Form Factors of Block Copolymer Micelles with Excluded-Volume Interactions of the Corona Chains Determined by Monte Carlo Simulations

The scattering of a diblock copolymer micelle has been simulated using Monte Carlo techniques. The scattering is analyzed using a novel model, where the corona is represented as a dilute/semidilute polymer solution with a radial profile. This approach decouples the scattering due to interaction and connectivity induced density fluctuations and scattering due to the radial profile of the corona. Three different profiles have been used to fit the simulated corona scattering: a box with a Gaussian tail and two maximum entropy (ME) profiles; chain penetration into the core region is not allowed for any of the profiles. Excellent fits are obtained, especially for a ME profile with three parameters. An excluded-volume parameter and the corona compressibility are obtained and show a strong dependence on surface coverage. The derived expressions for the form factor provides a new approach for analyzing experimental data obtained by neutron or X-ray small-angle scattering for block copolymer micelles with significant intra- and interchain excluded-volume interactions.