Reptation

Reptation is the thermal motion of very long linear, entangled macromolecules in polymer melts or concentrated polymer solutions. Derrived from the word reptile, reptation suggests the movement of entangled polymer chains as being analogous to snakes slithering through one another.

Repton is a mobile point residing in the cells of a lattice, connected by bonds.

Entanglement means the topological restriction of molecular motion by other chains.

The concept of reptation was introduced into polymer physics in 1971 by Pierre-Gilles de Gennes to explain the dependence of the mobility of a macromolecule on its length. It is used as a mechanism to explain the viscous flow in an amorphous polymer. Sir Sam Edwards and Masao Doi later refined the theory.