Systematic Modification of the Glass Transition Temperature of Ion-Pair Comonomer Based Polyelectrolytes and Ionomers by Copolymerization with a Chemically Similar Cationic Monomer
Ion-pair comonomers (IPCs) where both the anion and cation contain polymerizable functional groups offer a route to prepare polyampholyte, ion-containing polymers. Polymerizing vinyl functional groups by free-radical polymerization produces bridging ion-pairs that act as non-covalent crosslinks betw...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-04-01
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| Series: | Gels |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2310-2861/7/2/45 |
| Summary: | Ion-pair comonomers (IPCs) where both the anion and cation contain polymerizable functional groups offer a route to prepare polyampholyte, ion-containing polymers. Polymerizing vinyl functional groups by free-radical polymerization produces bridging ion-pairs that act as non-covalent crosslinks between backbone segments. In particular the homopolymerization of the IPC vinyl benzyl tri<i>-n-</i>octylphosphonium styrene sulfonate produces a stiff, glassy polymer with a glass transition temperature (<i>T<sub>g</sub></i>) of 191 °C, while copolymerization with a non-ionic acrylate produces microphase separates ionomers with ion-rich and ion-poor domains. This work investigates the tuning of the <i>T<sub>g</sub></i> of the polyelectrolyte or ion-rich domains of the ionomers by copolymerizing with vinyl benzyl tri<i>-n-</i>octylphosphonium <i>p-</i>toluene sulfonic acid. This chemically similar repeat unit with pendant rather than bridging ion-pairs lowers the <i>T<sub>g</sub></i> compared to the polyelectrolyte or ionomer containing only the IPC segments. Rheological measurements were used to characterize the thermomechanical behavior and <i>T<sub>g</sub></i> of different copolymers. The <i>T<sub>g</sub></i> variation in the polyelectrolyte vs. weight fraction IPC could be fit with either the Gordon–Taylor or Couchman–Karasz equation. Copolymerization of IPC with a chemically similar cationic monomer offers a viable route to systematically vary the <i>T<sub>g</sub></i> of the resulting polymers useful for tailoring the material properties in applications such as elastomers or shape memory polymers. |
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| ISSN: | 2310-2861 |