Enhancement in crystallinity of poly(3-hexylthiophene) thin films prepared by low-temperature drop casting

Low-temperature casting of high molecular weight (HMW > 40 kDa) regioregular poly(3-hexylthiophene) (P3HT) is demonstrated to yield highly crystalline P3HT thin films with well defined and preferentially edge-on oriented [(100) contact plane] nanocrystallites on the pure and silanized Si/SiO₂ substrates. Transmission electron microscopy and X-ray diffraction provide evidence for the increase in preferential edge-on orientation of P3HT-conjugated backbone while decreasing the film preparation temperature below room temperature. The optimum growth temperature is about −12°C for the given concentration (2 mg/mL in CHCl₃). The reduced evaporation rate of the solvent results in a better selection of the thermodynamically stable orientation of nanocrystallites onto the substrate. The degree of preferential orientation and size of the crystallites can be further increased on n-octadecyltrichlorosilane-treated SiO₂ substrates as well as by annealing the films at 200°C for 1 h. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Eumelanin for nature‐inspired UV‐absorption enhancement of plastics

In the human body, the black‐brown biopigment eumelanin blocks harmful ultraviolet (UV) radiation. In the plastics industry, additives are often added to polymers to increase their UV‐absorption properties. We herein report an assessment of the biopigment eumelanin as a nature‐inspired additive for plastics to enhance their UV absorption. Since eumelanin is produced by natural sources and is nontoxic, it is an interesting candidate in the field of sustainable plastic additives. In this work, the eumelanin‐containing films of commercial ethylene–vinyl acetate copolymer, a plastic used for packaging applications, were obtained by melt compounding and compression molding. The biopigment dispersion in the films was improved by means of the melanin free acid treatment. It was observed that eumelanin amounts as low as 0.8 wt% caused an increase of the UV absorption, up to one order of magnitude in the UVA range. We also evaluated the effect of eumelanin on the thermal stability and photostability of the films: the biopigment proved to be double‐edged, working both as UV‐absorption enhancer and photo‐prooxidant, as thermogravimetric analysis and infrared spectroscopy revealed. © 2019 Society of Chemical Industry     

Aufbau einer Versuchsanlage zur katalytischen Spaltung des 9,10‐Dihydroxystearinsäuremethylesters mit Luftsauerstoff

The development of new catalysts for the oxidation of chemical compounds with oxygen as cheap and environmentally oxidant is an important topic of the current research. Due to the risk of the formation of potentially explosive gas mixtures aerobic oxidation reactions have to be performed with consideration of the explosion prevention. A safety concept for aerobic oxidation reactions and the construction of an experimental plant is presented. The oxidative cleavage of methyl 9,10‐dihydroxystearate to azelaic acid methyl ester and pelargonic acid was investigated as a model reaction.     

Value creation for tenants in environmentally certified buildings

Previous research suggests that environmental certification (EC) affects rental rates in non-residential buildings, but there is still little understanding of how tenants differentiate such buildings from those without EC. This paper examines whether and how tenants perceive value creation in EC premises in Sweden. The findings (based on 29 questionnaire responses and 14 interviews with tenants in EC buildings) inform landlords and tenants on the development of EC strategies for improved organizational outcomes. EC creates value for tenants principally as support for their environmental management and reporting (e.g., low energy demand). EC is important for tenants internally, raising employee environmental awareness and improving employee attraction and retention. Tenants are generally positive about employee morale, indoor environmental quality (IEQ) and rental costs. However, it is not clear if such perceptions are dependent on features of modern premises in general, such as new fixtures, fittings and furnishings, and space-efficiency or from some EC-related feature. Tenants do not identify health or productivity increase in their EC premises. Findings suggest that the research focus should be shifted from investigating health and productivity increases through IEQ improvement to understanding the motivational improvement through value alignment with employees through EC.     

Atomistic modelling of the Fe-Cr-C system

For the purpose of modelling the impact of carbon on radiation damage phenomena in steels, we have performed an extensive set of first principle calculations on the Fe-Cr-C system. The calculated solution and diffusion enthalpies of carbon in iron and in chromium agree well with experimental data, as do the relative formation energies of mono-carbides, cementite, Hägg and M₂₃C₆ carbides. Our data further indicate that interstitial carbon is attracted to a solute iron atom in bcc chromium, while the reaction between carbon and a solute chromium atom in bcc iron is repulsive. An empirical potential fitted to data for iron carbides is capable of reproducing melting behaviour of cementite, while the predicted interaction with point defects agrees less well with DFT data than a potential recently published by Hepburn and Ackland.     

德国中小城镇在国土开发中扮演的重要角色

与大多数欧洲城市相比,德国的城镇体系属于均衡发展的典范。地区的高度自治、联邦体制以及强有力的州政府使德国在两千多年的城市发展历程中,逐渐形成了大中小城市遍布全国的空间形态。这些城市都具有相似的生活质量、便捷的交通和便利的服务。基于对中小城镇的概括定义,本文将首先简要介绍城市均衡发展的历史渊源及小城镇在德国的重要作用,并举例分析一些进行中的都市化过程,随后将选取纽伦堡城市区域作为中小城镇的成功案例重点介绍,最后简要说明支持城镇发展的联邦政策规划。