1. 'STYRENE/1,3-BUTADIENE COPOLYMERIZATION BY C2-SYMMETRIC GROUP 4 METALLOCENES BASED CATALYSTS.'
- Author
-
Rosa Ricciardi, Antonia Memoli, Pasquale Longo, and Mariagrazia Napoli
- Subjects
Polymers and Plastics ,Comonomer ,Organic Chemistry ,Diad ,1,3-Butadiene ,Mole fraction ,Styrene ,chemistry.chemical_compound ,chemistry ,Tacticity ,Polymer chemistry ,Materials Chemistry ,Copolymer ,Metallocene - Abstract
C2-symmetric group 4 metallocenes based catalysts (rac-[CH2(3-tert-butyl-1-indenyl)2]ZrCl2(1), rac-[CH2(1-indenyl)2]ZrCl2(2) and rac-[CH2(3-tert-butyl-1-indenyl)2]TiCl2(3)) are able to copolymerize styrene and 1,3-butadiene, to give products with high molecular weight. In agreement with symmetry properties of metallocene precatalysts, styrene homosequences are in isotactic arrangements. Full determination of microstructure of copolymers was obtained by 13C NMR and FTIR analysis and it reveals that insertion of butadiene on styrene chain-end happens prevailingly with 1,4-trans configuration. In the butadiene homosequences, using zirconocene-based catalysts, the 1,4-trans arrangement is favored over 1,4-cis, but the latter is prevailing in the presence of titanocene (3). Diad composition analysis of the copolymers makes possible to estimate the reactivity ratios of copolymerization: zirconocenes (1) and (2) produced copolymers having r1 × r2 = 0.5 and 3.0, respectively (where 1 refers to styrene and 2 to butadiene); while titanocene (3) gave tendencially blocky styrene–butadiene copolymers (r1 × r2 = 8.5). The copolymers do not exhibit crystallinity, even when they contain a high molar fraction of styrene. Probably, comonomer homosequences are too short to crystallize (ns = 16, in the copolymer at highest styrene molar fraction). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1476–1487, 2008
- Published
- 2008