With charged groups located throughout their polymer chains, polyelectrolytes are an intriguing family of polymers with a wide range of industrial, scientific, and biological applications. These charged groups have special qualities include high solubility in water and the capacity to create complex structures through electrostatic interactions. They can also be positive (cationic) or negative (anionic).The capacity of polyelectrolytes to engage in powerful electrostatic interactions with counterions in solution is one of their most important properties. An ion cloud, or "cloud" of counterions, forms around the polymer chain when polyelectrolytes are in an aqueous environment due to the charged groups on the polymer backbone drawing in oppositely charged ions from the solution. The behavior of polyelectrolytes in solution is significantly influenced by this ion cloud. This ion cloud's existence influences a number of crucial polyelectrolyte characteristics. In comparison to non-charged polymers, it first causes a notable increase in the solution's osmotic pressure. The chemist Frederick G. Donnan, who explored this effect in the early 20th century, is credited with giving it its name, the Donnan effect. In biological systems like cells, where it affects functions like ion transport and cell volume management, the Donnan effect is very significant. Additionally, polyelectrolytes display a phenomena known as "polyelectrolyte complexation," in which electrostatic interactions between oppositely charged polyelectrolytes can result in the formation of complex structures. Hydrogels, micelles, and multilayer films are a few examples of materials with special qualities that might arise from this complexation. These substances are used in tissue engineering, drug delivery, and covering a variety of surfaces. Polyelectrolytes have numerous uses in materials research, but they are also crucial to biological systems. The genetic material of living things, such as DNA and RNA, is polyelectrolyte because of the negatively charged phosphate groups that run the length of their backbone. Gene expression and replication depend on the interactions between these polyelectrolytes and proteins. Gaining an insight of the behavior of polyelectrolytes is essential to utilizing their special qualities in a variety of applications. Scholars persistently investigate the potential uses of these intriguing charged polymers, spanning from sophisticated medication delivery systems to the treatment of wastewater, underscoring their adaptability and significance.
