Resistance of transparent latex films based on acrylic latexes encapsulated with a polypyrrole shell

We have prepared films with a transparency of more than 90% and a resistance in the antistatic range from 1 wt.% polypyrrole-encapsulated latexes (PPy-encapsulated latexes) by a heat treatment at:120 degreesC for several hours. The initial film resistance is below 1 M Omega/ rectangle, but after a temporary decrease in resistance upon increasing the film temperature, the film resistance increases strongly. A clear relationship between the temperature and the stability of the film resistance is demonstrated. It is shown that the increase in film resistance upon heating can: be limited by the incorporation of a more stable counter-anion, like p-toluenesulfonic acid or by performing the heat treatment in an inert atmosphere. The p-toluenesulfonic acid has been incorporated by two different methods: directly in the in situ synthesis of the PPy shell or later via ion exchange. The direct incorporation of the stable counteranion has a more positive influence on the resistance stability, but a drawback of this method is that the risk of pure PPy particle formation apart from the core-shell latex particles is found to increase. (C) 2001 Elsevier Science B.V. All rights reserved.