Polymerization by alkaline earth metal compounds—II Polymerization of 2- and 4-vinylpyridine, styrene and butadiene by triphenylmethyl derivatives of calcium, strontium and barium

✍ Scribed by W.E. Lindsell; F.C. Robertson; I. Soutar

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 475 KB
• Volume: 19
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(83)90024-1

✦ Synopsis

Investigations are reported on polymerizations of 2-and 4-vinylpyridine, styrene and butadiene by a series of related alkaline earth metal initiators, Ph3CMX(THF)° (M = Ca, Ba, X = C1, n -2: M = Ca. X = Br, n = 4; M = St, X = CI, n = 4; M = Sr, X = Br, n = 5) in tetrahydrofuran (THE) or 1,2-dimethoxyethane (DME) at various temperatures and in the absence of solvent. The polymers have been examined by GPC and aspects of their microstructures determined by t3C and/or~H NMR spectroscopy and. for polybutadiene, i.r. spectroscopy. Poly-2-vinylpyridine produced by Ph3CMX(THF), is rich in isotactic content; the isotacticity is higher for polymer formed in THF than DME solution, falls with change of initiator in the order M = Ca > Sr > Ba and, in DME, is greater when X = Br. The tacticities of poly-4-vinylpyridine and polystyrene are similar to those obtained from related organometallic initiators. The 1,4-content of polybutadiene decreases with initiator Ph3CMX(THF). in the order M = Ba > Sr > Ca; the trans-l,4 structure generally predominates except when M = Ba from which cis-l,4 links are formed in comparable amounts.