Interpretation of Molecular Structure and Kinetics in Melt Condensation of A₂ Oligomers, B₃ Monomers, and Monofunctional Reagents

Abstract

This article applies kinetic Monte Carlo simulations to interpret experimental measurements in the polymerization of hyperbranched poly(ether esters)s in a melt condensation of A2 oligomers and B3 monomers. Building on the analytical modeling of Flory and Stockmayer, additional effects of cycle formation, unequal reactivities, and end-capping reagents are added into the simulations to describe A2 + B3 polymerization in the absence of a solvent. The experimental data have been published separately, and here it is compared to the model predictions in order to quantitatively assess whether the data are consistent with these models. On the basis of the modeling, we conclude that cycle formation is negligible, suppression of the third B group is insignificant, and the mobility of the free B3 monomer leads to enhancement of its reaction rate. The addition of the monofunctional end-capping reagents does not necessarily lead to suppression of branching in the A2 + B3 system and depends sensitively on the stoichiometry of the reactants.

Influence of polymerization procedure on polymer topology and other structural properties in highly branched polymers obtained by A2+B3 approach

“…Our earlier simulation studies on the formation and properties of HB systems, where A 2 was slowly added onto B 3 (A 2 over B 3 ), have already been reported [15,17]. These results were in good agreement with experimental observations for polyurea and polyester type HB polymers.…”

“…Recently, we demonstrated the preparation of highly branched segmented polyurea copolymers by the slow addition of oligomeric A 2 onto B 3 [15,17]. As displayed in Table 1, calculations based on the branching coefficient suggest major differences in the critical A 2 and B 3 conversions at the gel point for three different polymerization methods.…”

“…A brief report was recently published by Fossum and Czupik on the influence of reaction procedure on various properties of aromatic poly(ether sulfones) obtained by the A 2 þ B 3 approach [16]. In our earlier publications [14,15,17] we reported the influence of the concentration of the reaction medium on the gel point, degree of branching and polymer properties for reactions where oligomeric A 2 was added slowly onto B 3 . In this study we report the results of our modeling studies on the influence of polymerization method and cyclization rate on the topology, degree of branching, number and weight average molecular weight, and polydispersity index of the polymers formed.…”

Synthesis and properties of a novel hyperbranched polyphosphoramidate using an A2 + CB2 approach

“…They are obtained in a single polymerization step and they possess many unique properties of dendrimers such as low viscosity, excellent solubility and a large quantity of terminal groups. Therefore there has been widespread interest in the design, synthesis and exploitation of the structure–property dependence of hyperbranched polymers, especially in the fields of biomedicine and nanotechnology.…”

The Ring-Forming Parameter For the Network Formation by DGEBA－POP diamine Polymerisation: Introduction of State of Reaction in Diamine Unit

“…[1] Further, the ring structure takes one of significant factors in the network; the relationship between the ring structure and delay of gel point has been taken as important research objects. [2,3] Rings(there are other names, such as loops, cyclisations) influence the viscoelastic behaviour because they do not contribute to elasticity but to concentration. [4,5] This study is intended to give some quantitative measure to the ring structure at the gel point.…”