Polymer crystallization

together with glass transition and rheology

is one of the problems which have not been eventually solved in polymer science.Because the properties of polymeric materials are strongly dependent on the crystallization behavior and morphology

polymer crystallization is the most fundamental problem of polymer physics.Comparing with the crystallization of small molecules

the conformational entropy plays a critical role in polymer crystallization due to its linear structure.This leads to complex behaviors of polymer crystallization and the controversies on both the understanding of phenomena and the establishment of the polymer theory.Recently

as the accumulation of the new phenomena from the experiments and computational simulation and the advances in theoretical methods

it is the right time to reveal the nature of polymer crystallization in theory.In present review

from point view of the difference of crystallization in polymer and small molecule systems

the classic theory

new phenomena from both experiments and computational simulation of polymer crystallization and the development and difficulties of theories focusing on these new phenomena were reviewed.