Polar Contribution To Surface Energy Research Articles

Phytic acid layer template-assisted deposition of TiO2 film on titanium: Surface electronic properties, super-hydrophilicity and bending strength

Titanium dioxide film has received a great deal of attention, because of its excellent potentials and implications, in a variety of fields. Practically, the film is required to be well mechanically blended with the substrate (e.g. good compliance or flexibility) together with its surface properties to accomplish multiple functions. In this work, phytic acid (PA) layer template-assisted deposition of thin TiO2 film was implemented on titanium substrate to produce a good combination of surface properties and bending strength. Relatively smooth, homogenous and thin (ca. 800nm) anatase TiO2 films were obtained on the PA pre-templated Ti substrate. Significantly enhanced photoluminescence was observed on the PA template-deposited TiO2 as compared to the direct deposited TiO2. This is correlated with its higher carrier density in the space charge layer as disclosed by the Mott–Schottky investigation. Likewise, the prepared TiO2 films are super-hydrophilic (with water contact angle less than 5°), which is credited to the higher polar contribution of surface energy. Moreover, the PA template-deposited TiO2 film withstood plastic deformation up to 180° angle bending without failure. This template-assisted deposition of TiO2 film via surface-immobilized organic layer on rigid substrate suggests a promising route to enhance both its mechanical and physical performances.

Plasma surface treatment of PCL/PC blend sheets

AbstractSurface treatments using glow discharge plasmas from O2 and Ar were applied to blend sheets of poly(ϵ‐caprolactone)‐polycarbonate (PCL/PC), which had been produced by extrusion from melts of the mixture at various blend ratios. As to the reactivity of these two plasmas, O2‐plasma forms the oxidative species to be reactive in general, while Ar‐plasma is non‐oxidative. Weight loss by the oxidative O2‐plasma etching increased with the content of PCL in the polymer blends. The surface became hydrophilic by plasma treatment, and the changes were affected also by the blend ratio. PC and the PC‐rich blend sheets became more hydrophilic than the PCL‐rich blends after plasma treatments. The O2‐plasma treatments were more effective than non‐oxidative Ar‐plasma treatment in increasing the hydrophilicity. Hydrophilic change was related to the increase in the polar contribution of surface energy.

Biodegradation of poly(ε-caprolactone)–polycarbonate blend sheets

Biodegradation of an extruded sheet of poly(ε-caprolactone) (PCL) and blend sheets with polycarbonate (PC) prepared from the melts at various polymer ratios was investigated. PCL, which is biodegradable in lipase AK and also by burial in soil, became less degraded in the blend with PC. The blend sheets (PCL/PC) were surface-treated with glow discharge plasmas from O 2 and Ar, and the surface became hydrophilic by the treatments. Increase in the polar contribution of surface energy was related with the hydrophilicity. The effects on the biodegradation were different depending on the type of plasma treatments; i.e. oxidative treatments by O 2-plasma increased the enzymatic biodegradation, while the Ar-plasma treatments rather decreased the degradation. The effects on degradation is discussed from the surface phenomena.

Some aspects of plasma copolymerization of acetylene with N2 and/or water

AbstractPlasma polymerizations of mixture of acetylene‐N2, acetylene‐H2O, were investigated by using an electrodeless glow discharge from a 13.5‐MHz radiofrequency source. Properties of plasma polymers were examined as functions of mole ratios of N2 and/or H2O to acetylene. The concentration of trapped free radicals and the internal stress in a plasma polymer decreased as the mole ratio of N2 or H2O increased. Water showed the most pronounced effects in those properties at the mole ratio of 0.3. Gas permeabilities increased by the copolymerization of N2 and/or H2O. Surface energies were also investigated by analysis of contact angles of liquids. Copolymerization of N2 caused a remarkable increase in polar contribution of surface energy. Some fundamental aspects of flow‐rate pressure relationship of mixed gases are presented.