What is a polyelectrolyte solution?
Polyelectrolytes are polymers whose repeating units bear an electrolyte group. Polycations and polyanions are polyelectrolytes. These groups dissociate in aqueous solutions (water), making the polymers charged. Like salts, their solutions are electrically conductive. Like polymers, their solutions are often viscous.
What is a polyelectrolyte multilayer?
Layer-by-layer (LbL) assembly of polyelectrolytes (PEs) is a method for preparing highly tunable thin film polymer coatings. Such coatings or films are denoted henceforth as polyelectrolyte multilayers (PEMs).
What are Polycations?
Medical Definition of polycation : a molecule or chemical complex having positive charges at several sites.
What is the difference between cationic and anionic polyelectrolyte?
A polyelectrolyte is characterized by its molecular weight, the nature of the functional group, and the charge density. Sensitivity to pH occurs with cationic polymers in which quaternary ammonium groups are dominant, and with anionic polymers containing sulfonic acid groups.
What is polyelectrolyte effect?
Early in the 1940s Fuoss [5] defined a phenomenon called “polyelectrolyte effect”, i.e. reduced viscosity of polyelectrolyte solutions increases as the solution is diluted, which is totally different from that of neutral polymers.
Why are peptides polyelectrolytes?
Polyelectrolytes (PEs) are molecules that bear multiple negative or positive charges. PE-based delivery systems, such as polyelectrolyte complexes (PECs), PE-coated nanocarriers, and PE multilayers, were designed to protect peptides and proteins from degradation and facilitate their absorption.
How many types of polyelectrolyte are there?
Polyelectrolytes are ionizable polymers that change their polymeric conformations upon their environmental changes. They are of two types: strong and weak polyelectrolytes. Strong polyelectrolytes are charged over a wide pH range.
What is anionic polyelectrolyte?
Polyelectrolytes are water-soluble polymers that have natural or synthetic sources. Anionic polyelectrolytes can be of various types. Among the various anionic polymers, the acrylamide- based polymers are the most common types, depending on their applications.
What is polyelectrolyte flocculation?
Polyelectrolyte flocculants are polymers that are either branched or linear, but carrying ionic charge along their chain. They are accordingly classified as cationic, anionic or non-ionic polymers. These flocculants neutralise surface charges on cells and bind particles together by physical or chemical forces.
Are Peptides polyelectrolytes?
Polymers that incorporate both acidic and basic groups are defined as polyampholytes, and the most common representatives of these are peptides and proteins.
What kind of charges does a polyelectrolyte have?
Some important synthetic polyelectrolytes are listed in Table 2. Polyelectrolytes may conveniently be classified as anionic, cationic or ampholytic, according to whether the ionized polymer carries negative charges, positive charges or both.
What makes a polyelectrolyte a weak or strong Pel?
Polyelectrolytes (PELs) are polymers that carry charges within their backbone or in side chains. Usually, discrimination is made between weak and strong PELs. Weak PELs are polymers with weakly acidic or basic groups, which are protonated or deprotonated depending on the pH of the surrounding medium, resulting in a pH-dependent charge density.
How are polyelectrolytes classified as cationic or ampholytic?
Polyelectrolytes may conveniently be classified as anionic, cationic or ampholytic, according to whether the ionized polymer carries negative charges, positive charges or both. A number of books, 1–4 book chapters 5–8 and reviews 9–11 have appeared which discuss various aspects of polyelectrolyte behaviour.
How are polyelectrolytes used in everyday life?
Polyelectrolytes show many applications in fields, such as in water treatment as flocculation agents, in ceramic slurries as dispersant agents, and in concrete mixtures as super-plasticizers. Furthermore, many shampoos, soaps, and cosmetics contain polyelectrolytes.