Hollow‐particle latexes were prepared according to the following stages: (1) the preparation of the methyl methacrylate–methacrylic acid (MAA)–ethylene glycol dimethacrylate copolymer (I) latex, (2) the preparation of a shell (II) based on polystyrene or styrene–acrylonitrile–divinyl benzene copolymer polymerized onto copolymer (I) particles, and (3) the neutralization of the core (I) carboxyl groups with a base (NH4OH or NaOH) at temperatures close to the glass‐transition temperature of the polymer (II). The neutralization resulted in the expansion of the particles and formed water‐filled hollow particles. The microspheres had an overall diameter of 460–650 nm and a hollow diameter of 300–450 nm. Rheological studies and particle size measurements by transmission electron microscopy and dynamic light scattering of the copolymer (I) latex indicate that the maximum particle swelling occurred at an approximately equimolar MAA/base ratio. It was found that even without the neutralization of the MAA units, a small hollow formation in the latex particles occurred during stage 2 because one volume of the copolymer (I) retained about 8 volume parts of water. It was also discovered that the final hollow‐particle geometry after neutralization depends on the shell copolymer thickness and type as well as on the conditions during stage 3, that is, the time, temperature, base type, and concentration. The opacifying ability of the synthesized hollow particles was investigated in latex coatings. The opacifying ability values were generally in agreement with the hollow‐particle geometry. The only exception was related to the copolymer (I)/copolymer (II) ratio. The maximum hollow volume was obtained at this value equal to 1/8, whereas the highest opacifying ability was observed at 1/10. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1435–1449, 2001

ABSTRACT:The influence of organoaluminum compound on kinetic heterogeneity of active sites in lanthanidebased diene polymerization was investigated. It was shown that heterogeneity of investigated catalytic systems was displayed in the existence of four types of active centers. They are formed at the beginning of the polymerization process and produce macromolecules with lengths that are definite for each type of active centers. The organoaluminum compound's nature greatly influences the kinetic activity of polymerization centers. The method of analysis of the curves' maximum distribution on kinetic activity and the change of kinetic activity of every active centers' type were proposed, which permits the calculation of values of concentration for each type of active center separately.

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