The application of polymer materials is significantly influenced by their crystallization behaviors.Up to now

it is hard to study the crystallization behavior of polymer on the molecular level

because of the large molecular weight

wide molecular weight distribution and many kinds of mesophases.Normal alkanes

with the same linear hydrocarbon chain structure as polymer

are ideal model systems for polymers and have attracted more attention on their confined crystallization behaviors.There are three kinds of confinement systems for n-alkanes crystallization

which are one-dimensional-confinement film

two-dimensional-confinement mesopores or nanochannels and soft three-dimensional-confinement microemulsions

respectively.The crystallization behaviors and phase transitions of n-alkanes confined in media behave differently from their bulk counterparts

which can be attributed to the confinement effect on nucleation and phase transitions.This article reviews the crystallization behaviors and phase transitions of n-alkanes in three kinds of confinement systems

and also makes a brief overview on polymer confined crystallization behaviors in the same systems

trying to illustrate that n-alkane is the excellent model for the study of complex confined crystallization behaviors of polymers

especially for polyethylene.