The persistent presence of endocrine-disruptive chemicals (EDCs) in surface waters has raised serious environmental and health concerns, necessitating the development of efficient and sustainable water treatment strategies. Advanced oxidation using visible light-driven photoactive bismuth oxyiodide nanoparticles is an emerging technique for efficient water treatment. The effects of reaction parameters such as pH and temperature on the formation of semiconductor BixOyIz nanoparticles remain underemphasized despite their critical role in tailoring size, morphology, elemental composition, specific surface area, and photocatalytic activity. Accordingly, this study aimed to develop a modified solvo-hydrothermal method to optimize the synthesis of BixOyIz nanoparticles under varying pH and temperature conditions, and to establish correlations between their physicochemical properties - characterized by XRD, SEM, EDX, TEM, FTIR, UV-vis DRS, XPS, PL, Raman, and BET - and their photocatalytic performance. The results revealed that the sensitivity of iodine to pH and temperature significantly influenced particle growth and specific surface area, while the overall photocatalytic activity was also determined by the various phases of bismuth oxides and hydroxides formed during synthesis. It was demonstrated that the particles synthesized at pH values between 1.5 and 5.5 showed the highest photocatalytic activity due to the combined effect of larger surface area and interstitial surface defects formed due to hydroxylation. Finally, the possible configuration mechanism of the synthesized nanoparticles and the kinetics of photocatalytic degradation were discussed.

AbstractStudies have increasingly aimed at improving the piezoresistive behavior of polymer‐based conductive composites (CPCs) for strain‐sensing, with inorganic nanomaterial enhancement offering research opportunities. This study investigates the impact of incorporating zinc sulfide nanospheres (ZnS NSs, 1–7 wt.%), synthesized via a one‐step hydrothermal method, into a poly(vinylidene fluoride) (PVDF) polymer matrix together with multi‐walled carbon nanotubes (MWCNTs). Field emission scanning electron microscopy (FE‐SEM), energy‐dispersive X‐ray spectroscopy (EDX), and X‐ray diffraction (XRD) analyses reveal that ZnS NSs comprise a mixture of ZnS0.96O0.04 and S phases. While of ZnS NSs minimally impact tensile properties of the PVDF/MWCNT composites, they reduce elongation at break at 5 wt.%. During 15‐cycle strain sensing up to 3% strain, ZnS NSs‐enhanced composites outperformed PVDF/1 wt.% MWCNT. The reference sample's resistance change ratio (ΔR/R0) decreased below 1% with increased cycles, while 1 wt.% ZnS NSs increased ΔR/R0 to 3%, reducing changes upon cycle increments. Higher ZnS NSs levels (3–7 wt.%) resulted in ΔR/R0 exceeding 4–5%, indicating enhanced strain sensing performance. Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) showed limited impact of ZnS NSs on the thermal properties and microstructure of the composites.

Electron beam (EB) modification was carried out on the polylactide (PLA) fibers at the temperature both below and above the glass transition temperature (Tg) under nitrogen atmosphere. The irradiation at elevated temperature was performed by using a novel fiber stretching frame setup to protect fibers from shrinking, in which a permanent constant tension was loaded along fiber bundles to maintain their straightness throughout the irradiation. In contrast to irradiation at room temperature, where PLA predominantly undergoes chain scission, irradiation above Tg can introduce long chain branching (LCB) into the PLA matrix without the need of branching additives. The polymer chain orientation in the amorphous regions of drawn fibers is beneficial for achieving a higher yield of LCB. This improvement is attributed to the shortened intermolecular distance and the disentanglement in the amorphous domains which are caused by melt spinning and post-drawing. This is counteracted by the typically high crystallinity degrees in PLA fibers (measured by differential scanning calorimetry, 31.0 % - 41.2 % for neat fibers), due to the chain scission is mainly induced by EB in the rigid crystalline domains. The chain scission effect in the crystalline regions mitigates the branching effect in the amorphous regions on the material properties, such as tensile strength, even in irradiation above Tg. However, by reducing the PLA fiber crystallinity while applying temperatures above Tg, the amount of EB-induced LCB molecules was significantly increased. Moreover, the branched unit per PLA chain increases when a dose of 50 kGy is applied, as determined by analyzing the branching ratio g' using multi-detector size exclusion chromatography. In addition, the amount of branched unit also increases with the increasing irradiation dose. The tensile properties of fibers with varying drawing ratios were analyzed before and after irradiation. The resulting tensile properties are primarily determined by the draw ratio and appear to be barely affected by crystal orientation (examined using synchrotron Xray scattering). However, the crystal orientation increases with higher irradiation doses (above Tg) and is likely driven by the interplay between chain scission and cold crystallization.

Dipeptides can be self-assembled via non-covalent bonds towards functional nanostructures for diverse applications in nanotechnology. Here, we introduce a convenient microfluidics-guided dipeptide design as a platform for photodegradation of contaminants in water. Titanium dioxide (TiO2) nanoparticles (NPs) are chosen as photocatalysts due to their vastly studied properties. By using a well-defined microchannel architecture, the dipeptide N-fluorenylmethoxycarbonyl diphenylalanine (Fmoc-FF) and TiO2 NPs are efficiently mixed leading to a self-assembled Fmoc-FF hydrogel with embedded TiO2. Owing to shear-thinning and rapid self-healing of Fmoc-FF hydrogels, we can transfer and inject Fmoc-FF/TiO2 hydrogels into any other microdevice for specific applications, where these low-molecular-weight-gelator- (LMWG-)based Fmoc-FF hydrogels fill out the microchannel volume. Different morphologies of Fmoc-FF/TiO2 hydrogels are obtained by simple concentration screening of TiO2 NPs and Fmoc-FF. Owing to the density of the three-dimensionally twined Fmoc-FF nanofibers, solutions swelling the dipeptide hydrogel can be exchanged without leaching out TiO2 NPs. By further analysis, our hydrogel-filled flow cell can be employed for continuous-flow photodegradation in water under light irradiation. Especially, compared to the TiO2 NPs suspension, Fmoc-FF/TiO2 hydrogels with relatively low concentrations of TiO2 exhibit enhanced photodegradation capabilities due to better dispersion of nanoparticles. Such strategy provides a versatile platform for embedment of small inorganic catalysts or enzymes for (bio-)chemical conversion of solutes passing through the hydrogel network.

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Cross-linked polylactides (PLAs) were produced by electron beam (EB) irradiation at 80 degrees C using different preset crystallinities (0 to 13.3%), without using cross-linking-promoting additives. Based on functional group conversion detected by Fourier-transform infrared spectroscopy, molecular build-up mechanisms based on a two-stage chain recombination (from geometric T-type to H-type branching) were proposed for EB-induced cross-linking in additive-free PLA. Furthermore, EB-induced PLA crystallization has been discussed based on the combined evidence from morphology, crystallinity, and crystallization behaviors identified by polarized-light optical microscopy, X-ray diffraction, and differential scanning calorimeter (DSC). Several interpretations of the thermal property of EB-induced cross-linked PLA were presented from the point of view of chain scission and cross-linking in a coexisted system. The high irradiation dose obviously shifted the melting temperature (T-m) and cold crystallization temperature (T-cc) of irradiated PLA to a lower region than those of neat PLA. Moreover, the different preset crystallinities of the PLA starting materials did not lead to an obvious difference among irradiated PLAs with respect to T-g, T-m, T-cc, and cross-link density, according to DSC and equilibrium swelling measurements.

Abstract The interest in bio‐based alternatives to classical polyesters such as poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) is steadily growing to achieve a more sustainable approach to polymer materials. In this study, PBT/poly(butylene furanoate) (PBF) blends are prepared, characterized and extrusion foamed. PBF as a bio‐based polyester offers two advantages. The ecological footprint of the material is reduced, and additionally, it can be used in Diels‐Alder reactions at the blend surface to support fusion of the foamed beads. The blending behavior of the polyesters is investigated using samples prepared in a microcompounder, particularly focused on the miscibility of the blends and transesterification reactions. The blends are thermodynamically immiscible but show a certain degree of transesterification according to nuclear magnetic resonance (NMR) spectroscopy. The morphology of blend beads produced by an extrusion foaming process is analyzed regarding their cell density, cell size distribution, and open‐cell content. It is shown that PBF has a positive effect on the bead foam morphology. The use of a bifunctional linker designed for chemical fusion of the bead surfaces allows to obtaining of molded parts, in contrast to beads containing pure PBT.

The superlattice in a quantum dot (QD) film on a flexible substrate deformed by uniaxial strain shows a phase transition in unit cell symmetry. With increasing uniaxial strain, the QD superlattice unit cell changes from tetragonal to cubic to tetragonal phase as measured with in situ grazing-incidence small-angle X-ray scattering (GISAXS). The respective changes in the optoelectronic coupling are probed with photoluminescence (PL) measurements. The PL emission intensity follows the phase transition due to the resulting changing inter-dot distances. The changes in PL intensity accompany a redshift in the emission spectrum, which agrees with the Förster resonance energy transfer (FRET) theory. The results are essential for a fundamental understanding of the impact of strain on the performance of flexible devices based on QD films, such as wearable electronics and next-generation solar cells on flexible substrates.

A series of hybrid organic–inorganic perovskites, based on naphthalene ammonium cations have been investigated. All materials exhibit edge- or face-sharing 1D chain structures and broadband light emission arising from the self-trapped excitons.

Polylactic acid (PLA) is one of the most promising bioplastic representatives that finds application in many different areas, e.g., as single-use products in the packaging industry, in the form of mulch film for agriculture, or in medical devices. For the development of new areas, especially in terms of long-term applications and the production of recyclable products, the material properties controlled by processing must be known. The state of the art is investigations at the global scale (integral values) without consideration of local structure inhomogeneities and their influence on the material properties. In this work, morphological, thermal, and mechanical properties of injection-molded PLA tensile bars are investigated at different length scales (global and local) as a function of processing parameters. In addition to the processing parameters, such as melt temperature, mold temperature, and cooling time in the mold, the influence of the D-isomer content on the crystallization behavior and the resulting material properties are investigated. The material was found to form crystalline structures only when cooled in a mold tempered above Tg. In addition, PLA with a lower content of D-isomer was found to have a higher degree of crystallinity. Since the mechanical properties obtained by tensile tests could not be correlated with the degree of crystallinity, detailed analysis were performed showing a characteristic inhomogeneous morphology within the tensile bars. By means of micromechanical investigations on samples with different microstructure ranges, the relationship between local morphology and failure behavior could be explained.

When applying electron or gamma irradiation to poly-3-hydroxybutyrate (P3HB), main chain scissions are the dominant material reactions. Though propositions have been made that crosslinking in the amorphous phase of P3HB occurs under irradiation, a conclusive method to achieve controlled additive free irradiation crosslinking has not been shown and no mechanism has been derived to the best of our knowledge. By applying irradiation in a molten state at 195 °C and doses above 200 kGy, we were able to initiate crosslink reactions and achieved gel formation of up to 16%. The gel dose Dgel was determined to be 200 kGy and a range of the G values, the number of scissions and crosslinks for 100 eV energy deposition, is given. Rheology measurements, as well as size exclusion chromatography (SEC), showed indications for branching at doses from 100 to 250 kGy. Thermal analysis showed the development of a bimodal peak with a decrease in the peak melt temperature and an increase in peak width. In combination with an increase in the thermal degradation temperature for a dose of 200 kGy compared to 100 kGy, thermal analysis also showed phenomena attributed to branching and crosslinking.

Additive-free biodegradable polylactides (PLAs) with different crystallinities from 0 to 13.3% (according to x-ray diffraction, XRD) were used as starting materials modified by the electron beam (EB) with several irradiation doses at 25 °C (below glass transition temperature, Tg) in nitrogen. The crystallinity effects on radical decay and molecular structure transformation were investigated. After irradiation, the main stable radical remained in PLA is –O–C*(CH3)–CO–. During irradiation, radical reactions were inhibited by high crystallinity. Large amounts of EB-induced crosslinking and long-chain branching (LCB) were introduced by performing irradiation at 80 °C. An increasing crystallinity has been found that restrained crosslinking and LCB due to the poor chain mobility in the crystalline areas. An increase of crystallinity from 0 to 13.3% obviously decreased the saturated crosslink content from 65% to 43% and restrained LCB formation. This study also verified that strict moisture control combined with applying an irradiation temperature above Tg can be a universal method to introduce large amounts of crosslinking and LCB in different grades of additive-free PLA.

The effect of electron induced reactive processing (EIReP) on the properties of biodegradable polylactide/ masticated polycaprolactone (PLA/PCL) blends was firstly investigated without introducing any chemical additives. Subsequently, the melt spinnability of EIReP modified PLA/PCL blends was explored by a piston spinning. Different PCL concentrations (0, 5 and 10 wt%), applied dose (0, 12.5 and 25 kGy) and take up speeds (500 and 2000 m min (1)) were evaluated in order to investigate their influences on the fiber morphology, thermal and mechanical properties. SEM investigation indicated that the non-irradiated PLA/PCL fibers demonstrated less uniform diameter. However, the EIReP modification leads to a homogenous fiber diameter distribution hence uniform as-spun fibers can be produced. The crystallinity of PLA phase increased concomitantly with increased PCL contents for all fibers, whereas it slightly reduced by increasing dose. In addition, the crystallinity degree of neat PLA raised from 6.19 to 36.05% by increasing take up speed from 500 to 2000 m min(-1). Interestingly, the irradiated PLA/PCL blend fibers with 5 and 10 wt% PCL demonstrated an increased fracture strain of 48.7 and 34.4%, respectively, compared with their non-irradiated fibers. It can be due to the enhanced chain entanglements and interfacial bonding between two phases. However, the irradiated fibers demonstrated similar initial modulus and reduced tenacity compared with the non-irradiated fibers.

Injection-molding of rather slow crystallizing poly (L-lactic acid) (PLLA) was analyzed regarding the formation of crystal nuclei at different distances from the skin in a standard test bar. The relative number of nuclei in the various regions of fully amorphous test bars was estimated by evaluation of the kinetics of cold-crystallization, being faster in the skin than in the core region of the component. Simulation of the cooling-rate- and shear-rateprofiles along the cross-section of the molded bar suggests that the different nuclei numbers in skin and core mainly are caused by the higher shear rate in surface-near regions, though being supercritical for shear-induced nuclei formation also in the core. The latter conclusion is derived by comparing both the cold-crystallization kinetics and semicrystalline morphology with those of non-injection molded PLLA. The simulated shear-rate data, after conversion into specific-work-of-flow data, were found significantly exceeding the critical specific work of flow for shear-induced nuclei formation, being around 25 kPa, in all regions of the component. The results of the present study successfully demonstrate that knowledge about the crystallization kinetics of the sheared and quiescent melt of PLLA can be used to predict structure formation in industrial processing.

Two recently developed experimental devices for investigating soft matter deformation are presented. Both devices exploit the capabilities of a modern synchrotron beamline to enable advanced and highly precise materials-science experiments in which X-ray scattering is registered. The devices can be operated both in monotonic as well as cyclic mode and are implemented into a beamline at DESY , Hamburg (Germany). Hence, relevant experimental parameters, such as displacement, force and temperature, are recorded synchronously with the individual X-ray scattering patterns. In addition, spatial variation of materials deformation can be monitored and recorded with optical microscopy. This unique sample environment enables in situ X-ray experiments in transmission, i.e. small- or wide-angle X-ray scattering (SAXS or WAXS), and in grazing-incidence geometry, i.e. grazing-incidence (GI-) SAXS or WAXS. One device with stepper motors is designed for studies of slow, (quasi-) static deformation and the other one with pneumatic actuators can be used for fast, impact deformation. Both devices are available to external beamline users, too.

This work reports on an environmentally friendly method to produce encapsulated phase change material with a thin nickel coating, applicable for heat conversion, storage and thermal management of heat-sensitive components and suitable for active heating by electromagnetic radiation. A critical issue for the metallization is the adhesion between the polymer capsule shell and the metal layer. Based on previous studies using the bio-molecule dopamine as adhesion promoter in composites and for plastics metallization, commercial paraffin microcapsules were coated with an ultrathin polydopamine film via a simple wet chemical process. Subsequently, a thin, uniform and compact nickel layer was produced by electroless metallization. The successful deposition of both layers was verified with a broad range of imaging and spectroscopic techniques. For the first time, surface-enhanced IR spectroscopy was used to study the deposition of ultrathin PDA films. The combination of SEM and energy-dispersive X-ray spectroscopy allowed resolving the spatial distribution of the elements Ni, N, and O in the MC shell. Electrically conducting paths in the Ni shell were verified by conductive AFM. Thermal analysis revealed that the coated microcapsules show a phase change enthalpy of approx. 170 J/g, suitable for thermal storage and management. Additionally, the nickel layer enhanced the thermal diffusivity of the microcapsule powders and enables a fast heating of the PCM microcapsules by microwave radiation, demonstrating the applicability of the metallized MCs for controlled heating applications. Graphical abstract

The purity and safety of water as a finite resource is highly important in order to meet current and future human needs. To address this issue, the usage of environmentally friendly and biodegradable adsorbers and flocculants is essential. Chitosan, as a biopolymer, features tremendous properties as an adsorber and flocculant for water treatment. For the application of chitosan as an adsorber under acidic aqueous conditions, such as acid mine drainage, chitosan has been modified with hydrophobic hexanoyl chloride (H-chitosan) to reduce the solubility at a lower pH. In order to investigate the influence of the substitution of the hexanoyl chloride on the adsorption properties of chitosan, two chitosans of different molecular weights and of three different functionalization degrees were analyzed for the adsorption of CdSO4(aq) and Al2(SO4)3(aq). Among biobased adsorbents, H-chitosan derived from the shorter Chitosan exhibited extraordinarily high maximum adsorption capacities of 1.74 mmol/g and 2.06 mmol/g for Cd2+ and sulfate, and 1.76 mmol/g and 2.60 mmol/g for Al3+ and sulfate, respectively.

Poly(butylene terephthalate) (PBT) is difficult to foam due to its unfavorable rheological behavior (low melt strength, no strain hardening). In particular, a high expansion and a homogeneous cell morphology are difficult to achieve. This can be altered successfully by addition of multifunctional chain extenders. Chain extenders cause nondefined and rarely understood changes in the polymer architecture usually described as branching. In this contribution, the synthesis of two series of PBT copolyesters with defined short-chain branched units is presented. Dilinoleic derivatives with linear C-9 and C-7 alkyl side chains are employed to reflect short-chain branches and are incorporated into PBT in various molar ratios. Characterization by NMR spectroscopy and size exclusion chromatography demonstrates the random chain structure and high molar masses of the terpolyesters. Incorporation of dilinoleic derivatives results in the reduction of PBT crystallinity, decreased glass transition temperatures, and altered rheological behavior, in particular of extensional rheology characterized by strain hardening. The comparison to control copolyesters without branches proves that strain hardening is caused by the branches. A higher concentration of branches induces stronger strain hardening, resulting in successful foaming. It is demonstrated that the new terpolyesters have properties comparable with PBT treated with chain extenders.

Polymer/mosquito-repellent scaffolds exhibit increasing importance in long-lasting human skin protection to be used as wearable devices and allowing for controlled release of repellents. In this study, ethyl butylacetylaminopropionate (IR3535) was used as a human and environmental friendly active mosquito-repellent serving as a solvent to form functional poly(l-lactic acid) (PLLA) scaffolds by crystallization-based solid-liquid thermally induced phase separation. Crystallization of PLLA in the presence of IR3535 is faster than melt-crystallization of neat PLLA, and in the investigated concentration range from 5 to 50 mass % PLLA, its maximum crystallization rate increases with the PLLA content, by both, increases of the maximum crystal growth rate and of the nuclei density. By adjusting the polymer concentration and the crystallization temperature, microporous scaffolds of different fine structures are obtained, hosting the mosquito-repellent in intra- and interspherulitic pores for its intended later evaporation.