Syndiotactic–Atactic Stereoblock Polystyrene Obtained with a Hapto-Flexible Catalyst

Autor:	Annaluisa Mariconda, Mariagrazia Napoli, Pasquale Longo, Luciana D'Urso
Rok vydání:	2014
Předmět:	chemistry.chemical_classification Materials science Polymers and Plastics Organic Chemistry Methylaluminoxane Ether Polymer Styrene Inorganic Chemistry chemistry.chemical_compound Cyclopentadienyl complex chemistry Polymerization Tacticity Polymer chemistry Materials Chemistry Polystyrene
Zdroj:	Macromolecules. 47:2214-2218
ISSN:	1520-5835 0024-9297
DOI:	10.1021/ma500134h
Popis:	Half-titanocene (CpCH2CH2OCH3)TiCl3 (1), (Cp = cyclopentadienyl), activated by methylaluminoxane (MAO), has been tested in the polymerization of styrene in a suitable range of temperatures, obtaining a new material consisting of syndiotactic–atactic stereoblocks of polystyrene. The monoanionic bidentate ancillary ligand of the titanium based catalyst, consisting of a cyclopentadienyl bearing an alkyl ether, is a hapto-flexible ligand because the ether group can either be coordinated or not to the metal, depending on reaction temperature. Thus, the ether group can give rise to two possible catalytic sites: (i) syndiospecific, when the ether group is not coordinated to the metal center, and (ii) aspecific, when it is coordinated to titanium. Consequently, it produces polymer chains having syndiotactic and atactic stereoblocks. In fact, in the range of temperature considered (0–19 °C), syndiotactic polystyrene was produced at 19 °C, atactic polystyrene at 0 and 5 °C, and syndiotactic–atactic stereoblock poly...
Databáze:	OpenAIRE
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