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Phase Behavior and Particle Formation of Poly (1H,1H‐dihydrofluorooctyl Methacrylate) in Supercritical CO 2
Author(s) -
SantoyoArreola José G.,
VásquezMedrano Rubén C.,
RuizTreviño Alberto,
LunaBárcenas Gabriel,
Sanchez Isaac C.,
OrtizEstrada Ciro H.
Publication year - 2009
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200950930
Subject(s) - materials science , supercritical fluid , nucleation , polymer , lower critical solution temperature , particle size , thermodynamics , hildebrand solubility parameter , solubility , chemical engineering , surface tension , saturation (graph theory) , polymer chemistry , chemistry , composite material , copolymer , physics , engineering , mathematics , combinatorics
The poly(1H,1H‐dihydrofluorooctyl methacrylate) behavior in supercritical CO 2 was determined in relation to the emulsions formation phenomena in surfactants including a CO 2 ‐philic chain and the particles formation process by RESS. The stability conditions show an obvious influence of both the polymer molecular weight and the CO 2 density, which are in competence with the thermal effect. The results are consistent with a LCST behavior in function of the molecular weight reaching the θ condition that converges for both the upper critical solution (UCSD) and the critical flocculation density (CFD) for a colloidal system. By using Sanchez‐Lacombe equation of state, a solubility parameter is estimated and it confirms the affinity of the fluorinated polymer with CO 2 , this in agreement with the literature information that relates surface tension with cohesion energy. In the particles formation by RESS, it was determined that concentration, saturation degree and nozzle diameter have a direct influence on the particle morphology and size; meanwhile, temperature and pre‐expansion pressure are variables used to tune of saturation degree dependent phase behavior. Results show that particles of 200–400 nm can be obtained when 1%wt polymer, homogeneous solution and 130 µm nozzle diameter are used. Under those conditions, the nucleation process and the particles growth and size during precipitation can be controlled; the mechanism is analyzed in relation to the phase behavior.