Synthesis and characterization of model carboxylated latexes for studies of film formation from latex blends

摘要

Poly(n-butyl methacylate-co-n-butyl acylate) [P(BMA/BA)] soft latexes (carboxylated and noncarboxylated) were synthesized using a semicontinuous emulsion polymerization process that was designed on the basis of a theoretical calculation to determine the suitable surfactant [i.e., sodium dodecyl sulfate (SDS)], monomer, and water feed rates to maintain a constant particle number throughout the polymerization (guaranteeing monodispersity in the particle size), to obtain a homogeneous copolymer composition, and to independently control the particle size and carboxyl group concentration. The experimental results support the theoretical calculation. The surface coverage of the carboxyl groups present on the soft latex particles ranges from 7.6 to 21.9% for a series of latexes with particle sizes around 120 nm. Tn another series of latexes, the particle size was varied over a range from 120 to 450 nm. Monodisperse carboxylated polystyrene hard latexes were synthesized by shot growth (batch) and semicontinuous processes. The shot growth method is somewhat inflexible in providing more choices in surfactant, particle size, and surface carboxyl coverage. A semicontinuous process designed using a similar method used for the synthesis of P(BMA/BA) latexes successfully eliminated the drawbacks of the shot growth process. In this way, the changes in the surface carboxyl coverage (varies from 0 to 77.2% ) was independent of the particle size, which was precisely controlled by the amount of styrene fed under suitable styrene and SDS feed rates. (C) 2000 John Wiley & Sons, Inc. [References: 20]