Terminal-Group Association in Carboxy- and Carboxylate-Terminated Polybutadiene

Abstract

The viscosity of carboxylic-acid-terminated polybutadiene increases markedly upon neutralization with mono- and divalent bases. These viscosity increases are related to apparent molecular weight, considering the association of the terminal salts as ``polymerizing'' the difunctional prepolymer. For the monovalent alkali-metal salts, simple end-group dimerization seems to occur with an average ΔH of ∼−25 kcal/mole. Neutralization with ions of higher valency leads to materials with higher viscosities.