrylate)–poly(ethylene glycol methyl ether methyl acrylate) (PDMAEMA–PEGMEMA) skin layer onto a porous polysulfone (PSf) substrate. The influence of fabrication parameters including coating solution concentration and coating times on the permselectivity of the prepared membrane was investigated. For the composite membrane prepared from the optimal fabrication parameter, its CO 2 permeance was about 30 GPU with CO 2/N 2 selectivity of 31 at 35 °C and 202.65 kPa. Moreover, the effects of experimental temperature and pressure on the permselectivity of hollow fiber composite membranes were evaluated. The gas permeance increased with the increase of temperature, which obeyed Arrhenius relation. With the increase of pressure, N 2 showed the similar permeance that meant the transport of N 2 through membrane followed solution–diffusion mechanism, while for CO 2, its permeance underwent a two step change (first increased then decreased) which suggested there might be two transporting models for CO 2 (solution–diffusion and facilitated transport). In addition, it was found that water vapor in the feed gas not only caused plasticization, but also enhanced the interaction of CO 2 with amino groups in PDMAEMA–PEGMEMA skin layer. Both of the two effects contributed to a higher CO 2 permeance compared with the condition that water vapor was absent.

PEMBUATAN DAN MIKROENKAPSULASI EKSTRAK ETANOL BIJI JINTEN HITAM PAHIT (NIGELLA SATIVA LINN.)

The aim of this study is to convert Nigella sativa black seed extract from liquid phase into solid phase by microencapsulation using spray drying method. The benefits hoped from this research are obtaining the dry extract to be formulated into pharmaceutical variable dosage forms in order to increase the usefulness and variability products ofNigella sativa black seed extract. The spray drying method was done by adding Nigella sativa black extract into the gum arabic and maltodextrin solution. The evaluation of microencapsulated extract is including drug content, encapsulation efficiency, flowproperties, compressibility, angle of repose, moisture content, particel size distribu-tion and microstructure of microcapsules. The result showed that microencapsula-tion of Nigella sativa black seed extract can be produced by spray drying method. The highest microencapsulation efficiency is at the coating solution concentration of 20% (gum arabic : maltodextrin = 50 : 50) and Nigella sativa black extract percentage of 30%.

Gas permeation in amine functionalized silicon rubber membranes

Silicon rubber (SR) based thin film composite (TFC) membranes find increasing applicability in various industrial separations owing to its excellent thermal and chemical stability. The functionalization of SR would provide enhanced separation characteristics for certain separation applications. The present research focuses on gas permeation properties of dense and thin film composite membranes based on amine substituted silicon rubber (ASR) and unsubstituted silicon rubber (SR). The dense membrane sorption analysis indicated that presence of amine functionality in ASR increased pressure dependant CO 2 sorption capacity. Owing to this, an elevation of CO 2 permeability by 15% and CO 2 based selectivities by 22–34% in comparison to that of unsubstituted SR was observed. The TFC membranes with SR and ASR as the selective layer on the top of different ultrafiltration (UF) supports with varying properties based on polyacrylonitrile and polysulfone were prepared. The effects of crucial parameters that affected TFC membrane performance, viz., coating solution concentration, UF support membrane porosity and nature of materials were investigated. The preparation of ASR based TFC membranes was demonstrated with a simple crosslinking agent—glutaraldehyde while analyzing effects of crosslinking time on their permeation properties. Polyacrylonitrile (PAN) was found to be better support layer material for ASR based TFC formation than polysulfone (PSF). Thin defect free coating layer can be obtained by appropriate combination of coating solution concentration and support UF membrane porosity. The analysis of effective skin layer thickness of TFC membranes indicated that careful optimization of these parameters is necessary to achieve defect free TFC membranes possessing a good combination of permeance and selectivity.

Effects of surface coating on the controlled release of vitamin B 1 from mesoporous silica tablets

The controlled release of vitamin B 1 (VB 1, thiamine hydrochloride) from mesoporous silica tablets coated with a series of sol–gel coatings was investigated. Tetraethoxysilane (TEOS), n-propyltriethoxysilane (PTES), n-octyltriethoxysilane (OTES), bis(trimethoxysilyl)hexane (TSH), bis(triethoxysilyl)octane (TSO), bis (trimethoxysilylpropyl)amine (TSPA), and bis[(3-trimethoxysilyl)propyl]ethylenediamine (TSPED) were used as precursors for the coatings. The effects of organosilane type and concentration, the number of coatings, drying temperature, and release media on VB 1 release from the coated mesoporous silica tablets were comprehensively examined. The TSH, TSO, TSPA, and TSPED coatings were found to be more effective in suppression of release than the other coatings. VB 1 release decreases with the increase in the number of coatings and drying temperature. It was found that there is an optimal coating solution concentration for the controlled release. In general, more VB 1 is released in 0.01 M HCl solution than in 0.05 M phosphate buffer solution at pH 7.4 because of the electrostatic repulsions between the protonated VB 1 cations and the positively charged mesoporous silica carrier/coatings. The experimental results show that drug release can be easily controlled by changing the organosilane type and the number of coating. The method used in this study is an effective and flexible way for controlled release due to the high drug loading and the easy control of release rate.

Morphology control of highly-transparent indium tin oxide thin films prepared by a chlorine-reduced metallo-organic decomposition technique

Indium tin oxide thin films were prepared by a chemical solution deposition route based on a one pot reaction of indium acetate, tin tetrachloride pentahydrate and propionic acid. The films were heat-treated in oxidising atmosphere and post-annealed in forming gas containing 10% hydrogen. It was found that the coating solution concentration exerted a major influence on the morphology of the films. Low-concentrated solutions yielded layers with columnar structure while higher molarities led to fine-grained granular films. Under optimised conditions, thin films of indium tin oxide exhibiting a resistivity of 1 · 10 − 3 Ω cm were obtained. The transparency was determined to a high level of above 90% in the entire visible range of the spectrum.

Preparation and properties of metal-PVA composite hydrophilic ultrafiltration membranes

Metal-polyvinyl alcohol (PVA) composite ultrafiltration membranes were prepared by coating a certain concentration of PVA solution on metallic fiber sintered membranes. The effects of preparation conditions, such as the coating solution concentration, sequence and times of coating, and heat-treatment on the properties of the composite membranes were studied. The results show that the hole diameter of the composite membrane decreases with the increases of the concentration of PVA, the hole diameter of composite membrane is different when the sequence of coating is different. When the higher concentration of PVA solution is used to coat the metallic membrane for the first time and the other smaller one for the second time, the hole diameter of the composite membrane is relatively small, compared with that of the composite membrane made by the smaller concentration of PVA solution for the first time and the other higher one for the second time. The holes of the composite membrane contract and the stability of the membrane is improved by heat treatment. When metal-PVA composite hydrophilic membranes are used to treat the oil/water emulsion with the concentration of 1000 mg·L−1, the retention is from 80% to 90%, and the permeate flux is from 15 L·m−2·h−1 to 40 L·m−2·h−1 at pressure of 0.2 to 0.3 MPa.

Preparation of CuxS-Coated ZnS:Ag, Cl Phosphor Film with In2O3 Coprecipitation

In this study, the CuxS conductive layer is coated on the particle surface of ZnS:Ag, Cl by a wet chemical reaction and using Cu(CH3COO)2·H2O as the coating source. The low-voltage phosphor film is prepared with In2O3 coprecipitation. From the analyses of X-ray diffraction (XRD) patterns, a preferential orientation phenomenon of the phosphor film is observed. Electron probe microanalysis (EPMA) reveals that Cu ions in the CuxS-coated ZnS:Ag, Cl are homogeneously distributed. After 4 h of coating at room temperature, the Cu and O concentrations in the CuxS-coated ZnS:Ag, Cl phosphor are 2.41 and 0.125 mol%, respectively. The luminance of the phosphor increases with coating time and coating solution concentration. However, the luminance of phosphor film is degraded due to the oxidized phosphor surface. In2O3 coprecipitated with the prepared phosphor film enhances the luminance and stabilizes the luminance efficiency of the phosphor.

Macroflux microprojection array patch technology: a new and efficient approach for intracutaneous immunization.

We evaluated the Macroflux microprojection array patch technology as a novel system for intracutaneous delivery of protein antigens. Macroflux microprojection array systems (330-microm micro-projection length, 190 microprojections/cm2, 1- and 2-cm2 area) were coated with a model protein antigen, ovalbumin (OVA), to produce a dry-film coating. After system application, microprojection penetration depth, OVA delivery, and comparative immune responses were evaluated in a hairless guinea pig model. Macroflux microprojections penetrated into hairless guinea pig skin at an average depth of 100 microm with no projections deeper than 300 microm. Doses of I to 80 microg of OVA were delivered via 1- or 2-cm2 systems by varying the coating solution concentration and wearing time. Delivery rates were as high as 20 microg in 5 s. In a prime and boost dose immune response study, OVA-coated Macroflux was most comparable to equivalent doses injected intradermally. Higher antibody titers were observed when OVA was administered with the microprojection array or intradermally at low doses (1 and 5 microg). Macroflux administration at 1- and 5-microg doses gave immune responses up to 50-fold greater than that observed after the same subcutaneous or intramuscular dose. Dry coating an adjuvant, glucosaminyl muramyl dipeptide, with OVA on the Macroflux resulted in augmented antibody responses. Macroflux skin patch technology provides rapid and reproducible intracutaneous administration of dry-coated antigen. The depth of skin penetration targets skin immune cells; the quantity of antigen delivered can be controlled by formulation, patch wearing time, and system size. This novel needle-free patch technology may ultimately have broad applications for a wide variety of therapeutic vaccines to improve efficacy and convenience of use.

Resistance to nonspecific protein adsorption by poly(vinyl alcohol) thin films adsorbed to a poly(styrene) support matrix studied using surface plasmon resonance.

Thin films of poly(vinyl alcohol) (PVA) polymer were prepared on a flat, nonporous, poly(styrene) support matrix by adsorption from aqueous solution and were characterized in order to investigate the nonspecific adsorption of proteins to a chromatographically relevant surface. The integrity and surface coverage of the PVA thin films were established by surface analysis and atomic force microscopy imaging. The adsorption of the PVA polymers to the poly(styrene) substrate and the nonspecific adsorption of proteins to the PVA-coated surface were monitored using surface plasmon resonance. PVA was strongly bound to the poly(styrene) surface, but the surface density of the adsorbed PVA polymers was affected substantially by the concentration, molecular weight, and degree of hydrolysis of PVA polymers used. There was evidence of increasing degrees of unfolding of the PVA polymer onto the poly(styrene) surface as the concentration of the the PVA coating solution increased. Complete PVA coverage of the poly(styrene) surface was observed at PVA concentrations of 0.1 mg/mL or greater but with significant influence of both molecular weight and degree of hydrolysis of the PVA polymers. Resistance of the PVA-coated poly(styrene) surface to the nonspecific adsorption of human serum albumin (HSA) correlated with the degree of surface coverage of the PVA. The use of anti-HSA as a probe for adsorbed HSA suggested that HSA was displacing PVA from the poly(styrene) surface at the lower PVA surface coverage. A complete barrier to nonspecific protein adsorption was observed with a PVA coating solution concentration of greater than 0.1 mg/ mL with a degree of hydrolysis of <88%.

Blue CuxS coated ZnS:Ag,Cl phosphor as potential field emission display material

The ZnS:Ag,Cl phosphor shows a blue luminescence due to electron–hole recombination at donor–acceptor pairs. Ag dopant acts as the acceptor and Cl co-dopant acts as the donor. For conductivity treatment, the CuxS conductive layer is coated on the particle’s surface of ZnS:Ag,Cl by a wet chemical reaction. The low voltage phosphor film is prepared by sedimentation. Analyses by x-ray diffraction patterns and scanning electron microscopy photographs observe a preferential orientation phenomenon of the phosphor film. Electron probe microanalysis reveals that the Cu ions in the CuxS coated ZnS:Ag,Cl are homogeneously distributed. For CuxS coated at room temperature, the luminance intensity of the phosphor film is increased with the coating time and coating solution concentration. However, the luminance of phosphor film will degrade due to the oxidized phosphor’s surface. A proper heat treatment enhances the luminance of the phosphor film. A high luminance is observed from the CuxS coated ZnS:Ag,Cl phosphor and it is compatible for field emission display applications.

Preparation of composite membranes by a spin coating process

The formation of composite membranes on a laboratory scale by spin coating a selective layer of poly (4-methyl-1-pentene) (PMP) onto a microporous polysulfone support is described. In most cases the support had been precoated with an intermediate layer of poly (dimethyl siloxane) (PDMS). The thickness of the PMP layer, determined indirectly from gas flux measurements on the composite membrane, can be controlled within certain limits by varying the spinning speed, the coating solution concentration or the number of selective layers coated onto the substrate. Coated skin thickness varies approximately with the inverse of the square root of spin speed and with the second power of the coating solution concentration. The model coefficients compare well with those of models proposed for the production of photoresists in which polymer films are spin coated onto non-porous substrates. Gas permeation characteristics of the composite membranes were adequately described by a series resistance model. Composite membranes made without a PDMS intermediate layer required more than one layer of the selective polymer to bridge the larger pores and ensure a defect-free skin. For thin selective layers, these membranes have selectivities somewhat higher thanthat of PMP, since the PSF matrix of the substrate participates in the separation. Thus, multilayer composite membranes formed directly on microporous PSF substrates can be superior to composites with a PDMS intermediate layer.