Dissemination of IT for the Promotion of Materials Science (DoITPoMS)

DoITPoMS Teaching & Learning Packages The Glass Transition in Polymers Conformation
The Glass Transition in Polymers AimsIntroductionTheory 1Theory 2 - kinetics vs thermodynamicsMeasurement of TgDemonstrationsSummaryQuestionsGoing further
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Conformation

The conformation of a polymer molecule is the arrangement of the bond orientations, both within the backbone, and any side-groups and branches. There are three specific orientations, called trans, +gauche and -gauche, as represented in the Newman projections below. The conformation can be changed by rotation about single bonds.

Diagram of trans conformation Diagram of + gauche conformation Diagram of - gauche conformation

Trans

+ Gauche

- Gauche

The angle of rotation away from the trans-conformation is called the torsion angle, f, and the free energy of the bond in question can be plotted as a function of this angle.

Graph of potential against torsion angle

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