Soft matter physics is a subfield of condensed matter physics that deals with materials that are soft, deformable, and often exhibit complex behavior. These materials are typically composed of organic molecules, such as polymers, surfactants, and biological macromolecules, which interact with each other through weak forces, such as van der Waals, electrostatic, and hydrophobic interactions.

* 2.1 Onsager's variational principle and Onsager–Machlup. * 2.2 Direct variational methods for approximation solutions. RSC Publishing

Several experimental techniques are used to study soft matter materials: