The synthesis of diene and vinyl copolymers containing predetermined quantities of polynuclear hydrocarbon or heterocyclic adducts—VII: Copolymers formed from butadiene, a heterocyclic compound and some linking or terminating agents

Abstract

The reaction of butadiene (M) and a suitable heterocyclic molecule (A) (acridine, quinoline or puridine) with lithium metal in tetrahydrofuran (THF) produced polymeric adducts of structure − A— M n — A − where the negative charges are located on the nitrogen atoms. Similar products (mono or difunctional) may be produced by reacting living polybutadiene directly with these heterocyclic molecules. In the case of acridine, proton termination produced oligomers terminated with dihydroacridine groups; polymeric species containing amide linkages can be produced by titration with adipoyl chloride and, although this reaction is in itself efficient, the product easily re-aromatizes. With quinoline and pyridine, the dihydroadducts become progressively less stable, showing strong tendencies to re-aromatise and crosslink. It is shown that the anionic pyridine adduct of polybutadiene may be cleanly re-aromatised to produce pyridine-terminated polymers which are stable. These pyridine groups can be reacted with benzyl halides to produce pyridinium salts; the presence of these ionic groups has a profound effect on the physical properties of the product. Reaction with p-xylylene dibromide converts low molecular weight difunctional pyridine-terminated polybutadiene from a mobile liquid to a rubbery solid; the material remains soluble and so is free from chemical crosslinks.