STUDIES ON PERMEATION THROUGH POLYMER LATEX FILMS .2. PERMEATION MODIFICATION BY SUCROSE ADDITION

An investigation of the effect of leachable sucrose on the permeabilit y of polymer latex films showed that the additive can be used to vary the solute permeability in a systematic manner, as a result of increas ed free volume resulting from additive leaching. However, the extent o f the permeability enhancement is dependent on both the glass transiti on temperature of the polymer and its ability to sustain porosity and prevent pore reduction by wet sintering and/or film drying, and also t he compatibility of the sucrose additive with the polymer. The loading of additive dictates how readily it is leached and, hence, the presen ce, or not, of continuous porosity through the full thickness of film. Although continuous porosity can be conferred on the film by the sucr ose leaching, the resulting porosity still greatly inhibits the permea tion of electrolyte, and the film fails well before the level of poros ity approaches that required for unimpeded transport.