3 research outputs found
Molecular Orientation at the Near-Surface of Photoaligned Films Determined by NEXAFS
Because
of the potential for use in display applications, photoalignment using
photosensitive materials has received considerable attention. Herein,
the influence of film thickness on thermally stimulated photoinduced
molecular reorientation structures of photoreactive liquid crystalline
polymer films at the near-surface and in bulk is investigated using
near-edge X-ray absorption fine structure (NEXAFS) and polarization
UV absorption spectroscopies, respectively. In films less than 90-nm
thick, the uniaxial in-plane orientation order in bulk gradually decreases.
In contrast, films thicker than 40 nm show a sufficient molecular
orientation at the near-surface. The three-dimensional orientation
structures are investigated using obliquely reoriented films fabricated
by slantwise <i>p</i>-polarized UV light exposure. Films
thicker than 40 nm display an effective slantwise orientation in bulk,
but the slantwise angle at the near-surface is much smaller than that
in bulk. Both the substrate–film interface and film thickness
play important roles in the reorientation behavior not only in bulk
but also at the near-surface of the photoalignment film