What is the Difference Between Ionomers and Polyelectrolytes?

Ionomers and polyelectrolytes are two types of polymer materials that differ in their ionic content and structure. The key difference between ionomers and polyelectrolytes is:

• Ionomers: These are polymers containing both electrically neutral and ionized groups. They are copolymers, and a small amount of ionized groups are attached to the backbone of the polymer material via covalent bonds. Ionomers have a low ion content and are generally soluble in solvents of low dielectric constant. Some ionomers, such as poly(ethylene-co-methacrylic acid), have ionic attractions that strongly influence their properties, allowing them to act similarly to crosslinked polymers or block copolymers.
• Polyelectrolytes: These are polymers containing electrolytic groups, with more than 80% of the groups being electrolytic. Polyelectrolytes are generally polymers with a high ion content soluble in solvents of a high dielectric constant. They are used in various applications, including semi-permeable membranes and ion exchange processes.

In summary:

• Ionomers have a mix of neutral and ionized groups, with a low ion content.
• Polyelectrolytes have electrolytic groups, with more than 80% of the groups being electrolytic.
• Ionomers are generally soluble in solvents of low dielectric constant.
• Polyelectrolytes are generally soluble in solvents of high dielectric constant.

Comparative Table: Ionomers vs Polyelectrolytes

The main difference between ionomers and polyelectrolytes is the proportion of ionized groups in their structures. Here is a table summarizing the differences between the two:

Ionomers are copolymers containing both nonionic repeat units and a small amount of ionized groups, typically less than 15%. They can act like crosslinked polymers or block copolymers, but they are not crosslinked and are instead a type of thermoplastic called a reversible crosslinker.

Polyelectrolytes, on the other hand, have a higher proportion of ionized groups and are used in various applications, such as membranes and catalyst binders in electrochemical energy conversion and storage technologies. Anion exchange polyelectrolytes (AEPs) are an example of polyelectrolytes, which have been systematically reviewed and studied for their development and importance in cationic species and polymer backbone.