POLYSTYRENE (1) POLY(BUTYL ACRYLATE/AMIDE TYPE FUNCTIONAL MONOMER) (2) 2-STAGE EMULSION POLYMERS - SYNTHESIS AND THERMOMECHANICAL PROPERTIES OF LATEX FILMS/

Polystyrene (PS) (1)/Poly (n-butyl acrylate (BA)/amide type functional monomer) (2) structured latex particles were prepared through emulsio n polymerization varying the hydrophilicity of the functional monomer employed. The second-stage polymerization kinetics, the size and morph ology of latex particles, and the location of the functional groups in the final latexes were studied, in order to relate them to the thermo mechanical properties of films cast from these latexes. It has been sh own that, as expected, increasing the hydrophobicity leads to a better homogeneity in the copolymer formed during the second-stage polymeriz ation, while the more hydrophilic functional monomer partly homopolyme rizes in a separate phase. However, the functionalization by ail the m onomers used in this work, prevents the PS seed particles to form a co ntinuous skeleton (percolated network). Further heat treatments at 140 degrees C do not lead to the formation of a continuous PS phase as fo r pure BA/pure PS two-stage particles. In addition, some thermally ind uced crosslinking effects are discussed in relation with the functiona l monomer location within the particles. (C) 1995 John Wiley & Sons, I nc.