Fibre-reinforced epoxy composites are well established in regard to load-bearing applications in the aerospace, automotive and wind power industries, owing to their light weight and high durability. These composites are based on thermoset resins embedding glass or carbon fibres(1). In lieu of viable recycling strategies, end-of-use composite-based structures such as wind turbine blades are commonly landfilled(1-4). Because of the negative environmental impact of plastic waste(5,6), the need for circular economies of plastics has become more pressing(7,8). However, recycling thermoset plastics is no trivial matter(1-4). Here we report a transition-metal-catalysed protocol for recovery of the polymer building block bisphenol A and intact fibres from epoxy composites. A Ru-catalysed, dehydrogenation/bond, cleavage/reduction cascade disconnects the C(alkyl)-O bonds of the most common linkages of the polymer. We showcase the application of this methodology to relevant unmodified amine-cured epoxy resins as well as commercial composites, including the shell of a wind turbine blade. Our results demonstrate that chemical recycling approaches for thermoset epoxy resins and composites are achievable.

The biomineralization of bone remains a puzzle. During Haversian remodeling in the dense human cortical bone, osteoclasts excavate a tunnel that is then filled in by osteoblasts with layers of bone of varying fibril orientations, resulting in a lamellar motif. Such bone represents an excellent possibility to increase our understanding of bone as a material as well as bone biomineralization by studying spatio/temporal variations in the biomineral across an osteon. To this end, fluorescence computed tomography and diffraction scattering computed tomography with sub-micrometer resolution is applied to obtain position resolved fluorescence spectra and diffraction patterns in a 3D volume. The microstructural properties of the apatite biomineral are not homogeneous but depend critically on the time point at which it was laid down. This indicates that the nature of bone biomineral is highly dependent on the microenvironment during bone formation and remodeling.

Nature produces a multitude of composite materials with intricate architectures that in many instances far exceed the performance of their modern engineering analogs. Despite significant investigations into structure‐function relationships of complex biological materials, there is typically a lack of critical information regarding the specific functional roles of many of their components. To help resolve this issue, the authors present here a framework for investigating biological design principles that combines parametric modeling, multi‐material 3D printing, and direct mechanical testing to efficiently examine very large parameter spaces of biological design. Using the brick and mortar‐like architecture of mollusk nacre as a model system, the authors show that this approach can be used to effectively examine the structural complexity of biological materials and harvest design principles not previously accessible.

Advanced functional materials often contain multiple phases which are (nano) crystalline and/or amorphous. The spatial distribution of these phases and their properties, including nanocrystallite size and shape, often drives material function yet is difficult to obtain with current experimental techniques. This article describes the use of diffraction scattering computed tomography, which maps wide-angle scattering information onto sample space, to address this challenge. The wide-angle scattering signal contains information on both (nano) crystalline and amorphous phases. Rietveld refinement of reconstructed diffraction patterns is employed to determine anisotropic nanocrystal shapes. The background signal from refinements is used to identify contributing amorphous phases through multivariate curve resolution. Thus it is demonstrated that reciprocal space analysis in combination with diffraction scattering computed tomography is a very powerful tool for the complete analysis of complex multiphase materials such as energy devices.

Underwater attachment is a significant challenge, for which we have no good general solutions in our technology. Yet, a number of biological organisms have evolved solutions to this problem. One intriguing approach to underwater attachment is that of the marine bivalve mussel Anomia simplex that uses a biomineralized byssus to permanently anchor itself to substrates. The byssus has a highly complex hierarchical structure and contains over 90 wt% CaCO3. The byssus features a complex set of porosities, presumed to be highly important for the function of the attachment system. The pore space is the main focus of the present work. We characterize the three dimensional distribution of pore spaces in the byssus using micro-computed tomography (µCT) through a combination of in house mCT and high resolution synchrotron µCT. The pore structures are observed to fall into distinct categories in various parts of the byssus. We discuss the branching of one set of pores that reach the byssus substrate interface in particular. They form a network reaching the byssus surface that we now visualize in three dimensions.

The growth. and nucleation of biominerals are directed and affected by associated, biological molecules. In this' paper, we investigate the influence of occluded biomolecules on biogenic !,calcite from the coccolithophorid Pleurochtysis carterae and from chalk, a rock composed predominantly of fossil coccoliths. We compare the results with data on chalk from the extensively studied mussel Pinna nobilis :that served as a control. Using high resolution synchrotron powder X-ray diffraction combined with in situ heating, the influence of organic compounds on the structure of the inorganic phase was probed. Two heating cycles allow us to differentiate the effects,of thermal agitation and organic molecules. Single peak analysis and Rietveld refinement were combined to show significant differences resulting from the occluded biomolecules on the mineral phase in biogenic calcite in the mollusk shell and the coccolithophorids. These differences were reflected in lattice deformation (macrostrain), structure (microstrain), and atomic disorder distributions (delta(organic)). The influence of the biological macromolecules on the inorganic phase was consistently smaller in the P. carterae compared to P. nobilis. This suggests that the interaction between biomolecules and calcite is not as tight in the coccoliths as in the shell. Although the shape of chalk has been preserved over millions of years, no major influence on the crystal lattice was observed in the chalk samples.

Modern advanced diffraction experiments such as in situ diffraction, position-resolved diffraction or diffraction tomography generate extremely large data sets with hundreds to many thousands of diffractograms. Analyzing such data sets by Rietveld refinement is hampered by the logistics of running the Rietveld refinement program, extracting and analyzing the results, and possibly re-refining the data set based on an analysis of the preceding cycle of refinements. The complexity of the analysis may prevent some researchers either from performing the experiments or from conducting an exhaustive analysis of collected data. To this end, a MATLAB framework, MultiRef, which facilitates automated refinements, data extraction and intelligent choice of refinement model based on user choices, has been developed The use of MultiRef is illustrated on data sets from diffraction tomography, position-resolved diffraction and in situ powder diffraction investigations of crystallization.

Biological materials are complex and their investigation demands advanced characterization tools capable of elucidating their structure in three dimensions without the need for complicated sample preparation. Herein, we discuss our implementation of diffraction/scattering computed tomography (DSCT). DSCT is based on the use of diffraction information for tomographic reconstructions rather than linear attenuation as in regular μ-CT. This provides much additional information on the material under investigation. We illustrate the use of DSCT by discussion of data on a biomineralized attachment organ from a marine mussel. DSCT allowed mapping the spatial distribution of calcium carbonate polymorphs aragonite and calcite even though they were indistinguishable in absorption tomography. Detailed analysis of reconstructed diffraction patterns may provide additional insights as exemplified in the present case by mapping of the degree of chemical substitution in calcite.