FILMOGENE DISPERSIONS OF COPOLYMER LATEX MODELS - SYNTHESIS-STRUCTURE-PROPERTIES RELATIONSHIPS

This is a review paper of the work carried out by the group of laboratories in a C.N.R.S. program "Film forming Dispersions". Three series of copolymers of styrene, butylacrylate and methacrylic acid have been prepared and characterized (size and surface properties). One is according to a core-shell procedure in two steps (polystyrene seed) in the presence of zwitterionic surfactant, the second in three steps from an inverse core shell procedure practically without surfactant and the third in the presence of polystyrene-polyethylene oxide block copolymers as surfactants. The mechanism of coalescence of latex from the second series was studied first inside a water bath demonstrating the effect of capillary forces alone, and then with water evaporation where the driving force comes from the water evaporation process. New techniques were applied to study various steps of the coalescence process: differential scanning calorimetry and microwave spectroscopy are able to follow the vaporization of free and linked water while neutron scattering experiments show the transcient formation or ordered colloidal crystals and a phase separation process in two phases with inclusion of polymers particle in water or with inclusion of hydrophilic membranes and islands in a continuous polymer phase. Finally dynamic micromechanical properties of the films are studied showing their reinforcement by a honeycomb network from the superficial methacrylic acid copolymers and the trend of the initial polystyrene seed particles to make clusters big enough to percolate upon thermal and/or mechanical treatments.