Dynamic Monte Carlo simulations are performed for polymer chains confined between two parallel plates.The configurational entropy S of the polymer chain is calculated by using the scanning method

and the influence of the distance D between the two parallel plates and chain length n on the entropy is studied.The dependence of entropy reduction (S0-S) on D verifies the scaling results of de Gennes.Moreover

our results give the regime of the scaling results.When D is very small

the polymer chains are confined markedly

and S0-S is proportional to the polymer chain length.The latter indicates that the average repulsive force of the two plates exerting on one segment tends to be independent of the chain length.With the increase of D

the influence of the two parallel plates on the entropy becomes weaker and weaker

and the average repulsive force exerting on one segment increases with the chain length.At large D

the influence of the plates on the entropy can be ignored

and the configurational entropy becomes the same as that in the free space.