Permeation and morphology in polymer latex films containing leachable additives

This paper reviews recent research, performed at The Nottingham-Trent University, into the enhancement of the permeability properties of polymer latex films. Both leachate-free model colloid latices, made by surfactant-free emulsion polymerisation, and commercially available latices, containing surfactants and often requiring plasticiser addition to achieve good film formation, have been studied. Water soluble leachable additives such as sucrose, HPMC and a soluble polymer latex, have been employed to deliberately enhance solute permeant flux, and the transport properties of the films are discussed with reference to film morphology. The use of increasing levels of leachable additive allows the solute transport mechanism to be systematically changed from one in which permeation occurs predominantly by solution-diffusion to a mechanism in which convective diffusion predominates and solute permeation tends to become independent of penetrant solubility in the polymer. The results are discussed in terms of the increased hydration of the polymer resulting from additive leaching.