Phosphonium-Based Polyzwitterions: Influence of Ionic Structure and Association on Mechanical Properties

Philip J. Scott, Glenn A. Spiering, Yangyang Wang, Zach D. Seibers, Robert B. Moore, Rajeev Kumar, Bradley S. Lokitz, Timothy E. Long

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

This manuscript describes a synthetic strategy and structure-property investigation of unprecedented phosphonium-based zwitterionic homopolymers (polyzwitterions) and random copolymers (zwitterionomers). Free radical polymerization of 4-(diphenylphosphino)styrene (DPPS) provided neutral polymers containing reactive triarylphosphines. Quantitative postpolymerization alkylation of these pendant functionalities generated a library of polymers containing various concentrations of neutral phosphines, phosphonium ions, and phosphonium sulfobetaine zwitterions. The zwitterionic homo- and copolymers exhibited significantly higher glass transition temperatures (Tg) and enhanced mechanical reinforcement in comparison to neutral and phosphonium analogues. These changes in Tg and mechanical properties were attributed to nanoscale morphological domains, which formed due to electrostatic interactions between zwitterionic groups, as revealed by X-ray scattering and broadband dielectric spectroscopy (BDS). BDS revealed increased static dielectric constants (>25) for the phosphonium zwitterionomers compared to ionomeric or neutral analogues. These high static dielectric constants for the solvent-free polyzwitterions supported their stronger polarization response in comparison with polymers containing neutral phosphines and phosphonium ions, and these interactions accounted for morphological differences and enhanced mechanical behavior. This work describes a versatile strategy for modulating electrostatic interactions with tunable mechanical properties for an unprecedented family of zwitterionic polymers.

Original languageEnglish (US)
Pages (from-to)11009-11018
Number of pages10
JournalMacromolecules
Volume53
Issue number24
DOIs
StatePublished - Dec 22 2020
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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