Predictive design of polymer molecular weight distributions in anionic polymerization. Issue 2 (26th June 2019)

• Record Type: Journal Article
• Authors: Domanskyi, Sergii; Gentekos, Dillon T.; Privman, Vladimir; Fors, Brett P.
• Is Part Of: Polymer chemistry. Volume 11:Issue 2(2020)
• Page Start: 326
• Page End: 336
• Publication Date: 2019-06-26
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/c9py00074g
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : Polymer molecular weight distributions are targeted through kinetic modeled with high fidelity based on the temporal control of chain initiation in anionic polymerizations. 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 k p, 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.