Orientation of platelets in multilayered nanocomposite polymer films

The orientation of platelets in micro‐meter‐thick polymer‐clay nanocomposite films was investigated with small‐angle neutron scattering (SANS), small‐angle X‐ray scattering (SAXS), and wide‐angle X‐ray diffraction (WAXD). The films with various clay contents (15–60% by mass fraction) were prepared by a layer‐by‐layer approach from polymer‐clay solutions that led to the formation of a high degree of orientation in both polymer and clay platelets. Shear‐induced orientation of polymer‐clay solutions is compared with the orientation of polymer‐clay films. SANS, SAXS, and WAXD, with beam configurations in and perpendicular to the spread direction of the film, were used to determine the structure and orientation of platelets. In all films, the clay platelets oriented preferentially in the plane of the film. The observed differences in semidilute solutions, with clay surface normal parallel to the vorticity direction, versus bulk films and with clay surface normal parallel to the shear gradient direction at clay mass fractions of 40 and 60%, were attributed to the collapses of clay platelet during the drying process.