Molecular mass distributions of star-branched polycondensates

Abstract

Of late much attention has been paid to star-branched polymers, being a good reference model for branched polymers, in general. Usually, monodisperse or narrow disperse polymers are analysed. Knowledge of molecular mass distributions is a key factor in the analysis and study of these systems. Star-branched polycondensates can be synthesised by reaction of a difunctional (AB) monomer with a compound RA r . Weight and number molecular mass distributions of star-branched polycondensates have been studied in relation to the initial molar ratio between R and the AB monomer (a), the average molecular mass per arm (β) and the number of arms (f). Simple probability density functions can be derived at, if molecules are split into -R (without core R) and +R (with core R). This enables further the representation in molecular mass units next to the representation in monomer units. Proper choice of α, β and f can either give nartower or broader distributions compared to the most probable distribution, which is the theoretical distribution for the pure AB polymer (a = 0). The resulting polymer might either have a uni-modal or a bi-modal molecular mass distribution.