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- ItemConsolidation and performance gains in plasma-sintered printed nanoelectrodes(Cambridge : Royal Society of Chemistry, 2023) Engel, Lukas F.; González-García, Lola; Kraus, TobiasWe report on the unusual, advantageous ageing of flexible transparent electrodes (FTEs) that were self-assembled from oleylamine-capped gold nanospheres (AuNPs) by direct nanoimprinting of inks with different particle concentrations (cAu = 3 mg mL−1 to 30 mg mL−1). The resulting lines were less than 2.5 μm wide and consisted of disordered particle assemblies. Small-Angle X-ray Scattering confirmed that particle packing did not change with ink concentration. Plasma sintering converted the printed structures into lines with a thin, electrically conductive metal shell and a less conductive hybrid core. We studied the opto-electronic performance directly after plasma sintering and after fourteen days of storage at 22 °C and 55% rH in the dark. The mean optical transmittance T̄400-800 in the range from 400 nm to 800 nm increased by up to ≈ 3%, while the sheet resistance Rsh strongly decreased by up to ≈ 82% at all concentrations. We correlated the changes with morphological changes visible in scanning and transmission electron microscopy and identified two sequential ageing stages: (I) post-plasma relaxation effects in and consolidation of the shell, and (II) particle re-organization, de-mixing, coarsening, and densification of the core with plating of Au from the core onto the shell, followed by solid-state de-wetting (ink concentrations cAu < 15 mg mL−1) or stability (cAu ≥ 15 mg mL−1). The plating of Au from the hybrid core improved the FTEs' Figure of Merit FOM = T̄400-800·Rsh−1 by up to ≈ 5.8 times and explains the stable value of ≈ 3.3%·Ωsq−1 reached after 7 days of ageing at cAu = 30 mg mL−1
- ItemPolyacrylonitrile-containing amphiphilic block copolymers: self-assembly and porous membrane formation(Cambridge : RSC Publ., 2023) Gemmer, Lea; Niebuur, Bart-Jan; Dietz, Christian; Rauber, Daniel; Plank, Martina; Frieß, Florian V.; Presser, Volker; Stark, Robert W.; Kraus, Tobias; Gallei, MarkusThe development of hierarchically porous block copolymer (BCP) membranes via the application of the self-assembly and non-solvent induced phase separation (SNIPS) process is one important achievement in BCP science in the last decades. In this work, we present the synthesis of polyacrylonitrile-containing amphiphilic BCPs and their unique microphase separation capability, as well as their applicability for the SNIPS process leading to isoporous integral asymmetric membranes. Poly(styrene-co-acrylonitrile)-b-poly(2-hydroxyethyl methacrylate)s (PSAN-b-PHEMA) are synthesized via a two-step atom transfer radical polymerization (ATRP) procedure rendering PSAN copolymers and BCPs with overall molar masses of up to 82 kDa while maintaining low dispersity index values in the range of Đ = 1.13-1.25. The polymers are characterized using size-exclusion chromatography (SEC) and NMR spectroscopy. Self-assembly capabilities in the bulk state are examined using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) measurements. The fabrication of isoporous integral asymmetric membranes is investigated, and membranes are examined by scanning electron microscopy (SEM). The introduction of acrylonitrile moieties within the membrane matrix could improve the membranes’ mechanical properties, which was confirmed by nanomechanical analysis using atomic force microscopy (AFM).