Study of facilitated potassium ion transfer across a water vertical bar 1,2-dichloroethane interface using different phase volume ratio systems

A study of potassium ion transfer across a water \ 1,2-dichloroethane (W \ DCE) interface facilitated by dibenzo-18-crown-6 (DB18C6) with various phase volume ratio systems is presented. The key point was that a droplet of aqueous solution containing a redox couple, Fe(CN)(6)(3-)/Fe(CN)(6)(4-), with equal molar ratio, was first attached to a platinum electrode surface, and the resulting droplet electrode was then immersed into the organic solution containing a hydrophobic electrolyte to construct a platinum electrode/aqueous phase/organic phase system. The interfacial potential of the W \ DCE within the series could be externally controlled because the specific compositions in the aqueous droplet make the Pt electrode function like a reference electrode as long as the concentration ratio of Fe(CN)(6)(3-)/Fe(CN)(6)(4-) remains constant. In this way, a conventional three-electrode potentiostat can be used to study the ion transfer process at a liquid \ liquid (L \ L) interface facilitated by an ionophore with variable phase volume ratio (r = V-o/V-w). The effect of r on ion transfer and facilitated ion transfer was studied in detail experimentally. We also demonstrated that as low as 5 x 10(-8) M DB18C6 could be determined using this method due to the effect of the high phase volume ratio.

The glass transition temperatures of PS/PPO blends: Couchman volume-based equation and its verification

The glass transition temperatures (T-g) of PS/PPO blends with different compositions were studied under various pressures by means of a PVT-100 analyzer. A general relation of T-g and pressure of the PS/PPO system was deduced by fitting the experimental T-g's. Couchman volume-based equation was testified with the aid of those data. It was found that the experimental T-g's do not obey the Couchman equation of glass transition temperature based on thermodynamic theory. According to our studies, the major reason of the deviation is caused by the neglect of DeltaV(mix). (C) 2001 Published by Elsevier Science Ltd.