Controlled radical polymerization at pressures up to 2000 bar

Kontrollierte radikalische Polymerization bis zu Drücken von 2000 bar

by Eric Minaux
Doctoral thesis
Date of Examination:2001-05-01
Date of issue:2001-07-26
Advisor:Prof. Dr. Michael Buback
Referee:Prof. Dr. Karlheinz Hoyermann
Persistent Address: http://dx.doi.org/10.53846/goediss-2205

 

 

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Abstract

English

High-pressure controlled polymerizations of styrene and of butyl acrylate were successfully performed using different nitroxides as mediator. Narrow polydispersities and molecular weights close to the theoretical predictions are observed, irrespective of the applied pressure. High pressure allows for a significant enhancement of polymerization rate. High pressure also allows to carry out CRP at relatively low temperature and allows to produce high-molecular-weight material with narrow polydispersity. Rate coefficients were estimated by simulations using the software package PREDICI®. Attempts to control high-pressure ethene polymerization were not successful. Even at fairly high temperature, the dormant species will not readily dissociate. Further increase of temperature is associated with mediator decomposition and with a large enhancement of transfer to monomer reactions. Both effects exclude CRP. PREDICI® simulations and ab-initio calculations allow for the estimation of bond dissociation energies in alkoxyamines. It turns out that in several cases the N-O bond is less stable than the C-O bond which also destroys control of ethene polymerization.
Keywords: high pressure; nitroxide; ethen; TEMPO; SG1; styrene; controlled radical polymerization; CRP
Schlagwörter: Hochdruck; Nitroxide; Ethen; TEMPO; SG1; Styrol; kontrollierte radikalische Polymerization
 
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