Mary Donnabelle L. Balela

Growth of Ultralong Ag Nanowires by Electroless Deposition in Hot Ethylene Glycol for Flexible Transparent Conducting Electrodes

High aspect ratio silver (Ag) nanowires with an average length of 25.4 μm and diameter of 102.8 nm were successfully prepared by electroless deposition in hot ethylene glycol (160°C) for 1 h in the presence of PVP. It was found that both PVP concentration and molecular weight significantly influence the morphology and yield of Ag nanowires in solution. Using PVP MW = 55,000, addition of lower amounts of PVP led to formation of large irregularly shaped Ag particles together with a few rod-like structures. Increasing PVP concentration generally resulted in longer and thinner Ag nanowires. On the other hand, low molecular weight PVP produced spherical Ag particles even at high PVP concentration. Ag nanowire flexible transparent conducting electrodes attained a sheet resistance of about 92.5 Ω/sq at an optical transmittance of about 79.6% without any heat treatment. In addition, no significant change in optical and electrical properties was observed after several cycles of bending and adhesion test.

Creation of hydrophobic surfaces using a paint containing functionalized oxide particles

Hydrophobic surfaces were created by coating various substrates (aluminum sheet, soda-lime glass, silicon carbide polishing paper, glass with double-sided adhesive) with paint containing functionalized oxide particles. The paint was created by functionalizing oxide particles (ground ZnO, TiO2 nanoparticles, or TiO2 microparticles) with fluorosilane molecules in absolute ethanol. Water contact angle of samples shows that the coated substrate becomes hydrophobic (water contact angle ≥ 90°). Among the oxides that were used, ground ZnO yielded contact angle exemplifying superhydrophobicity (water contact angle ≥ 150°). Scanning electron micrograph of paint-containing TiO2 nanoparticles shows rough functionalized oxides structures which probably increase the hydrophobicity of the surface.

Removal of methyl orange dye and copper (II) ions from aqueous solution using polyaniline-coated kapok (Ceiba pentandra) fibers

Hollow tubular structured kapok fibers (Ceiba pentandra) were coated with polyaniline (PANI) molecules using an in situ oxidative polymerization technique. The tubular morphology of the kapok fibers was retained after PANI coating. The Fourier transform infrared (FT-IR) spectrum of the PANI-coated kapok fibers illustrated the vibration modes associated with the presence of PANI molecules. The PANI-treated kapok fibers achieved complete wettability with water molecules (zero water contact angle) from initially being highly hydrophobic (contact angle = 120°). In the present work, the removal of contaminants such as methyl orange dye and Cu(II) from aqueous solution using polyaniline-coated kapok fibers was investigated. Isotherm studies show that the removal of methyl orange dye (R2 ≥ 0.959) and Cu(II) (R2 ≥ 0.972) using PANI-coated kapok fibers follow the Langmuir isotherm model with maximum sorption capacities determined to be 75.76 and 81.04 mg/g, respectively. Based from thermodynamic studies, the sorption of methyl orange dye and Cu(II) are endothermic, feasible and spontaneous. Furthermore, kinetic studies show that the both processes follow a pseudo-second-order model, implying that the rate-determining step is chemisorption.

Fabrication of polyaniline-coated Kapok (Ceiba pentandra) fibers embedded with copper-based particles

Polyaniline-coated kapok (Ceiba pentandra) fibers that were embedded with Cu-based particles were fabricated for antimicrobial application. Kapok fibers were coated with polyaniline molecules using oxidative polymerization. The coated fibers were embedded with copper-based particles using soaking method in prepared CuO suspension. X-ray diffraction (XRD) pattern shows presence of Cu and Cu2O particles on the modified fibers. Scanning electron microscopy (SEM) supports the presence of embedded particles on the modified fibers. The samples showed antimicrobial activity against Escherichia coli and Staphylococcus aureus.

Antibacterial activity of copper-based particles synthesized using an electroless deposition technique

Copper-based particles were synthesized using an electroless deposition technique. The said synthesis was done in an aqueous solution by reducing copper oxide powders using hydrazine. In this technique, gelatin was used as protective agent. X-ray Diffraction (XRD) measurement shows that the synthesized sample is composed of cuprous oxide (Cu2O) and copper (Cu) particles. Scanning Electron Microscopy (SEM) shows the morphology of the synthesized copper-based particles. Antimicrobial test shows that the number of Escherichia coli organisms reduced to 62.06% after 2 minutes of contact with the sample. Likewise, SEM micrographs of the Escherichia coli organisms show that the said organism underwent morphological changes in the presence of the synthesized copper-based particles.