Investigation of the influence of the nanocrystal (NC) surface chemistry on the (opto)electronic properties of NCbased thin films is of paramount importance for their further application in various devices. In this work, macroscopic superlattices of copper selenide (Cu 2−x Se) NCs in the form of thin films were prepared by self-assembly at the liquid/air interface accompanied by simultaneous ligand exchange with the inorganic S 2− as well as organic 1,2-ethanedithiol, 1,4-butanedithiol, 1,6hexanedithiol, and 1,8-octanedithiol ligands. By using X-ray photoelectron spectroscopy and optical absorption spectroscopy, we revealed that the newly introduced ligands largely replaced the native surfactants on the Cu 2−x Se NC surface and acted as crosslinkers between neighboring particles. Transport measurements, specifically focusing on the interparticle distance, indicated 5− 9 orders of magnitude increase in electrical conductance with decreasing the size of the ligands from octanedithiol to inorganic sulfide ions, suggesting that the newly introduced species provide efficient and controllable electronic coupling for adjacent Cu 2−x Se NCs. Finally, the NC arrays were employed as chemiresistors to show the potential of these macroscopic superlattices in sensing applications.

Thin films of cellulose ferulate were designed to study the formation of dehydrogenation polymers (DHPs) on anchor groups of the surface. Trimethylsilyl (TMS) cellulose ferulate with degree of substitution values of 0.35 (ferulate) and 2.53 (TMS) was synthesized by sophisticated polysaccharide chemistry applying the Mitsunobu reaction. The biopolymer derivative was spin-coated into thin films to yield ferulate moieties on a smooth cellulose surface. Dehydrogenative polymerization of coniferyl alcohol was performed in a Quartz crystal microbalance with a dissipation monitoring device in the presence of H 2 O 2 and adsorbed horseradish peroxidase. The amount of DHP formed on the surface was found to be independent of the base layer thickness from 14 to 75 nm. Pyrolysis-GC-MS measurements of the DHP revealed β-O-4 and β-5 linkages. Mimicking lignification of plant cell walls on highly defined model films enables reproducible investigations of structure−property relationships.