1.1 Motivation
Polymers are ubiquitous in our day-to-day life in the form of plastics, resins,
adhesives, rubber, cellulose, and so on. Some of these like natural resins and rubber
have been in use for centuries. Biopolymers like proteins and nucleic acids play
crucial roles in biological processes. A polymer molecule or macromolecule is a species
of high molecular weight composed of several repeating structural units connected
by covalent bonds. These structural units represent residues from small molecular
compounds called “monomers” which are employed in the preparation of the polymer.
For example, a common plastic material polyethylene (PE) is produced by reacting
(or “polymerizing” ) ethylene molecules to form chain-like macromolecules consisting
of thousands of ethylene residues. The structural units can be connected in any
conceivable pattern leading to linear or branched polymers. The presence of branching
results in a number of polymer chain architectures such as star, comb or cascade
polymers. These molecular topologies are sought after, because they impart desired
macroscopic properties to the polymeric material. For example, short chain branches
on linear low density polyethylene (LLDPE) confer great flexibility to the resulting
material, thus making it suitable for manufacturing plastic bags and sheets.
Another broad classification of polymers depends upon their internal chemical
composition. Polymers derived from a single type of monomers are referred to as
homopolymers, while others produced by linking two or more types of chemically
distinct monomers are designated as copolymers. One common example of copolymer