Surface modification of PVC films in solvent-non-solvent mixtures

Appropriate reaction conditions for the selective surface modification of P VC films with sodium azide and amino thiophenol were investigated. Whilst t he use of a phase-transfer agent makes it possible for the nucleolphilic su bstitution reaction to occur, the morphology of the film is changed by the reaction, leading to a loss in both surface smoothness and transparency of the film. On the other hand, performing the reaction in mixtures of a good and a non-solvent for PVC modification takes place in a controlled manner a nd the film remains both smooth and transparent. The degree of modification can be varied as a function of time, of temperature and the proportion sol vent to nonsolvent used in the reaction. The determination of the overall d egree of modification of films of different thickness allows one to draw co nclusions about the surface selectivity of the reaction. According to this study, the reaction with sodium azide occurs homogeneously through the film , whilst the use of amino thiophenol leads to a polymer film which is prefe rentially modified at the surface. (C) 2000 Elsevier Science Ltd. All right s reserved.