Synthesis of isotactic polystyrene with a rare-earth catalyst

✍ Scribed by Li Liu; Zhi Gong; Yulian Zheng; Xiabin Jing

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 141 KB
• Volume: 36
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199808)36:11<1773::aid-pola10>3.0.co;2-b

✦ Synopsis

Polymerization of styrene with the neodymium phosphonate Nd(P 507 )/H 2 O/ Al(i-Bu) 3 catalytic system has been examined. The polymer obtained was separated into a soluble and an insoluble fraction by 2-butanone extraction. 13 C-NMR spectra indicate that the insoluble fraction is isotactic polystyrene and the soluble one is syndiotactic-rich atactic polystyrene. The polymerization features are described and discussed. The optimum conditions for the polymerization are as follows: [Nd] Å (3.5-5.0) 1 10 02 mol/L; [styrene] Å 5 mol/L; [Al]/[Nd] Å 6-8 mol/mol; [H 2 O]/[Al] Å 0.05-0.08 mol/mol; polymerization temperature around 70ЊC. The percent yield of isotactic polystyrene (IY) is markedly affected by catalyst aging temperature. With increase of the aging temperature from 40 to 70ЊC, IY increases from 9% to 48%. Using AlEt 3 and Al(i-Bu) 2 H instead of Al(i-Bu) 3 decreases the yield of isotactic polystyrene. Different neodymium compounds give the following activity order: Nd(P 507 ) 3 ú Nd(P 204 ) 3 ú Nd(OPr i ) 3 ú NdCl 3 / C 2 H 5 OH ú Nd(naph) 3 . With Nd(naph) 3 as catalyst, only atactic polystyrene is obtained.