Issue 2, 2020

Predictive design of polymer molecular weight distributions in anionic polymerization

Abstract

Molecular weight distributions (MWD) have a substantial impact on a diverse set of polymer physical and rheological properties, from processability and stiffness to many aspects of block copolymer microphase behavior. The precise MWD compositions of these polymers can be modularly controlled through temporal initiation in anionic polymerizations by metered addition of a discrete initiating species. With the technique described in this work, we identify initiator addition profiles through theoretical modeling which can be used to prepare any desired arbitrary MWD. This kinetic model reproduces experimental MWDs with high fidelity. Our modeling strategy incorporates a detailed kinetic description of polymer initiation and propagation, including the association and dissociation equilibria of the living polymer chain ends. We simplify the kinetic model by incorporating the aggregation phenomena into an effective propagation rate constant kp, allowing it to vary with the polymer chain length (i). Importantly, this model also yields the ability to predict MWDs at any arbitrary value of monomer conversion during the polymerization. Lastly, we simulate MWDs for a variety of new, yet unmeasured, initiator addition profiles, demonstrating the predictability of this approach.

Graphical abstract: Predictive design of polymer molecular weight distributions in anionic polymerization

Supplementary files

Article information

Article type
Paper
Submitted
16 jan 2019
Accepted
12 jún 2019
First published
13 jún 2019

Polym. Chem., 2020,11, 326-336

Author version available

Predictive design of polymer molecular weight distributions in anionic polymerization

S. Domanskyi, D. T. Gentekos, V. Privman and B. P. Fors, Polym. Chem., 2020, 11, 326 DOI: 10.1039/C9PY00074G

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