Efficiencies of various metallocene/reducing agent catalyst systems in the hydrogenation of polystyrene-b-polybutadiene-b-polystyrene block copolymers
✍ Scribed by Wen-Shen Yang; Henry Chi-Chen Hsieh; Raymond Chien-Chao Tsiang
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 237 KB
- Volume
- 72
- Category
- Article
- ISSN
- 0021-8995
No coin nor oath required. For personal study only.
✦ Synopsis
Various metallocenes, including bis( 5 -cyclopentadienyl)cobalt, bis( 5 -cyclopentadienyl)nickel, and bis( 5 -cyclopentadienyl)titanium dichloride, combined with various reducing agents, including n-butyllithium, phenyllithium, and triethylaluminum, have been evaluated for their catalytic efficiencies in the hydrogenation of polystyrene-b-polybutadiene-b-polystyrene (SBS) block copolymer. The efficiencies were determined by monitoring the extent of saturation of double bonds on the polybutadiene segment of the copolymer using FTIR and 1 H-NMR spectroscopy. The cobaltocene/nbutyllithium catalyst system was found the most active. The effects of H 2 pressure and the ratio of n-butyllithium to cobaltocene ratio on the hydrogenation efficiency were also investigated.