Bidispersity Improves the Toughness and Impact Resistance of Star-Polymer Thin Films

Utku Gürel, Sinan Keten, Andrea Giuntoli*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Branched polymer architectures are used to tune the mechanical properties of impact-resistant thin films through parameters, such as chain length and grafting density. While chain dispersity affects molecular properties, such as interpenetration and entanglements, structure-property relationships accounting for dispersity are challenging to obtain experimentally and are often neglected in computational models. We employ molecular dynamics simulations to model the high-rate tensile elongation and nanoballistic impact of thin films composed of bidisperse star polymers with varying arm lengths. We find that, at fixed molecular weight, high dispersity can significantly enhance the toughness and impact resistance of the films without decreasing their elastic modulus. Bidisperse stars with fewer longer arms are less entangled, but stretch and interpenetrate for longer times during crazing, leading to increased toughness. These findings highlight controlled dispersity as a design strategy to improve the mechanical properties of polymer composites across Pareto fronts.

Original languageEnglish
Pages (from-to)302-307
Number of pages6
JournalAcs Macro Letters
Volume13
DOIs
Publication statusPublished - 19-Feb-2024

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