Sodium Hydride/Trialkylaluminum Complexes for the Controlled Anionic Polymerization of Styrene at High Temperature

✍ Scribed by Stéphane Carlotti; Stephane Menoret; Philippe Desbois; Norbert Nissner; Volker Warzelhan; Alain Deffieux

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 128 KB
• Volume: 27
• Category: Article
• ISSN: 1022-1336
• DOI: 10.1002/marc.200600176

✦ Synopsis

Abstract

Summary: A new generation of anionic initiators (butyllithium free), based on trialkylaluminum and a readily available alkali metal hydride, has been developed for the control of styrene polymerization at high temperature. Triisobutylaluminum and sodium hydride form heterocomplexes that are efficient for the initiation of styrene polymerization at 100 °C in toluene or in bulk. To be active under such conditions, these systems require the presence of an excess of metal hydride with respect to AlR~3~ ([Al]/[Na] < 1). PS chains are specifically initiated by the hydrides coming from NaH, and molar masses are controlled in the range 0.8 < [Al]/[Na] < 1. Fast exchange between dormant 1:1 and active 1:2 complexes (Al:Na), and ligand rearrangements within the 1:2 complex, can explain the observed results.

Initiation of styrene with i‐Bu~3~Al/NaH systems.

magnified imageInitiation of styrene with i‐Bu~3~Al/NaH systems.