Dyeable Hydrophilic Surface Modification for PTFE Substrates by Surface Fluorination

Pluronic P123/DMSO Lyotropic Liquid Crystal for Incorporating Bioactive Substances for Topical Application

Lyotropic liquid crystals (LLCs) have attracted considerably growing interest in drug delivery applications over the last years. The structure of LLC matrices is complementary to cell membranes and provides an efficient, controlled, and selective release of drugs. In this work, a complex of experimental methods was used to characterize binary LLCs Pluronic P123/DMSO and triple LLC systems Pluronic P123/DMSO/Ibuprofen, which are interesting as transdermal drug delivery systems. Liquid crystalline, thermal, and rheological properties of LLCs were studied. Concentration and temperature areas of the lyomesophase existence were found, and phase transition enthalpies were evaluated. Intermolecular interactions among the components were studied by infrared (IR) spectroscopy. In vitro studies of Ibuprofen (Ibu) release from various LLCs allow differentiation of its release depending on the polymer content. Atomic force microscopy and contact angle methods were used to characterize the surface morphology of the hydrophobic membrane, which was used as a stratum corneum model, and also evaluate the adhesion work of the LLCs. A complex analysis of the results provided by these experimental methods allowed revealing correlations between the phase behavior and rheological characteristics of the LLCs and release kinetics of ibuprofen. The proposed biocompatible systems have considerable potential for a transdermal delivery of bioactive substances.

Effect of Oxyfluorination of PFA-Coated Metal Mesh with Superhydrophobic Properties on the Filtration Performance of SiO2 Microparticles

Recently, semiconductor wastewater treatment has received much attention due to the emergence of environmental issues. Acid-resistant coatings are essential for metal prefilters used in semiconductor wastewater treatment. Perfluoroalkoxy alkane is mainly used as an acid-resistant coating agent, since PFA has inherent superhydrophobicity, water permeability is lowered. To solve this problem, the surface of the PFA-coated metal mesh was treated via an oxyfluorination method in which an injected mixed gas of fluorine and oxygen reacted with the surface functional groups. Surface analysis, water contact angle measurement, and water permeability tests were performed on the surface-treated PFA-coated mesh. Consequently, the superhydrophobic surface was effectively converted to a hydrophobic surface as the PFA coating layer was surface-modified with C-O-OH functional groups via the oxyfluorination reaction. As a result of using simulation solutions that float silica particles of various sizes, the permeability and particle removal rate of the surface-modified PFA-coated stainless-steel mesh were improved compared to those before surface modification. Therefore, the oxyfluorination treatment used in this study was suitable for improving the filtration performance of SiO2 microparticles in the PFA-coated stainless-steel mesh.