Ching-Chung Chen

Preparation of water-resistant antifog hard coatings on plastic substrate.

A novel water resistant antifog (AF) coating for plastic substrates was developed, which has a special hydrophilic/hydrophobic bilayer structure. The bottom layer, acting both as a mechanical support and a hydrophobic barrier against water penetration, is an organic-inorganic composite comprising colloidal silica embedded in a cross-linked network of dipentaethritol hexaacrylate (DPHA). Atop this layer, an AF coating is applied, which incorporates a superhydrophilic species synthesized from Tween-20 (surfactant), isophorone diisocyanate (coupling agent), and 2-hydroxyethyl methacrylate (monomer). Various methods, e.g., FTIR, SEM, AFM, contact angle, and steam test, were employed to characterize the prepared AF coatings. The results indicated that the size and the continuity of the hydrophilic domains on the top surface increased with increasing added amount of T20, however, at the expense of hardness, adhesiveness, and water resistivity. The optimal T20 content was found to be 10 wt %, at which capacity the resultant AF coating was transparent and wearable (5H, hardness) and could be soaked in water for 7 days at 25 °C without downgrading of its AF capability.

Preparation and antibacterial test of chitosan/PAA/PEGDA bi-layer composite membranes.

Chitosan/poly(acrylic acid)/poly(ethylene glycol) diacrylate (PEGDA) composite membranes with a bi-layer configuration were prepared and their potential application as an antibacterial material was examined. A two-step process was adopted. A dope consisting of PEGDA, acrylic acid (AA) and a photoinitiator was cast and then UV-cured on a glass substrate to form a mechanically strong, dense membrane. Subsequently, the membrane was coated with a layer of solution composed of chitosan, AA and water. As the majority of AA diffused downwards into the supporting layer underneath, chitosan coagulated with residual AA to form a nano-layer on the top surface by means of UV irradiation. Low-voltage field-emission scanning electron microscopy was used to observe the membrane morphology and to measure the thickness of the top layer. Contact angle measurements indicated a top layer mixed with chitosan and poly(acrylic acid), which was confirmed by chemical composition analysis of X-ray photon spectroscopy. The antibacterial activities of the formed membranes were tested both with respect to a Gram-negative (Escherichia coli) and a Gram-positive (Staphylococcus aureus) bacteria.

Observation of Nano-Particles in Silica/poly(HEMA) Hybrid by Electron Microscopy

The sol–gel method was employed to prepare an inorganic–organic hybrid, silica/poly(HEMA). The chemical structure of this material was analyzed by means of FTIR and solid 29Si-NMR. Using TEM and low voltage FESEM imaging at high magnifications (e.g., 300 KX), the hybrid was found to comprise nano-particles whose sizes fall largely over the range 20–30 nm.

Recycle effects on solvent extraction through concurrent-flow parallel-plate membrane modules

Abstract The recycle effects on membrane extraction through a parallel-plate module with concurrent-flow first and then countercurrent flow, has been studied. Theoretical predictions are in agreement with the experimental results. Considerable improvement in performance is obtainable if membrane extraction is operated with recycle which provides the effect of increasing fluid velocity, resulting in decreased mass-transfer resistance. The influences of recycle type on the performance of membrane extraction, as well as on the fixed and operating costs, have been also discussed.

Preparation of polymer/silica composite antiglare coatings on poly(ethylene terphathalate) (PET) substrates

Abstract3-(Trimethoxysilyl) propyl methacrylate and fluoroalkylsilane modified silica particles were UV-cured with the multifunctional crosslinking agent, dipentaerythritol hexaacrylate (DPHA), to prepare antiglare (AG) coatings that exhibit high hardness. Modified silica was used to impart surface roughness whereas DPHA was used to provide hardness and adhesiveness. The formed AG coatings were characterized in terms of topological, optical, and mechanical properties. It was found that with the increase of DPHA content in the coatings, the surface roughness and haze decreased while the gloss and clarity increased. For samples containing 40 and 50 wt% DPHA, the optical properties are comparable to commercial AG products for flat panel display and touch panels. These prepared coatings also demonstrate high hardness of 5–6H and 100% adhesion on poly(ethylene terphathalate) substrates.

Effects of recycle type on solvent extraction through a parallel-plate membrane module

Abstract The effects of recycle type on membrane extraction through a parallel-plate module has been studied. Theoretical predictions are in fairly good agreement with the experimental results. Considerable improvement in mass-transfer is obtainable if membrane extraction is operated with recycle which provides the effects of pre-extraction and increasing fluid velocity. The influences of recycle type on the performance of membrane extraction, as well as on the fixed and operating costs, have been also discussed.

Solvent extraction in cross-flow multipass parallel-plate membrane modules of fixed configuration

Abstract The effect of multipass arrangement on membrane extraction through a cross-flow rectangular module has been investigated both theoretically and experimentally. In contrast to a single-pass device, improvement in mass transfer is obtained if cross-flow membrane extraction is operated in a multipass device of same configuration. It is concluded that multipass effect which provides the increase of fluid velocity, can enhance mass transfer, especially for concentrated solution with high distribution coefficient where the liquid-phase mass-transfer resistances are more extremely predominant.