A group attached to the polymer backbone and present in the repeating unit is called a pendant group. Examples of pendant groups are the methyl group in polypropylene and the benzene ring in polystyrene.
Common Pendant Groups: (left) polypropylene and (right) polystyrene
Polymers with pendant groups still are designated as linear polymers. The presence of pendant groups modifies the properties of a polymer.
David Whisnant (Wofford College). Partial support for this work was provided by the National Science Foundation's Division of Undergraduate Education through grants DUE #9950809 and DUE #9950296. Additional support was provided by the Camille and Henry Dreyfus Foundation.