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Further studies on styrene/styrene derivative copolymerizations using combined diphenylzinc‐additive initiator systems
Author(s) -
Rabagliati Franco M,
Pérez Mónica A,
Rodríguez Francisco J,
Caro Carlos J,
Crispel Nicolás
Publication year - 2005
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.1714
Subject(s) - metallocene , cationic polymerization , polymerization , styrene , polymer chemistry , copolymer , methylaluminoxane , monomer , chemistry , post metallocene catalyst , materials science , polymer , steric effects , coordination polymerization , alkyl , radical polymerization , organic chemistry
Abstract A combination of diphenylzinc, a metallocene and methylaluminoxane (Ph 2 Zn‐metallocene‐MAO) is a suitable initiator system for the polymerization of styrene and for its copolymerization with para ‐alkyl substituted styrenes. This paper reports new experimental results which reinforce our previous findings indicating that polymerization processes are initiated by monomer coordination to active species resulting from these particular combined systems. Polymerization propagates by a cationic pathway. Further to our previous observation that the I+ inductive effect of para ‐substituents in styrene improves conversion to polymer, we now find that methyl substitution on the vinyl double bond of styrene, in spite of the I+ inductive effect and as a result of increased steric hindrance, makes the polymerization process difficult. On the other hand, the replacement of titanocenes by zirconocenes or hafnocenes generates Ph 2 Zn‐metallocene‐MAO initiator systems which are also able to induce homo‐ and copolymerization, but with lower yields and producing practically amorphous polymers. The efficiency of our Ph 2 Zn‐metallocene‐MAO initiator systems follows the order titanocene > zirconocene > hafnocene, at least for the studied metallocenes. Copyright © 2004 Society of Chemical Industry