From evaporation-induced self-assembly to shear-induced alignmentElectronic supplementary information (ESI) available: Evolution of the ZnO nanorod aspect ratio (AR) with synthesis time. Supplementary information on SAXS measurements. SEM image of EISA at high volume fractions. Microscopy images of thin films processed with low and high AR ZnO nanorods by EISA. Domain-like alignment by EISA. Supplementary information on rheology measurements. See DOI: 10.1039/c6nr06586d

• Main Authors: Srikantharajah, R, Schindler, T, Landwehr, I, Romeis, S, Unruh, T, Peukert, W
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c6nr06586d

The functionality of compact nanostructured thin films depends critically on the degree of order and hence on the underlying ordering mechanisms during film formation. For dip coating of rigid nanorods the counteracting mechanisms, evaporation-induced self-assembly (EISA) and shear-induced alignment (SIA) have recently been identified as competing ordering mechanisms. Here, we show how to achieve highly ordered and homogeneous thin films by controlling EISA and SIA in dip coating. Therefore we identify the influences of the process parameters including temperature, initial volume fraction and nanorod aspect ratio on evaporation-induced convective flow and externally applied shear forces and evaluate the resulting films. The impact of evaporation and shear can be distinguished by analysing film thickness, surface order and bulk order by careful in situ SAXS, Raman and SEM-based image analysis. For the first time we derive processing guidelines for the controlled application of EISA and SIA towards highly ordered thin nematic films. The impact of evaporation-induced convective flows and externally applied shear forces by dip coating is distinguished for different process conditions by in situ SAXS, Raman and SEM-based image analysis.