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Syndiotactic specific polymerization of styrene: driving energy of the steric control and reaction mechanism
Author(s) -
Longo Pasquale,
Proto Antonio,
Zambelli Adolfo
Publication year - 1995
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.1995.021960924
Subject(s) - tacticity , polymerization , polymer chemistry , monomer , stereospecificity , steric effects , styrene , catalysis , chemistry , reaction mechanism , polymer , activation energy , materials science , copolymer , organic chemistry
The stereoregularity of polystyrenes prepared in the presence of different syndiotactic specific homogeneous catalysts, at different temperatures and monomer concentrations, has been evaluated by 13 C NMR. It is confirmed that the statistical model of the stereospecific propagation is first‐order Markovian. The stereoregularity of the polymers decreases while increasing the polymerization temperature and is affected by the concentration of the monomer, by the ligands of the transition metal precursor of the catalyst, and is higher in the presence of titanium based catalysts. Polymerization of substituted styrenes is increasingly stereospecific in the order p ‐chlorostyrene < styrene < p ‐methylstyrene. The results strongly support the polyinsertion mechanism proposed in a previous paper by some of us.