In biophysics and colloidal chemistry, polymorphism is the ability of lipids to aggregate in a variety of ways, giving rise to structures of different shapes, known as "phases". This can be in the form of spheres of lipid molecules (micelles), pairs of layers that face one another (lamellar phase, observed in biological systems as a lipid bilayer), a tubular arrangement (hexagonal), or various cubic phases (Fd3m, Im3m, Ia3m, Pn3m, and Pm3m being those discovered so far). More complicated aggregations have also been observed, such as rhombohedral, tetragonal and orthorhombic phases.
It forms an important part of current academic research in the fields of membrane biophysics (polymorphism), biochemistry (biological impact) and organic chemistry (synthesis).
