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Preparation of Monodisperse Polystyrene Latices by Y-Ray Polymerization and Their Electron-Microscopic and Electrophoretic Characterization

I. Jalšenjak
Gj. Deželić
J. J. Petres
Ž. Telišman

Puni tekst: engleski pdf 14.600 Kb

str. 157-170

preuzimanja: 104



The preparation of monodisperse polystyrene latices by the
initiation with y-rays from ۥ)Co is described. The latices were
prepared by the direct polymerization method in the presence of
the emulsifier Aerosol MA. The latex samples were characterized
with regavd to the particle size, the particle size diskibution, and
the ·surface particle charge by the methods of electron microscopy
and moving boundary electrophoresis. The surface properties of
latex particles were examined on samples exhaustively dialysed
against distilled water and tTeated with ion-exchange resins. The
results were compared with data collected on latices prepared by
persulfate initiation. The latices prepared by y-ray initiated polymerization
proved to have a somewhat smaller particle size and a
higher degree of monodispersity in a wider range of the emulsifier
concentration than those prepared by persulfate initiated polymerization.
Whereas with persulfate initiation monodisperse latices
were obtained at emulsifier concentrations near to the critical
micelle concentration, with irradiation initiation monodisperse
samples were formed at higher emulsifier concentrations. It was
found that the mechanism of polymerization in the presence of
Aerosol MA deviates from those formulated by Smith and Ewart.
From data on electrophoretic mobility of particles the zeta-potentials
and particle surface cha·rge densities for various prepared
latices were calculated. On the basis of measurements of electrophoretic
mobility in relation to pH values of latex suspensions the
character of functional groups which contributed to the total particle
surface charge is discussed.

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