polyelectrolyte
Noun: A polyelectrolyte is a type of polymer (a large molecule composed of repeating subunits) that possesses multiple ionizable groups along its chain. When dissolved in a solvent like water, these groups dissociate, giving the polymer chain a net positive or negative electrical charge. This charged nature gives polyelectrolytes unique properties distinct from uncharged polymers.
Polyelectrolytes are classified based on the type of charge they carry when ionized. * Cationic polyelectrolytes have positively charged groups (e.g., from ammonium ions). * Anionic polyelectrolytes have negatively charged groups (e.g., from carboxylate or sulfate ions). * Ampholytic polyelectrolytes (or polyampholytes) contain both positive and negative groups.
The term is used to describe the substance's chemical nature and its functional behavior in solution.
- Many natural biological molecules are polyelectrolytes, such as DNA (which is an anionic polyelectrolyte due to its phosphate backbone) and proteins (which can be cationic, anionic, or ampholytic depending on pH).
- The flocculant added to clarify the water was a synthetic polyelectrolyte.
- The viscosity of the solution increased dramatically upon adding the polyelectrolyte because the charged polymer chains repelled each other and expanded.
- Polyelectrolyte Complexes (PECs) or Coacervates: These form when oppositely charged polyelectrolytes are mixed in solution. They attract each other and can form solid complexes or liquid-rich phases, which are useful in drug delivery and microencapsulation.
- Polyelectrolyte Multilayers (PEMs): These are thin films fabricated by alternately depositing layers of cationic and anionic polyelectrolytes onto a surface, a technique known as layer-by-layer (LbL) assembly.
- Polyelectrolytic (adjective): Relating to or characteristic of a polyelectrolyte.
- Polyion: Another term for the charged polymer chain of a polyelectrolyte.
- Polymer: The broader category to which polyelectrolytes belong.
- Electrolyte: A substance that produces ions when dissolved, a category that includes both simple salts (like NaCl) and polyelectrolytes.
- Ionic polymer
- Charged polymer
- Counterion: The small, oppositely charged ions (e.g., Na⁺, Cl⁻) that are released when a polyelectrolyte dissociates and that surround the polymer chain in solution.
- Charge Density: A critical parameter for polyelectrolytes, referring to the number of charged groups per unit length of the polymer chain.
- Flocculation: A common industrial application where polyelectrolytes are used to clump fine particles together so they can be more easily removed from water.
- an electrolyte of high molecular weight