Due to the high abundance of copper on the earth and its high intrinsic electrical conductivity, copper nanowires (CuNWs) represent a promising material for transparent electrodes. In this work, an environmentally friendly and scalable synthesis that requires a low process temperature is studied. The optimum temperature is found at 79 °C, which results in nanowires with the lowest diameters. The as‐synthesized solution is sprayed to transparent conducting films, which are in turn subjected to various post‐treatments such as thermal sintering or washing with propionic acid to enhance their electro‐optical performance. Following both the optimum protocol for the synthesis and post‐treatment, a sheet resistance of 10.3 Ω ◻−1 at a transparency of 83.4% is achieved. Moreover, the CuNW‐films are tested as transparent heaters and show a homogeneous heat distribution. For the electrical properties of the films, a temperature dependence of resistance that is lowered around 28% compared to the one for bulk copper is found.

Terpolymerization reactions with a mixed-monomer feedstock of epoxides, CO2, and β-butyrolactone (BBL) at two different CO2 pressures are presented. The Lewis acidic zinc complex BDICF3–Zn–N­(SiMe3)2 1 is able to catalyze both the ring-opening polymerization (ROP) of BBL and the ring-opening copolymerization of epoxides and CO2. The carbon dioxide concentration thereby displays an attractive tool for the chemoselective tailoring of the incorporation of both monomer types to either a block or a statistical configuration. A high CO2 pressure (40 bar) leads to a block structure, whereas 3 bar CO2 allows the two catalytic cycles, ROP of BBL and ring-opening copolymerization of cyclohexene oxide and CO2, to proceed with similar rates. This results in a statistical polymerization behavior. Reducing the CO2 pressure from 40 to 3 bar involves a change in the reaction order of CO2 from zero- to first-order dependency. The statistical polymerization pathway offers a promising route to terpolymers with one mixed-glass transition temperature that can be adjusted in a range between 5 and 115 °C. Terpolymers in block structure show two segregated glass transitions. This phase separation was also confirmed via atomic force microscopy. Referring to the mechanical behavior of the resulting terpolymers, a decrease of the Young modulus for both the block and the statistical structure compared to the very brittle poly­(cyclohexene carbonate) is observed due to the incorporation of soft poly­(3-hydroxybutyrate) (PHB). An enhanced elongation at break is revealed for the block structure when the molecular weights exceed 100 kg/mol. The biobased monomer limonene oxide is also successfully terpolymerized with CO2 and BBL. Interestingly, the block structure shows a tunable stress–strain behavior depending on the amount of PHB in the terpolymer.

decisive drawbacks are (i) only a low to moderate level of scalability, (ii) restrictions for the size as well as the material of the substrate due to high-vacuum processes at elevated temperatures, iii) a lack of mechanical flexibility and iv) optical transparency.A few of these obstacles have been overcome with the emergence of novel materials such as carbon nanotubes (CNTs), graphene, [2] graphene oxide, [3] poly (3,4ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), [4] metal nanomeshes, [5] silver-coated polyester films (AgHT), [6] silver flakes, [7] silver nanoparticles, [8] copper oxide nanoparticles [9] as well as metal nanowires. [10,11] For the majority of these materials, scalable and high-yield synthesis protocols or fabrication techniques exist and these materials can potentially be deposited at almost arbitrary scale and under ambient conditions. Due to the cost-effectiveness, the ease-of-processing and the scalability, deposition methods such as inkjet printing, [12] direct laser writing, [13] spray coating [14] or screen printing [15] have become increasingly popular over the last years and raised academic and industrial interest.A high optical transparency of the deposited films is already a requirement for numerous antenna applications including solar cells, [16] sun shields on satellites, [17] radio-identification tags (RFIDs), [18][19][20][21] smart glasses, [22] bandstop filters to reduce the interference from wireless local area networks (WLANs) [23] as well as for energy harvesting. [24,25] Due to this broad application spectrum and the commercialization potential, notable technology companies including the so-called Big Techs, have recently filed several patents related to transparent conductive films and their use for antennas. [26][27][28] The conducting and transparent films presented in this work were made of a commercially available silver nanowire (AgNW)-based screen print paste. The use of screen printed AgNWs for antennas has already been reported in 2014 by Song et al. [29] However, in that work, the antenna films were fully opaque, which is a criterion for exclusion in many applications. In this work, as transparent electrode (TE) material, AgNWs were selected since this material is currently considered as the most promising alternative to the prevailing TE material, i.e., indium tin oxide (ITO), [30] with regard to the electro-optical performance as well as the chemical and the mechanical stability. [31] The antennas presented in this work show a highThe advent of mobile communication has made antennas omnipresent. Conventional methods of antenna manufacturing cannot address the growing demands for novel applications requiring transparent and flexible antennas. In this paper, transparent silver nanowire films are studied with respect to their highfrequency properties. Transparent silver nanowire (AgNW)-based antennas that are screen printed onto flexible polyethylene terephthalate (PET) substrate are reported. Transparent films with a low sheet resistance of 8.5 Ω sq −...

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Copper nanowires (CuNWs) have increasingly become subjected to academic and industrial research, which is attributed to their good performance as a transparent electrode (TE) material that competes with the one of indium tin oxide (ITO). Recently, an environmentally friendly and aqueous synthesis of CuNWs was demonstrated, without the use of hydrazine that is known for its unfavorable properties. In this work, we extend the current knowledge for the aqueous synthesis of CuNWs by studying their up-scaling potential. This potential is an important aspect for the commercialization and further development of CuNW-based devices. Due to the scalability and homogeneity of the deposition process, spray coating was selected to produce films with a low sheet resistance of 7.6 Ω/sq. and an optical transmittance of 77%, at a wavelength of 550 nm. Further, we present a comprehensive investigation of the degradation of CuNWs when subjected to different environmental stresses such as the exposure to ambient air, elevated temperatures, high electrical currents, moisture or ultraviolet (UV) light. For the oxidation process, a model is derived to describe the dependence of the breakdown time with the temperature and the initial resistance. Finally, polymer coatings made of polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA), as well as oxide coatings composed of electron beam evaporated silicon dioxide (SiO2) and aluminum oxide (Al2O3) are tested to hinder the oxidation of the CuNW films under current flow.