An electrochemical cell has been designed for in situ micro-Raman measurements on the polymer membrane in an operating polymer electrolyte cell ͑PEM͒. The method is applicable to studies of both the distribution of water and membrane structure in the working cell environment. An initial study of the water distribution across a Nafion 117 membrane in a cell working as a H 2 /H 2 pump cell at hydrogen flow and currents from 0 to 300 mA/cm 2 is presented. The results show that a hydration profile with a lower water content at the anode forms as current is applied to the cell.A critical part of a polymer electrolyte membrane fuel cell ͑PEMFC͒ and a direct methanol fuel cell ͑DMFC͒ is the polymer membrane electrolyte, which conducts protons from anode to cathode whilst blocking the transfer of electrons and reactants. The membrane material must combine high proton conductivity, low gas permeability, long term stability in the fuel cell environment, and of course low cost. 1 This paper presents a novel method to directly study the working polymer membrane in an operating electrochemical cell using confocal micro-Raman spectroscopy. In the field of proton conducting polymer electrolytes Raman spectroscopy can be used to study issues such as, membrane composition, molecular coordination, and polymer conformation. An added strength is the spatial resolution obtained with confocal micro-Raman spectroscopy, i.e., Raman microscopy, which under optimized conditions is on the level of micrometers both in horizontal and depth directions. The spatial resolution has, for instance, been exploited to map the distribution of functional molecular groups in a membrane 2 or to follow the extent of degradation of fuel cell tested membranes ex situ. [3][4][5] In the fuel cell application, high membrane proton conductivity is one of the key parameters for a good fuel cell performance. Conventional membranes, typically Nafion ͑DuPont͒ and other sulfonated polymers, combine hydrophobic and hydrophilic polymer parts that form a structure, phase separated on a nanometer scale. 6 The hydrophobic phase provides mechanical stability. The hydrophilic phase containing sulfonic acid groups will be proton conducting when sufficiently hydrated. The water content, commonly expressed as ϭ the number of water molecules per sulfonic acid group (H 2 O/SO 3 ), is therefore of great importance. In the range of hydration found in the fuel cell ϭ 2-14, the specific conductivity of Nafion 117 increase nearly an order of magnitude as the water content increases. 7 Proton transport through the membrane leads to a flow of water electro-osmotic drag 8 which is balanced by a concentration gradient induced back flow of water. A number of models describing the water distribution in fuel cell membranes have been put forward. 9,10 A common result of the different models is a depletion of water at the anode with increasing current, however the shape of the modelled concentration gradient varies. During the measurements presented here the cell is working as a hydrogen pu...

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A study has been carried out to investigate controlled release performance of caplet shaped injection moulded (IM) amorphous solid dispersion (ASD) tablets based on the model drug AZD0837 and polyethylene oxide (PEO). The physical/chemical storage stability and release robustness of the IM tablets were characterized and compared to that of conventional extended release (ER) hydrophilic matrix tablets of the same raw materials and compositions manufactured via direct compression (DC). To gain an improved understanding of the release mechanisms, the dissolution of both the polymer and the drug were studied. Under conditions where the amount of dissolution media was limited, the controlled release ASD IM tablets demonstrated complete and synchronized release of both PEO and AZD0837 whereas the release of AZD0837 was found to be slower and incomplete from conventional direct compressed ER hydrophilic matrix tablets. The results clearly indicated that AZD0837 remained amorphous throughout the dissolution process and was maintained in a supersaturated state and hence kept stable with the aid of the polymeric carrier when released in a synchronized manner. In addition, it was found that the IM tablets were robust to variation in hydrodynamics of the dissolution environment and PEO molecular weight.