We present a simple method to calculate conformational entropy differences between different polymer structures from a thermostated molecular dynamics simulation. The mathematical concept is based on a special Monte Carlo quadrature approach combined with density estimation. First, this approach will be derived for a general integrant 𝑓. Then, we will apply the entropy estimator in order to investigate different protein resistant surfaces based on derivates of polyethylenglycol peg. For peg, the highest entropy value is found, which is an indicator for an optimal protein resistant function of peg. Such a preference is also seen in thermostated molecular dynamics simulations of larger chain lengths of peg.