Abstract: A polymer chain in which two ends are attached at an interface boundary physically or chemically is called as a polymer loop.Based on the normal random walk(NRW)in the simple cubic lattice,the available conformational number C₁₁⁽³⁾(N)of a model polymer loop with the chain length Ncan be obtained from the available conformational number of the corresponding polymer tail.It was shown that the number C₁₁^(N)≈6^N/2(6лN³)_1/2, where 6 Nis the conformational number of a free chain with the length N.The computer ""experiments"including the exact enumeration and the Monte Carlo simulation were used for the comparison with the theory.This result gives a formal reference frame to compare with the conformation of the more complicated model or the real polymer loop.

Key words: Polymer conformation, Loop chain, Random walk