SYNTHESIS OF MODEL LATTICES FOR THE STUDY OF COALESCENCE MECHANISMS

This work describes the synthesis of model latices devoted to the study of the influence of particle-water and particle-air interfacial energies on coalescence mechanisms. Core-shell particles with the same diameter (congruent-to 2600 angstrom) and narrow size distributions were prepared. The core is a poly(styrene-co-butyl acrylate) (60/40 wt %) copolymer; it represents 90% of the volume of the particle. The shell is a poly(St-BuA-methacrylic acid) terpolymer with 10, 15, or 25 wt % MAA. The St-BuA weight ratio in the shell is also 60/40. The amount of MAA in the shell determines the particle-water or air interfacial energies. In order to limit the use of an emulsifier and to ensure a homogeneous particle surface layer, an inverted core-shell synthesis was performed. The hydrophilic shell was prepared first and used as a seed for the synthesis of the hydrophobic core. For all three core-shell latices, about 45% of the introduced MAA was found at the surface of the particles, which indicates that the core-shell inversion was successful. The synthesis of the latices with 10 or 15 wt % MAA was relatively easy, whereas the particle size was difficult to control in the 25 wt % MAA latex synthesis.