The lamellar period in symmetric diblock copolymer thin films studied by neutron reflectivity and AFM

The lamellar structure of a symmetric diblock copolymer was studied as a fu nction of temperature. We used dPEP-PDMS with a molecular weight of 8.3 kg/ mol as model system. The polymer was dissolved in chloroform and spin-caste d on silicon wafers into thin uniform films. The degree and direction of la mellar ordering in the thin films was measured by small angle neutron scatt ering. Neutron reflectivity was used to measure the detailed lamellar struc ture in the thin films. For the temperature scans only the first order Brag g peak was measured to determine the lamellar period in the film. Our exper imental results are compared to theoretical predictions on the scaling beha vior of the lamella period as a function of temperature. The morphology of the surface was investigated by atomic force microscopy. Holes were found a round defects in the films. The cross-section of the holes revealed the lam ellar structure with a periodicity comparable to what was found by neutron reflectivity. (C) 1999 Elsevier Science B.V. All rights reserved.