**Reptation** is a specific (snake-like)

thermal motion of very long

linear macromolecules in the melts and concentrated solutions of polymers These systems called also entangled polymers are characterized with effective internal scale commonly known as

*‘the length of macromolecule between adjacent entanglements’* *M*_{e} . The

concept of

reptation was introduced into

polymer physics by Pierre-Gilles de Gennes

[De Gennes PG Reptation of a polymer chain in the presence offixed obstacles J. Chem Phys 55, 572 - 579 (1971)
] to explain the dependence of

mobility of

macromolecule on its length

The

linear macromolecules reptate if the length of

macromolecule *M* is bigger than ten times

*‘the length of macromolecule between adjacent entanglements’* *M*_{e} . There is no

reptation motion for polymers with

* M<10 M*_{e} so that the point 10

*M*_{e} is a point of dynamic

phase transition Due to the

reptation motion the

coefficient of self-diffusion and conformational relaxation times of macromolecules depend on the length of

macromolecule as

*M*^{-2} and

*M*^{3} correspondingly

[Pokrovskii VN A justification of the reptation-tube dynamics of a linear macromolecule in the mesoscopic approach Physica A 366 88-106 (2006)][Pokrovskii VN The reptation and diffusive modes of motion of linear macromolecules J. Exper Theor Phys 106 (3) 604-607 (2008)]The conditions of existence of

reptation in the

thermal motion of macromolecules of complex

architecture (macromolecules in the form of

branch star comb and others) has not established yet

## References