Penetrant molecule , transport through

Small molecule transport through nonporous polymers proceeds by the solution-diffusion mechanism. This a three-step mechanism where penetrant molecules... 

While electrochemical experiments provide useful information regarding electron transport through these molecular monolayers, construction of real devices requires formation of a top contact so that solid-state transport measurements can be made. The fabrication of contacts to molecular layers has been the major obstacle to the development of molecular electronic devices, whether based on thiol-based SAMs on gold or covalently attached molecules on silicon. The most popular approach to making contacts involves evaporation of metals onto the molecular layer, which is likely to result in at least partial penetration of the monolayer, and may possibly damage the molecules in the layer. 

As previously discussed, electron, light, and confocal microscopy techniques may be used to visualize the position of electron-dense precipitates, radioactive substances, and fluorescent probes, respectively, in the sample tissue. However, none of these techniques possess the capability both to visualize and to selectively measure the flux of a molecule across the skin. SECM, however, permits the measurement and subsequent imaging of the local flux of an electroactive species across biological membranes. Scott et al. [3] used SECM to investigate the effect of pretreatment of the penetration enhancer sodium dodecyl sulfate (SDS), on the ion transport rate and transport pathways of Fe(CN) across hairless mouse skin. Increasing the time of SDS exposure from 10 min to 30 min increased the overall (porous and nonporous) transport of Fe(CN) by 17-fold. More specifically, the SDS-induced increase in Fe(CN)g transport was found to be associated with nonporous (i.e., intercellular) transport routes, while transport via porous routes was significantly reduced. The fraction of Fe(CN)g transport through pores, as measured by... 

Transport of Penetrant Molecules Through Copolymers of Vinylidene Chloride and... 

The study of the transport of penetrant molecules through polymers [1,2] is important in many areas of technology. There are two types of industrially important polymeric systems for which such transport phenomena are crucial ... 

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