Sulfonated poly (ether ether ketone) (SPEEK) membranes with various degrees of sulfonation (DS) were prepared. Their proton conductivity and methanol permeability as a function of temperature were investigated. It was found that the proton conductivity of SPEEK membranes exceeded 10-2S/cm above 80℃, which is close to that of Nafion® 115 membrane under the same condition. The methanol permeability of SPEEK membranes was about an order of magnitude lower than that of Nafion® 115 membrane. The direct methanol fuel cell (DMFC) performance of the SPEEK membranes was better than that of Nafion® 115 membrane at 80℃

The effect of hydrostatic pressure on the swelling of temperature-sensitive gels was studied by measuring the volume change of the beads of poly (N-isopropylacrylamide) gel, poly (N-n-propylacrylamide) gel, and poly (N, N-diethylacrylamide) gel under pressure up to 120atm. The excess enthalpy and the excess volume of the gel-water systems during the volume phase-transition of the gels were measured. These measurements are helpful in understanding that the pressure sensitivity of these gels originates from their temperature sensitivity and is the consequence of the increase of their LCST with pressure. An equation relating the LCST of the temperature-sensitive gel to the pressure was obtained through thermodynamical analysis. These efforts contribute to reveal the interdependence between the pressure sensitivity and the temperature sensitivity of hydrogel. Copyright.

The enzymeβ-galactosidase was entrapped in poly (N-isopropylacrylamide) gel. The gel swelled or collapsed sharply upon the rise or fall of environmental pressure. The gel beads, prepared by reverse suspension polymerization, were placed in a stirred batch reactor filled with a solution of the substrate o-nitrophenol β-D-galactopyranoside. Operations under constant or cycling pressure were performed. A considerable increase in conversion rate was observed under pressure cycling operation, compared with isobaric operations at either atmospheric or high pressure. This result could be explained by the enhancement of mass transfer inside the gel beads during the pressure cycling operation.

The membranes in direct methanol fuel cells must both conduct protons and serve as a barrier for methanol. Nafion, the most common fuel cell membrane, is an excellent conductor but a poor barrier. Polyvinyl alcohol pervaporation membranes are good methanol barriers but poor conductors. These and most other pervaporation membranes offer no significant advantages over Nafion in methanol fuel cell applications. However, polybenzimidazole membranes have demonstrated characteristics that suggest up to a 15-fold improvement in direct methanol fuel cells. This improvement may be due to an alternate form of proton conduction in which protons travel via a Grotthus or "hopping" mechanism.