Quantitative microscopic study of surface characteristics of track-etched membranes

Investigation of conductivity, SEM, XRD studies of Mg2+ ion based TiO2 nanocomposite PVDF-HFP polymer electrolyte and application in a dye sensitized solar cell

The potential effect of nano TiO2 in poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) based polymer electrolyte and their application in a dye sensitized solar cell have been investigated. The solution casting process was used for fabrication of nano TiO2 loaded in Mg 2+ ion based PVDF-HFP solid polymer electrolyte (SPE), and characterized using conductivity, scanning electron microscopy (SEM), X-ray diffraction (XRD) and photovoltaic studies. XRD investigations reveal the broadening of specific peaks, which shows the occurrence of α, β and γ polymorphous phase transitions that commence the amorphous character and ion mobility. The SEM pictures revealed an interconnecting network of micro-porous nature, and an average diameter of the pores of ∼0.38 µm was obtained by using Gaussian curve fitting. Ion transport is facilitated by the high concentration of pores, which is responsible for the efficient absorption of a significant amount of electrolyte. The photovoltaic characteristics of dye sensitized solar cell (DSSC) estimated efficiency (η) is 9.9999%, and the fill factor is 0.84. Furthermore, the stability performance of the nanocomposite polymer electrolyte was improved and sufficient for use over an extended length of time, suggesting potential applications as a separator in solid state ionic conductors.

An electrochemical study of microporous track-etched membrane permeability and the effect of surface protein layers

Microporous track-etched membranes serve as important permeable growth surfaces for cell culture where diffusive solute transport is needed across two growth compartments. This study has established effective solute diffusion coefficients for four probe micro-solutes: hydrogen peroxide, pyrocatechol, acetaminophen and ascorbic acid across three track-etched membranes formulated, respectively, from polycarbonate and polyethylene terephthalate. Chronoamperometry and cyclic voltammetry were used for the diffusion measurements. These showed substantially reduced intra-pore diffusion in relation to available pore area. Diffusion coefficients ranging from 1.43×10^-10 to 3.17×10^-7cm²s^-1 were demonstrated. This strongly suggests that water organisation in micro-pores is not equivalent to that of bulk water. Superimposed protein layers of Type I and IV collagen, Type I collagen-fibronectin, Type I collagen-heparin, and Type I collagen-chondroitin sulphate increased diffusional resistance, but with disproportional retardation of ascorbate diffusion due to charge repulsion at collagen-heparin and collagen-chondroitin sulphate combinations. Diffusive resistance at natural tendon and cartilage was considerably smaller; diffusion coefficients ranged from 8.33×10^-6 to 1.09×10^-8cm²s^-1.