Polymers are large molecules that are made up of smaller units called monomers. A copolymer is made up of two or more monomers. Polyampholytes are a group of polymers that contain both positively and negatively charged monomers within the same chain. Proteins containing amino acid residues with both acidic and basic functional groups are an example of polyampholytes. A polyampholyte widely used in the food and pharmaceutical industry is gelatin. Polyampholytes may be either neutral (possess equal number of positive and negative charges) or have an overall charge of one sign.

The behavior of polyampholytes in solution is controlled by either attractive or repulsive interactions between the positively and negatively charged groups. If the overall charge is very large, the electrostatic forces between monomers become repulsive, and in a dilute solution, the polymer extends and adopts a necklace-like conformation. A polyampholyte with an equal number of positively and negatively charged groups collapses due to attractive forces within the same polymer chain. At a particular pH value, called the isoelectric point, the overall charge on a polyampholyte will be zero.

Synthetic polymers have molecules with one or more repeating structures and a range of chain lengths. The goal of this research was to prepare water-soluble polyampholytes from copolymers comprised of three neutral monomers, by a controlled method of polymerization, followed by modification of the polymer end groups. The overall compositions of the copolymers tend to approach the compositions of the initial monomer mixtures, indicating that the copolymers have a homogeneous composition.

The long term goal of this project is to prepare a family of polyampholytes with varying amounts of positively and negatively charged groups that are water-soluble at room temperature, with homogeneous compositions, a narrow distribution of chain lengths, and molecular weights large enough for the purpose of determining the solution properties of these materials in dilute aqueous media.