STABILIZED POLYMER MICROPARTICLES BY PRECIPITATION WITH A COMPRESSED FLUID ANTISOLVENT .1. POLY(FLUORO ACRYLATES)

Citation
S. Mawson et al., STABILIZED POLYMER MICROPARTICLES BY PRECIPITATION WITH A COMPRESSED FLUID ANTISOLVENT .1. POLY(FLUORO ACRYLATES), Macromolecules, 30(1), 1997, pp. 71-77
Citations number
48
Categorie Soggetti
Polymer Sciences
Journal title
ISSN journal
00249297
Volume
30
Issue
1
Year of publication
1997
Pages
71 - 77
Database
ISI
SICI code
0024-9297(1997)30:1<71:SPMBPW>2.0.ZU;2-P
Abstract
Poly(1,1-dihydroperfluorooctyl acrylate) (poly(FOA)) based stabilizers greatly reduce, and in some cases eliminate, flocculation of amorphou s poly(methyl methacrylate) (PMMA) and polystyrene (PS) microparticles formed by precipitation into liquid CO2 at 23 degrees C. The micropar ticle stabilization mechanism is explained in terms of the stabilizer- CO2 phase behavior, the spray characteristics, and the interfacial act ivity of the stabilizer. Compared with the homopolymer poly(FOA), the diblock copolymer PS-b-poly(FOA) produces smaller and more spherical p rimary particles (0.1-0.3 mu m) and also prevents flocculation at lowe r stabilizer concentrations. These differences are due to the greater interfacial activity of PS-b-poly(FOA). Steric stabilization commences in the jet on the order of several tenths of milliseconds and continu es for seconds throughout the precipitator. With the use of a coaxial nozzle, precipitation is delayed and the stabilizers become even more effective at preventing flocculation.