Dresden 2020 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 50: Poster Session III

CPP 50.24: Poster

Tuesday, March 17, 2020, 14:00–16:00, P1C

Competing chain extension between exchange and irreversible reactions — •Michael Lang and Frank Böhme — Leibniz-Institut für Polymerforschung Dresden Hohe Straße 6, 01069 Dresden

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.