Enthalpy-Driven Ring-Opening Polymerization of Highly Strained Macrocyclic Biaryl-Ether-Ketones

Highly strained macrocyclic ether−ketones obtained by nickel-catalyzed cyclization of linear precursor oligomers undergo ring-opening polymerization via ether exchange in the presence of nucleophilic initiators such as fluoride or phenoxide anions. Strain enthapies of these macrocycles, from DSC ana...

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Bibliographic Details
Published in:Macromolecules 2005-12, Vol.38 (25), p.10421-10428
Main Authors: Colquhoun, Howard M, Zhu, Zhixue, Dudman, Christopher C
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Organic polymers
Physicochemistry of polymers
Polymerization
Preparation, kinetics, thermodynamics, mechanism and catalysts
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Summary:Highly strained macrocyclic ether−ketones obtained by nickel-catalyzed cyclization of linear precursor oligomers undergo ring-opening polymerization via ether exchange in the presence of nucleophilic initiators such as fluoride or phenoxide anions. Strain enthapies of these macrocycles, from DSC analyses of their exothermic ring-opening polymerization are in the range 50−90 kJ mol-1. Melt-phase polymerization generally affords slightly cross-linked materials, but solution-phase polymerization at high macrocycle concentrations gives fully soluble, high molar mass polymers with inherent viscosities of up to 1.78 dL g-1. Sequence-analysis of the resulting polymers by 13C NMR shows that alternating or random monomer sequences may be obtained, depending on whether one or both aromatic rings adjacent to the ether linkages are activated toward nucleophilic attack.
ISSN:0024-9297
1520-5835
DOI:10.1021/ma051781x