Kinetic study of the heterogeneous anionic coordinated polymerization of ethylene oxide

✍ Scribed by Jean-Pierre Letourneux; Thierry Hamaide; Roger Spitz; Alain Guyot

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 857 KB
• Volume: 197
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1996.021970820

✦ Synopsis

Abstract

New heterogeneous catalytic systems for anionic ring opening polymerization of oxygenated heterocycles are obtained by grafting alkylaluminium moieties on porous silica. Adding alcohol in excess causes the formation of aluminium alkoxides and allows a rapid exchange reaction between the grafted active centers and the free alcohols remaining in the solution, so that more polymer molecules than the number of metal atoms used are produced. An interesting feature is the facility to obtain functionalized oligomers because these exchange reactions lead to polymer chains end‐capped by moieties derived from the alcohol molecules. The kinetic behaviour was investigated for different monomer, alcohol and aluminium concentrations. An activation is observed for a well‐defined alcohol concentration range which is interpreted in terms of the enhancement of the nucleophilic reactivity of the oxygen atom of the alkoxide due to the coordination of the free alcohol onto the active centers and the share of the acidic vacancy of the aluminium atom.