Ethylcellulose Solution Research Articles

Fabrication and Characterization of Antimicrobial Ethyl Cellulose Nanofibers Using Electrospinning Techniques.

Ethyl cellulose nanofibers were fabricated by electrospinning techniques using ethyl cellulose solution having concentrations of 150 g/l, using different volume ratios of a binary THF (tetrahydrofuran): DMAc (N,N dimethylacetamide) solvent system. The influence of the composition of the binary solvent system on the surface morphology of ethyl cellulose nanofibers with or without adhered antibiotics was investigated using field emission scanning electron microscope (FE-SEM). To assess the effectiveness of drug release from the nanofibers and their antibacterial activities toward S. aureus, streptomycin was selected as the antibiotic. Disc diffusion and optical density tests were used for the assessment. The antibiotic release from ethyl cellulose fibers was best when the THF to DMAc volume ratio was 3 to 2 (v/v). The optical density test showed the antibacterial effective time of the streptomycin antibiotics loaded in nanofibers was longer than that of the bulk antibiotics against S. aureus bacteria.

Stable dye-sensitized solar cells based on a gel electrolyte with ethyl cellulose as the gelator

A simple gelating process is developed for the conventional acetonitrile-based electrolyte of dye solar cells, based on ethyl cellulose as the gelator. The electrolyte becomes quasi-solid-state upon addition of an ethanolic solution of ethyl cellulose to the conventional acetonitrile-based liquid electrolyte. The photovoltaic conversion efficiency with the new gel electrolyte is only slightly lower than with the liquid electrolyte, e.g., 6.5 % for liquid electrolyte versus 5.9 % for gel electrolyte with 5.8 wt% added ethyl cellulose. Electrolyte gelation has small effect on the ionic diffusion coefficient of iodide, and the devices are remarkably stable for at least 550 h under irradiation at 55 °C.

Formulation and Evaluation of Gastroretentive Floating Beads of Cefuroxime Axetil

Cefuroxime axetil is a second generation antibacterial agent belongs to cephalosporin group. It undergoes rapid metabolism in the intestinal mucosa due to change in pH environment and hence decreased oral bioavailability. A gastro retentive floating beads of cefuroxime axetil were formulated to increase the bioavailability. The floating beads were prepared by Ionotropic gelation method in which drug and calcium carbonate were dispersed in four different concentrations into a polymer mixture of three different combinations such as sodium alginate along with guar gum, sodium alginate with HPMC K4M, and sodium alginate with hydroxy ethyl cellulose solution and then dropping the dispersion into an acidified solution of 3% (w/v) calcium chloride. The prepared beads were evaluated for bead size, entrapment efficiency, in-vitro drug release, swelling study, buoyancy test, SEM, X-ray diffraction, FTIR and in vivo gastric retention time in albino rats. The drug entrapment efficiency was found to be in the range of 54.76 to 81.87%. The in-vitro drug release was observed up to 8 hr. The drug release followed Fickian transport. In vivo studies indicated that a significant increase in gastric residence time of beads.

Relaxation character of the rheological behavior of cellulose ether solutions in a magnetic field

The relaxation character of the rheological behavior of hydroxypropyl cellulose and ethyl cellulose solutions in a magnetic field and without it was studied. Application of magnetic field leads to an increase in the viscosity of cellulose ether solutions. The mechanical and magnetic field energies stored by the solutions at flow were calculated.

Effect of Magnetic Field on Rheological Properties of Cellulose Ether Solutions

Application of a magnetic field is shown to be accompanied by an increase in the viscosity of hydroxyethyl cellulose, ethyl cellulose solutions and sodiumcarboxymethyl cellulose solutions in 2 - 4 times. The concentration dependences of solution viscosity in the presence of a magnetic field are described by curves with maxima.

Low-Temperature Sintering of Nanosilver Paste on a Gold Film Surface

AbstractNanosilver paste with a low sintering temperature is a high-demand interconnection material for electronic devices and components due to its superior electrical, thermal, and thermomechanical properties, as well as the fact that it is lead free. This study presents a nanoscale silver paste that can be sintered at 300 °C using 60-nm silver particles and an ethyl cellulose solution. The rheological and thixotropic behaviors of the typical paste were characterized, and the paste's screen printing ability was analyzed in detail. The paste demonstrates typical shear thinning rheological behavior and thixotropy of pseudoplastic fluids. Thermal characteristics of the 60 nm silver particles were measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to obtain a proper sintering temperature schedule. In this report, we also discussed the solid content, thermodynamic driving force for densification, and sintering process of the nanosilver particles. A 83 wt% of silver solid content at a heating rate of 20 °C/min was favorable for achieving a proper sintering densification.

Surelease or organic solution of ethylcellulose in preparation of sustained release theophylline micromatrices or matrices using spray drying technique

This study evaluated ethylcellulose (EC) in two forms in preparation of sustained release theophylline microparticles using spray drying. Spray dried (SD) samples at different drug:polymer ratios were prepared using Surelease (SDaq) or organic solutions of ethylcellulose (SDor). Properties of particles (yield, particle morphology, size distribution and release profiles) were examined. Differential scanning calorimetry (DSC) and infrared spectroscopy (IR) studies were performed to track polymorphic changes and/or drug polymer interactions. SD samples were compressed and crushing strengths and release profiles were determined. The yields were in the range of 55–70%. The SD samples were nearly spherical with numerous fine particles attached to their surfaces. The SDor samples showed the smallest particle size. No polymorphism or drug–polymer interaction was observed. Uncompressed SDaq samples showed inadequate sustained release of drug compared to SDor samples. Surelease content did not affect drug release from SDaq samples. Tablets prepared from SDaq were softer and showed some plasticity, while those prepared from SDor exhibited higher crushing strengths. Tablets prepared from SDaq showed sustained release properties while the release of drug from compressed SDor samples were too slow. Overall Surelease was unable to sustain release of theophylline from SDaq microparticles, however, in compacted form showed more appropriate drug release than compacted SDor.

Preparation of sustained-release coated particles by novel microencapsulation method using three-fluid nozzle spray drying technique

We prepared sustained-release microcapsules using a three-fluid nozzle (3N) spray drying technique. The 3N has a unique, three-layered concentric structure composed of inner and outer liquid nozzles, and an outermost gas nozzle. Composite particles were prepared by spraying a drug suspension and an ethylcellulose solution via the inner and outer nozzles, respectively, and mixed at the nozzle tip (3N-PostMix). 3N-PostMix particles exhibited a corrugated surface and similar contact angles as ethylcellulose bulk, thus suggesting encapsulation with ethylcellulose, resulting in the achievement of sustained release. To investigate the microencapsulation process via this approach and its usability, methods through which the suspension and solution were sprayed separately via two of the four-fluid nozzle (4N) (4N-PostMix) and a mixture of the suspension and solution was sprayed via 3N (3N-PreMix) were used as references. It was found that 3N can obtain smaller particles than 4N. The results for contact angle and drug release corresponded, thus suggesting that 3N-PostMix particles are more effectively coated by ethylcellulose, and can achieve higher-level controlled release than 4N-PostMix particles, while 3N-PreMix particles are not encapsulated with pure ethylcellulose, leading to rapid release. This study demonstrated that the 3N spray drying technique is useful as a novel microencapsulation method.

Polymer encapsulation of amoxicillin microparticles by SAS process

Encapsulation of amoxicillin (AMC) with ethyl cellulose (EC) by a supercritical antisolvent process (SAS) was investigated. AMC microparticles obtained previously by an SAS process were used as host particles and EC, a biodegradable polymer used for the controlled release of drugs, was chosen as the coating material. In this work, a suspension of AMC microparticles in a solution of ethyl cellulose in dichloromethane (DCM) was sprayed through a nozzle into supercritical CO2. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and HPLC analyses were carried out. The effects of AMC:EC ratio, the initial polymer concentration of the solution, temperature and pressure on the encapsulation process were investigated. Although all the experiments led to powder precipitation, the AMC encapsulation was achieved in only half of the cases, particularly when the lower drug:polymer ratios were assayed. In general, it was observed that the percentages of AMC present in the precipitates were higher on increasing the AMC:EC ratio. In these cases composites rather than encapsulates were obtained. The in vitro release profiles of the resulting materials were evaluated in order to ascertain whether composites can be used as encapsulated systems for drug delivery systems.

Nanofibers obtained by electrospinning of BaTiO3 particles dispersed in polyvinyl alcohol and ethylcellulose

Barium titanate particles (100-300 nm) synthesized by hydrothermal method were dispersed in both polyvinyl alcohol (PVA) and ethylcellulose (EC) solutions. These suspensions were processed by electrospinning. When no particles were added, homogeneous polymeric nanofibers were obtained. Under certain conditions, polymeric suspensions of barium titanate particles were electrospun generating polymeric fibers with BT particles. The effect of a surfactant was also assessed over the formation of nanofibers. The BaTiO3 particles synthesized by hydrothermal method were characterized by X-Ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Fibers were characterized by scanning electron microscopy (SEM).

EFFECTS OF PSEUDOPLASTICITY ON SPREAD AND RECOIL DYNAMICS OF AQUEOUS POLYMERIC SOLUTION DROPLETS ON SOLID SURFACES

The postimpact spreading and recoil behavior of millimeter-size liquid droplets of pure water, water–glycerol solution, and non-Newtonian aqueous solutions of medium-grade hydroxyl ethyl cellulose (HEC 250 MR) on dry horizontal hydrophobic (Teflon) and hydrophilic (glass) substrates is presented. The drop spread–recoil dynamics are captured using a high-speed high-resolution digital video recording and image processing. The non-Newtonian effects of aqueous polymeric solutions on postimpact spreading are contrasted with those for a water–glycerol solution with identical surface tension and zero-shear rate viscosity. For a broad range of drop Weber numbers (20 ≤ We ≤ 200), dynamic visualized records of impact, spreading, and recoil are presented along with their measured temporal variations in dropdiameter-scaled spread and film height. The shear-rate-dependent viscosity of the polymer solution is found to give rise to highly complex spread–recoil dynamics compared to Newtonian liquids. During initial spread, because the shear rate tends to be high, shear-thinning or pseudoplasticity effects manifest in polymer solution drops to alter their spread dynamics. Contrarily, during recoil their higher low-shear apparent viscosity tends to retard recoil and dampen shape oscillations. Shear-rate-dependent non-Newtonian behavior is further seen at low We (low shear rate during spreading), where the maximum spread of HEC solution droplets is comparable to that of high-viscosity water–glycerol solution, whereas at high We (high shear rate during spreading), their maximum spreads are closer to those of low-viscosity water droplets.

Dual rheological responses in Ag pastes

AbstractHighly concentrated suspensions have complex structures that complicate their characterization and study. Highly concentrated suspensions of Ag particles in ethyl cellulose solutions (Ag pastes) were thus studied and dual rheological responses were observed. Under rotational shear, the unpredicted enhancement of shear moduli occurred in the low frequency regime, showing that rheological responses of Ag pastes were strongly influenced by fillers. Under large‐amplitude oscillation, the hydrodynamic‐induced enhancement effect was observed over the whole frequency range, showing that rheological responses of Ag pastes were dominated by the binder solutions. Further studies showed that this dual behavior arose from the dual nature of structures in Ag pastes. The different shear types promoted the development of different structures in rheological experiments. Rotational shear promoted cluster formation, resulting in the unpredicted enhancement; while large‐amplitude oscillation broke the clustering, leading to the hydrodynamic enhancement. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of a magnetic field on the rheological properties of cellulose ether solutions

Application of a magnetic field is shown to be accompanied by an increase in the viscosity of hydroxyethyl cellulose and ethyl cellulose solutions and an additional assembly of macromolecules, as is evident from a gain in the radii of light-scattering particles. The concentration dependences of supramolecular-particle radius and solution viscosity in the presence of a magnetic field are described by curves with maxima.

A Glass Dielectric Paste for Preparation Transparent Spacers of Vacuum Glass by Screen Printing

Vacuum glass is a new building material with excellent energy conservation and sound insulation properties. Usually, the spacers between two pieces of flat glass substrates are mini-rings of metal. In the present research, the spacers were prepared with a glass dielectric paste by screen printing, and then sintered till them transparent. The glass dielectric paste for the preparation of transparent spacers of vacuum glass was prepared by using low melting glass powder and terpineol ethyl cellulose solution. The composition of the paste with preferable properties was evaluated as in mass percent: organic vehicle 20-25, and low melting glass powder 73-80. The rheological behaviors of the typical paste were characterized by using an ARES (RFS-III) rheometer. It is found that a weak flocculated network structure is formed in the paste for the high solid filler. The spacers were prepared by screen printing the paste on the glass substrate and then sintered. The transparent, Vickers hardness of the spacers as well as the binder forces between the spacers and the substrate is reported. The reliability of the prepared transparent spacers for the vacuum glass was discussed.

Development of a Novel and Customizable Two-Solution Mixing Type Spray Nozzle for One-Step Preparation of Nanoparticle-Containing Microparticles

Production of drug nanoparticles is an effective strategy to enhance solubility and oral absorption of water-insoluble drugs. The handling of drug nanoparticles has been an important issue in drug formulation because nanoparticles easily aggregate each other and redispersion of these particles is very difficult. In the present study, we developed a unique two-solution mixing type spray nozzle that can prepare drug nanoparticles in microparticles in one step without any common solvent and surfactant, and then, the prepared formulation were evaluated. Ethylcellulose (EC) and mannitol (MAN) were used as a model polymer of water-insoluble compound and a water-soluble carrier, respectively. We characterized the EC/MAN microparticles produced by the novel spray nozzle when customizing the nozzle parts to mix EC and MAN solution. Relatively smaller EC nanoparticles (<110 nm) in MAN microparticles (approximately 3 µm) were obtained by changing the customizable parts in the nozzle. In addition, the core of EC nanoparticles (<50 nm) was also observed by atomic force microscopy. We also found that the mixing time in the nozzle parts affected the size and the standard deviation of EC nanoparticles. These results suggest that the size of EC nanoparticles in MAN microparticles is controllable by using this unique nozzle. After all, we could prepare MAN microparticles containing EC nanoparticles in one step by using the novel nozzle. The drug/MAN microparticles formulation produced by the nozzle may be useful for the handling of drug nanoparticles.

Ethylcellulose microparticles containing chitosan and gelatin: pH-dependent release caused by complex coacervation

Ethylcellulose microparticles containing chitosan and gelatin were prepared by spray drying water-in-oil (W/O) emulsion. Water phase was chitosan:gelatin solution in distilled water, and oil phase was ethylcellulose solution in dichloromethane. FITC-dextran was included in water phase as a fluorescence dye. The maximum coacervation was observed at pH 6.0 when the ratio of chitosan to gelatin was 1:15. Microparticles containing chitosan and gelatin in the ratio showed a higher release under acidic condition (e.g. pH 4.0) and neutral condition (e.g. pH 7.0), but a lower release at pH 5.0 and pH 6.0. The complex coacervate composed of chitosan and gelatin was efficiently formed at those pHs, and the formation of coacervate would be responsible for the lower release.

Rheological Behavior of Silver Paste Prepared from Nanoparticles

A paste with as low as 300°C sintering temperature was prepared by using nano silver particles and ethyl cellulose solution. The rheological and thixotropic behaviors of the typical paste were characterized and their effects on the screen printing ability were analyzed in details. The paste demonstrates a typical shear thinning rheological behavior and thixotropic of pseudoplastic fluid. The apparent viscosity decreased rapidly with the increase of the shear rate. The paste is proper for the manufacturing electrical components at a low temperature as low as 300°C.

Characterization of ethyl cellulose polymer

Ethyl cellulose (EC) polymer was characterized for its property before considering the interactions with the plasicizer. Ethocel Std.10 FP Premium from Dow chemical company USA was tested for its solubility, morphology and thermal properties. Seven percentage of EC solution in ethanol was found to be the right viscosity used to prepare the film. The EC polymer and EC film without any plasticizers showed almost identical thermal behavior, but in X-ray diffraction showed different arrangements of crystallites and amorphous region. Dynamic mechanical analysis of film showed that without a plasticizer, EC film was not flexible and had very low elongation with high applied force. The aim of the work was to avoid using the commercially available EC dispersions Surelease® and Aquacoat®; both already have additives on it. Instead, Ethocel EC polymer (powder) was characterized in our laboratory in order to find out the properties of polymer before considering the interactions of the polymer with various plasticizers.

A Lead Free Graphite Conducting Paste for Screen Printing

A lead free graphite conducting pastes were prepared by using graphite powder, lead free low-melting glass and terpineol ethyl cellulose solution. By analyzing the sheet resistance, Vickers hardness as well as the adhesion strength of the sintered film prepared by the pastes formulated with different composition, the composition of the paste with preferable properties was evaluated as in mass percent: organic vehicle 60, graphite powder 15~20, and low melting glass 20~25. The films, prepared by the pastes using the lead free glass with a glass transition temperature of 476°C, were perfectly flat and compact after fired at a peak temperature within the range from 520°C to 580°C. The sheet resistance of the fired film with glass content of 25wt% was 135Ω/mm2 when the thickness of the film was 25±3μm, while the Vickers hardness and the binder force between the sintered film and the substrate were favorable. In addition, the rheological behaviors of the typical paste were characterized by using an ARES (RFS-III) rheometer. It is found that a weak flocculated network structure is formed in the paste for the high solid filler.

Temperature and time effects on the structural properties of a non-aqueous ethyl cellulose topical drug delivery system

The structural properties of ethyl cellulose and propylene glycol dicaprylate mixtures were investigated with a view to facilitating use of the system as excepient for topical drug delivery. The working protocol included small-deformation dynamic oscillation in combination with the principle of time–temperature superposition, micro and modulated differential scanning calorimetry, wide-angle X-ray diffraction patterns, infrared spectroscopy, and optical profile analysis in the form of gel particle roughness. In contrast to thermoreversible gelation upon heating of aqueous ethyl cellulose solutions reported widely in the literature, replacing water with propylene glycol dicaprylate and mixing with the polymer yields gels that revert to the solution state with increasing temperature. Time effects were also probed; the continuous increase in viscoelasticity of preparations as a function of time of observation at ambient temperature was accompanied by structural disintegration of the polymeric particles. This was rationalized by proposing that specific polymer–solvent interactions result with aging in particle erosion and the release of polymeric strands that are able to form a three-dimensional structure. It was thus documented that the time–temperature equivalence was active in the system producing a rubbery state in the master curve of viscoelasticity, which extends from ambient to subzero temperatures and should facilitate pharmaceutical applications.