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The kinetics of the early stage of dispersion polymerization in supercritical CO 2 as monitored by turbidimetric measurements, 1. Method
Author(s) -
Fehrenbacher Ulrich,
Muth Oliver,
Hirth Thomas,
Ballauff Matthias
Publication year - 2000
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(20000801)201:13<1532::aid-macp1532>3.0.co;2-z
Subject(s) - supercritical fluid , kinetics , dispersion polymerization , polymer chemistry , polymerization , dispersion (optics) , stage (stratigraphy) , chemistry , materials science , chemical engineering , polymer science , polymer , organic chemistry , optics , physics , geology , engineering , quantum mechanics , paleontology
We present a study of the dispersion polymerization of methyl methacrylate in supercritical carbon dioxide in the presence of poly(dimethylsiloxane)‐monomethyl acrylate. The heterogeneous polymerization is followed in situ by turbidity at a pressure of 330 bar and a temperature of 60°C. The turbidity spectra of the system are measured directly in the autoclave to give the average‐number of particles per unit volume N av / V and the average‐diameter σ τ of the particles as function of time. The experimental setup presented here allows to study the early stage of the nucleation and formation of particles. The results indicate that N av / V increases first and then saturates whereas σ τ increases steadily during this period. A comparison of the rate of polymerization thus obtained with kinetic data measured in bulk, suggests that the formation of particles proceeds through coagulation of the polymer which is formed in the homogeneous phase.