Association theory is a discredited theory first advanced by chemist Thomas Graham

Thomas Graham (chemist)

Thomas Graham FRS was a nineteenth-century Scottish chemist who is best-remembered today for his pioneering work in dialysis and the diffusion of gases.- Life and work :...

 in 1861 to describe the molecular structure of substances such as cellulose

Cellulose

Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....

 and starch

Starch

Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...

, now understood to be polymer

Polymer

A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

s. Association theory postulates that such materials are composed of a collection of smaller molecules bound together by an unknown force. Graham termed these materials colloids. Prior to the development of macromolecular

Macromolecule

A macromolecule is a very large molecule commonly created by some form of polymerization. In biochemistry, the term is applied to the four conventional biopolymers , as well as non-polymeric molecules with large molecular mass such as macrocycles...

 theory by Hermann Staudinger

Hermann Staudinger

- External links :* Staudinger's * Staudinger's Nobel Lecture *....

in the 1920s, association theory remained the most prevalent model of polymer structure in the scientific community.