A new approach for patterning epiclon-based polyimide precursor films using a lyotropic liquid crystal template

Blends of hydroxypropyl cellulose (HPC) in lyotropic phase have been prepared with a new epiclon-based poly(amic acid) (PAA) in different ratios. The detailed surface morphology of the PAA/HPC films was examined by polarized light microscopy (PLM) and atomic force microscopy (AFM). Besides the specific interactions, such as the hydrogen bonds between PAA and the liquid crystalline component, a slight cross-linking produced in the PAA structure by UV irradiation stabilized the resulting morphology. The effect of UV exposure and the influence of the HPC component weight ratio on the morphology developed by the PAA/HPC blends were investigated. The band texture, typical for lyotropic HPC solutions, evidencing different intensities and dimensions, is observed from atomic force microscopy images in PAA/HPC, being distinguished even at high PAA content and is also maintained after HPC removal with a selective solvent, namely acetone. These results lie at the basis of future investigations concerning high performance mixed alignment layers used in display devices or cell culture substrates with tuned morphology.