Critical Points in Binary Copolymerization and the Penultimate Group Effect

Abstract

In order to examine the influence that a penultimate group effect can have on the number and magnitude of critical points ( azeotropic compositions) in binary copolymerization an expression for the critical point(s) has been derived. Analysis of this relationship shows that in a situation where one critical point would have been expected on the basis of terminal-model kinetics (no penultimate group effect) a modest penultimate group effect can mean that zero, one or three critical points may exist, or, in systems where no critical points would have been predicted, two critical points may exist.