Mechanically-induced redox processes offer a promising alternative to more conventional thermal and photochemical synthetic methods. For macromolecule synthesis, current methods utilize sensitive transition metal additives and suffer from background reactivity....

The sustainable synthesis of macromolecules with control over sequence and molar mass remains a challenge in polymer chemistry. By coupling mechanochemistry and electron‐transfer processes (i.e., mechanoredox catalysis), an energy‐conscious controlled radical polymerization methodology is realized. This work explores an efficient mechanoredox reversible addition‐fragmentation chain transfer (RAFT) polymerization process using mechanical stimuli by implementing piezoelectric barium titanate and a diaryliodonium initiator with minimal solvent usage. This mechanoredox RAFT process demonstrates exquisite control over poly(meth)acrylate dispersity and chain length while also showcasing an alternative to the solution‐state synthesis of semifluorinated polymers that typically utilize exotic solvents and/or reagents. This chemistry will find utility in the sustainable development of materials across the energy, biomedical, and engineering communities.

The diffusion coefficients of hydrogen were determined for three beta titanium alloys, which differ in the stability of the beta phase, and, for comparison, for one near-alpha titanium alloy in the temperature range from 40 ЊC to 500 ЊC. For this purpose, a step hydrogen concentration profile was produced by charging one side of rods of these materials with hydrogen by means of an electrochemical technique. After subsequent diffusion annealing, the hydrogen concentration profiles were determined analyzing small discs cut from these rods. The corresponding diffusion coefficient was calculated by adapting its value in such a way that a numerical diffusion simulation yields the experimentally determined profile. In all cases studied, the hydrogen diffusion coefficient was found to be independent of the hydrogen concentration and showed an Arrhenius-type temperature dependence. Hydrogen diffusion in alpha titanium was slower as compared to the beta titanium alloys under investigation. Furthermore, the diffusion coefficient of the metastable beta titianium alloys is only slightly affected by the prior heat treatment that determines the morphology and volume fraction of the precipitated alpha phase.

Carbon-based materials—such as graphene nanoribbons, fullerenes, and carbon nanotubes—elicit significant excitement due to their wide-ranging properties and many possible applications. However, the lack of methods for precise synthesis, functionalization, and assembly of complex carbon materials has hindered efforts to define structure–property relationships and develop new carbon materials with unique properties. To overcome this challenge, we employed a combination of bottom-up organic synthesis and controlled polymer synthesis. We designed norbornene-functionalized cycloparaphenylenes (CPPs), a family of macrocycles that map onto armchair carbon nanotubes of varying diameters. Through ring-opening metathesis polymerization, we accessed homopolymers as well as block and statistical copolymers constructed from “carbon nanohoops” with a high degree of structural control. These soluble, sp 2 -carbon-dense polymers exhibit tunable fluorescence emission and supramolecular responses based on composition and sequence. This work represents an important advance toward bridging the gap between small molecules and functional carbon-based materials.

A high sensitive detection method allows the direct determination of Pt2+/Pt4+ within a concentration range of ng/l (pptj. The procedure was used to establish the development of soluble platinum species during constant or dynamic polarisation of platinum electrodes in phosphate buffered saline solution.Platinum showed some properties of a passive metal. In the passivated state the dissolution was influenced by a surface film. Furthermore a soluble platinum species was found to be produced during the reduction of the surface oxide. These results confirmed by direct evidence the conclusions of earlier investigations concerning the corrosion of platinum based on electrochemical measurements.Eine hochernpfindliche Analysenmethode ermoglicht die direkte Bestimmung von Pt2+/Pt4+ bis in den Konzentrationsbereich von ng/l (pptj. Mit dem Verfahren wurde die Entstehung liislicher Platinspezies beim konstanten und dynamischen Polarisieren von Platinelektroden in phosphatgepufferter Kochsalzlosung nachgewiesen.Platin zeigte Eigenschaften eines passivierbaren Metalles. In passiviertem Zustand wurde das In-Losung-gehen des Metalles durch einen Oberflachenfilm minimiert. Desweiteren entstand eine Iosliche Platinspezies im Verlauf der Reduktion des Oherflachenoxides. Die Ergebnisse bestatigten die aufgrund elektrochemischer Messungen getroffenen Schlusse zur Platinkorrosion friiherer Untersuchungen mit direktem Nachweis.

A thermogravimetric method has been applied to study the hydrogen uptake in a metastable β‐titanium alloy. The tests were performed in H2‐Ar gas mixtures with various partial pressures of H2at temperatures between 482°C and 650°C. The results obtained were compared and supplemented by means of additional volumetric tests in hydrogen at low (absolute) pressure. Basic findings like decreasing solubility of hydrogen with increasing temperature could be verified and first information on the effect of surface conditions were gained. Thus it could be shown that despite the low atomic mass of hydrogen, thermogravimetry is an appropriate tool for the investigation of the hydrogen/metal interaction of titanium alloys.

The sustainable synthesis of macromolecules with control over sequence and molar mass remains a challenge in polymer chemistry. By coupling mechanochemistry and electron-transfer processes (i.e., mechanoredox catalysis), an energy-conscious controlled radical polymerization methodology is realized. This work explores an efficient mechanoredox reversible addition-fragmentation chain transfer (RAFT) polymerization process using mechanical stimuli by implementing piezoelectric barium titanate and a diaryliodonium initiator with minimal solvent usage. This mechanoredox RAFT process demonstrates exquisite control over poly(meth)acrylate dispersity and chain length while also showcasing an alternative to the solution-state synthesis of semifluorinated polymers that typically utilize exotic solvents and/or reagents. This chemistry will find utility in the sustainable development of materials across the energy, biomedical, and engineering communities.

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