| Abstract: | Symmetrical diblock copolymers (P(S(D)‐b‐nBMA)) of deuterated poly(styrene) (PS(D)) and poly(nbutylmethacrylate) (PnBMA) were investigated by neutron reflectometry with respect to periodicity and interfacial width. Four different molecular weight P(S(D)‐b‐nBMA) samples were used to prepare thin films by spin coating on glass substrates. Two of the samples were in the intermediate segregated state. The other two samples were in the bulk disordered state, however, due to thin film geometry a surface and substrate induced ordering could be revealed. Utilizing the respective theories (Matsen and Bates for intermediate segregated samples and Fredrickson for a surface and substrate induced ordering), the product of interaction parameter χ and chain length N was calculated. Taking account for the different molecular weights, an interaction parameter was obtained which is the same for all of the four samples, within the experimental error. Using the strong segregation theory from Semenov to calculate χ for the intermediate segregated samples, the interaction parameters for the four samples are not consistent. |
