Structural Principles

Abstract

The simplest form a macromolecule¹ can have is that of an unbranched chain. One speaks of a “chain-like” macromolecule or a “chain” molecule, because macromolecules consist of a large number of links, i.e., they have a chain structure. However, in a real chain the links are not held together in an identical manner from link to link. Furthermore the links can move within each other. It is therefore better to think of a pearl necklace in which the stiffness of the chain is determined by the type of pearls and the material used to string the pearls together. This does not exclude the fact that linear macromolecules in solution have a coiled-up structure similar to a randomly tangled ball of yarn or wire. Because of thermal motion these coils are constantly changing their form. The speed of these changes depends on the temperature. To what extent a macromolecule is stretched or coiled depends on the nature of the chain elements, the type of chain bonding, and the solvent.²