Authors Lang, M. ; Böhme, F.
Title Competing Exchange and Irreversible Reactions in a Linear Co-Polycondensation Lead to a Broad Composition Window Where Tunable High Molecular Weight Polymers can be Prepared
Date 01.05.2019
Number 56022
Abstract A co-polycondensation reaction is discussed analytically and by Monte-Carlo simulations where two reactive units compete for reactions with an alternating third reactive unit, whereby irreversible reactions replace bonds which are able to undergo exchange reactions. The resulting number average molar mass, M-n, exhibits only one distinct peak at the stoichiometric condition of both competitors with the alternating partner. The weight average molar mass, M-w, reaches an additional second peak at the stoichiometric condition between the dominating competitor and the alternating partner. Both peaks of M-w surround a range of compositions where a rather high and approximately constant M-w is obtained. The degree of polymerization of the dominating and alternating reaction partners is rather insensitive towards composition fluctuations if the reaction mixture remains within this composition window. This promotes high molecular weight species and more homogeneous weight distributions at incomplete mixing conditions. An ideal reference case (identical reaction rates for all reactions) is solved analytically to describe these reactions. The position of the stable composition window and the average molar masses inside this window can be tuned by choosing appropriate precursor molecules, reaction mixtures, or post-tuning steps at later times.
Publisher Macromolecular Theory and Simulations
Citation Macromolecular Theory and Simulations 28 (2019) 1800069

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