Co-diffusion Method Research Articles

Nano-microcapsules loaded with nano-antibacterial agents for long-term inhibition of drug-resistant strains

There are growing concerns and worries about the safety of public facilities and equipment. Therefore, coating products with antibacterial properties have become the key to solve this problem, and there is an urgent need to develop new antibacterial architectural coatings. In this study, polystyrene nano-microspheres (PS NMS) were prepared from styrene as raw material. PS nano-microcapsules (PS NMC) were prepared by solute co-diffusion method (SCM) using PS NMS as a template, which were modified to obtain PS-OH NMC. CuS nanoparticles (CuS NPs) with antibacterial activity were further loaded to prepare CuS@PS-OH NMC with long-term antibacterial activity. The SEM results showed that the particle size of CuS@PS-OH NMC was about 410 nm, which was larger than that of PS-OH NMC. The characterization of UV and IR spectra confirmed that CuS NPs were not only encapsulated into PS NMC in large quantities, but also adhered to its surface in a small amount. CuS@PS-OH NMC has good water solubility and can slowly release Cu2+, showing good long-term antibacterial properties against Methicillin-resistant Staphylococcus aureus (MRSA). The CuS@PS-OH NMC developed in this study has excellent performance, good antibacterial effect, environmental friendliness, low price, etc. More importantly, it can efficiently and long-term inhibit MRSA, and can be used as a potential antibacterial architectural coating for special scenarios such as hospitals, schools and densely populated places, which has excellent social and economic value.

High efficiency n-PERT solar cells by B/P co-diffusion method

In this work, boron paste was coated on the silicon surface by spin-coating method, and the boron-doped emitter and phosphorus-doped back surface field were fabricated in one co-diffusion process, because the boron paste acted as a barrier during phosphorus diffusion. Then, n-PERT (Passivated Emitter Rear Totally-diffused cell) solar cells were successfully prepared by this B/P co-diffusion method with the front efficiency of 20.41% and the back efficiency reaching 18.32%. It was demonstrated that the emitter and back surface field formed a good passivation layer on top by thermal oxidation respectively, which enabled open-circuit voltage to reach 648.7 mV. It should be emphasized that the whole process was effectively simplified compared with the conventional process of n-PERT solar cells. Thus, these first results indicate that B/P co-diffusion might be a promising alternative method for mass production of the n-PERT solar cells.g

A temporal disc co-diffusion method detects piperacillin-tazobactam resistance in Serratia marcescens isolates reportedly susceptible by conventional methods

Laboratory interpretation of susceptibility data concerning the AmpC-producing Enterobacteriaceae is confusing to clinicians. Typical organisms included in this category are Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii, Morganella morganii, and Serratia marcescens. These organisms frequently appear susceptible to extended spectrum cephalosporins by standard in vitro testing, although this is highly contested by treatment failures in cases of invasive infections. The mechanisms of resistance were postulated to be ampC induction or de-repression during therapy. As an alternative to carbapenems, piperacillin-tazobactam has been commonly used for its apparent activities against AmpC producers. In this laboratory study, when cefoxitin was used as an ampC-inducing agent in vitro, piperacillin-tazobactam showed activity in only a limited number of AmpC producers. Most notably, a temporal disc co-diffusion method detected inducible piperacillin- tazobactam resistance in all 20 strains of S. marcescens tested. With more standardized measurement, this method improves our previous Kirby-Bauer disc approximation method for the detection of ampC-mediated inducible resistance.

Influence of SMA content on the electro-optical properties of polymer-dispersed liquid crystal prepared by monodisperse poly(MMA-co-SMA)/LC microcapsules

Monodisperse poly(methyl methacrylate) (PMMA) particles containing various concentrations of stearyl methacrylate (SMA) were prepared, and a liquid crystal (LC) was swollen into the particles using a solute co-diffusion method (SCM). Phase separation behaviors between the polymer and LC were monitored by utilizing an optical and a polarized microscope (OM/POM). The monodisperse LC microcapsules were then applied to a polymer-dispersed liquid crystal (PDLC), and the electro-optical properties were investigated. As a result, the threshold and driving voltages were improved when the SMA content increased. The long alkyl chains of SMA in the capsules should exist at the interface of the LC and polymer resulting in an enhancement of phase separation between the polymer and LC, which largely influences the electro-optical properties of PDLC.

Electro-optical properties of polymer-dispersed liquid crystal prepared by monodisperse poly(methyl methacrylate)/fluorinated liquid crystal microcapsules

A liquid crystal (LC) containing the fluorine group was encapsulated into poly(methyl methacrylate) (PMMA) particles by using the solute co-diffusion method (SCM). The PMMA/LC composites were applied to a polymer-dispersed liquid crystal (PDLC) and their electro-optical properties were investigated. The medium solvency, methylene chloride (MC) content, and the crosslinking density of substrate particles were adjusted for the complete swelling of LC into the substrate particles during the SCM procedure. In comparison with the PDLC film prepared by conventional PIPS method, the PDLC by microcapsules showed a good electro-optical property due to uniform and mononuclear type of LC domains. In addition, the size of LC droplets in the particles increased with increasing the LC content, resulting in the enhancement of electro-optical property. The hysteresis effect of PDLC using LC microcapsules was negligible.

The influence of nematic liquid crystal content on the electro-optical properties of a polymer dispersed liquid crystal prepared with monodisperse liquid crystal microcapsules

Highly monodisperse poly(methylmethacrylate) (PMMA)/liquid crystal (LC) microcapsules were prepared by the solute codiffusion method (SCM). In SCM, the solvency of the dispersion medium and the swelling temperature were controlled to ensure complete swelling of the LC into the PMMA substrate particles. After the solvent evaporation procedure, mononuclear LC domains were formed in every particle, and overall the LC microcapsules maintained a spherical shape, monodispersity and smooth surface. PDLC cells prepared using the LC microcapsules exhibited an excellent contrast ratio and transmittance. By increasing the LC content in these LC microcapsules, the electro-optical properties of PDLC cells have been greatly improved.

Novel Light Emitting Diode Using Organic Electroluminescence Microcapsules

AbstractNovel light emitting diodes (LEDs) were prepared using electroluminescence (EL) material/polymer microcapsules (ELC). N‐vinylcarbazole as a hole‐transporting component and methyl methacrylate (MMA) were copolymerized for producing the seed particles using dispersion polymerization. An oxadiazole derivative, synthesized as a electron‐transporting component, and tris(8‐hydroxyquinolinato) aluminium(III) (Alq3) were incorporated into the polymer particles by using the solute co‐diffusion method (SCM). The LEDs for the EL characterization were fabricated in a thin sandwich configuration: Al anode/ELC/ITO cathode. The surface imaging of the LED prepared using ELC was performed by atomic force microscopy (AFM). The EL characteristics of the ELC were investigated by UV, photoelectron and luminescence spectroscopy, and the current‐voltage and the light‐voltage characteristics for the LED were determined.Encapsulation procedure using solute co‐diffusion method (SCM).magnified imageEncapsulation procedure using solute co‐diffusion method (SCM).

Photochromic characteristics of monodisperse microcapsules containing azobenzene derivative-doped nematic liquid crystals

Highly mono-sized dye-doped liquid crystal (LC) microcapsules were prepared by the solute codiffusion method for application in photoswitchable devices. Azobenzene derivatives, which can be photoisomerized by irradiation with UV (366 nm) and visible (433 nm) light, were used as a photoresponsive dichroic dye. The microcapsules have a spherical shape and a single dye-doped LC domain. After UV light (366 nm) irradiation, PDLC films prepared using the microcapsules attained a photostationary state within 10 min and this state maintained stability. PDLC films made by employing a dichroic dye having electron donor and acceptor groups in the molecule showed especially good photoisomerization properties. The reversible trans-cis -photoisomerization occurred sharply by irradiating alternately with visible and UV light.

Phase separation behavior of encapsulated liquid crystals in monodispersed acetalized poly(methylmethacrylate) particles

To improve the degree of phase separation between polymer and LC in LC microcapsules, poly(methylmethacrylate-co-vinylacetate) substrate particles were acetalized by using aldehydes having a different chain length. LC microcapsules were prepared by the solute co-diffusion method (SCM). The phase separation behavior was evaluated with a differential scanning calorimeter (DSC). The degree of phase separation between LC and substrate particles modified with butyl aldehyde was relatively high in comparison with those modified with hexanal and octanal. This means that poly(vinylbutyral) (PVB) moiety in substrate particles causes the complete phase separation and a single LC domain formation. On the contrary, as the aldehyde chain lengthened, the phase separation of LC domain was inhibited.

The effect of mono-sized liquid crystal domains on electro-optical properties in a polymer dispersed liquid crystal prepared by using monodisperse poly(methylmethacrylate)/liquid crystal microcapsules

Highly mono-sized poly(methyl methacrylate) (PMMA)/liquid crystal (LC) microcapsules having a mono-sized single LC domain were prepared by the solute codiffusion method and solvent evaporation. The size of the LC domain in the microcapsules could be controlled by the amount of LC introduced during the swelling stage. The electro-optical properties of the polymer dispersed liquid crystal (PDLC) prepared by using the microcapsules was highly improved. In particular, the threshold voltage was lowered and the switching behaviour with an applied electric field was sharpened drastically compared with PDLC prepared simply by solvent evaporation-induced phase separation.

Preparation of mono-sized PMMA/liquid crystal microcapsules by solute co-diffusion method

Highly mono-sized polymer/liquid crystal (LC) microcapsules were prepared by solute co-diffusion method (SCM). This new approach employs an impressive process in which LC dissolved freely in a solvent is diffused into the pre-existing mono-sized polymer particles in the form of a fine emulsion. The solvent is then eliminated. The incorporation of LC/solvent emulsions into the substrate polymer particle is completed at 10 °C within 1 h. After solvent evaporation, polymer microcapsules loading a single LC domain are obtained. The morphology depends largely upon the chain characteristics of the substrate polymer particles. When using crosslinked polymer particles, all the microcapsules recovered were of uniform size and spherical in shape.

New Approach To Produce Monosized Polymer Microcapsules by the Solute Co-diffusion Method

This study introduces a new approach for producing highly monosized polymer microcapsules. The technique employs an impressive process in which the solute, dissolved freely in a solvent, is diffused uniformly into the preexisting monosized polymer particles in the form of a fine emulsion. The solvent is then eliminated, resulting consequently in solute-loaded polymer microcapsules. We named it a solute co-diffusion method, SCM. The loading efficiency of the solute was predicted successfully by a thermodynamic equation. In the experiment, the indomethacin-loaded poly(methyl methacrylate) microparticles were produced via SCM. From our results, SCM is expected to expand significantly the drug-loading technology in related fields.