Prediction of intrinsic viscosities of mixed hyperbranched–linear polymers

Abstract

Using an extension of a previously developed methodology, the intrinsic viscosity of mixed hyperbranched–linear polymers is calculated as a function of molecular weight, relative reactivity of the functional groups on the brancher AB₂-molecules and the amount of linear AB-comonomer used. It is shown that using even relatively high amounts of linear AB-comonomers does not increase the intrinsic viscosity too much. For a ratio 4:1 of linear to brancher monomers the intrinsic viscosity only increases by a factor of 2 compared to a hyperbranched polymer originating from brancher AB₂ monomers only. The intrinsic viscosity of hyperbranched (co)polymers as a function of degree of branching follows a master curve not depending on how the polymer (using AB₂ or AB-monomers) was formed. This relation only fails at very high and very low degrees of branching where the architecture of the polymer chains becomes a very important factor.

Some considerations are made concerning the question of how predictions of the intrinsic viscosity can be extended to predictions of the viscosity at high concentration or in the melt. The possible use of the polymer–reference interaction site model (PRISM) and dissipative particle dynamics is discussed.