Morphological prediction and its application to the synthesis of polyacrylate/polysiloxane core/shell latex particles

A theoretical analysis and a morphological prediction of polyacrylate (PA)/ polysiloxane (PSi) latex particles with core/shell morphologies were first conducted based on interfacial tensions and relative volumes of the two po lymers in the latex system. The results indicated that the normal core/shel l morphology particles (PSi/PA), with hydrophobic polysiloxane as the core and with hydrophilic polyacrylate as the shell, can be easily formed. Altho ugh the inverted core/shell morphology particles (PA/PSi) with polyacrylate as the core could not be formed in most cases, even if the fraction volume of polysiloxane was larger than 0.872, which is the smallest value of form ing a PA/PSi particle, the PSi/PA particles were unavoidably formed simulta neously with PA/PSi particle formation. The synthesis of PA/PSi particles c ontaining equal amounts of polyacrylate and polysiloxane was then carried o ut using seeded emulsion polymerization. Before the cyclosiloxane cationic polymerization, 3-methacryloyloxypropyl trimethoxysilane (MATS) was introdu ced into the polyacrylate seed latex to form an intermediate layer and chem ical bonds between the core and the shell polymers. The characterization by transmission electron microscopy (TEM) demonstrated that the perfect PA/PS i core/shell particle is successfully synthesized when both the core and th e shell polymers are crosslinked. The experiments showed that both the hard ness and water adsorption ratio characteristics of latex films of the PA/PS i particles are in good agreement with those of the polysiloxane film. (C) 2001 John Wiley & Sons, Inc.