Fabricating thin metal layers and particularly observing their formation process in situ is of fundamental interest to tailor the quality of such a layer on polymers for organic electronics. In particular, the process of high power impulse magnetron sputtering (HiPIMS) for establishing thin metal layers has sparsely been explored in situ. Hence, in this study, we investigate the growth of thin gold (Au) layers with HiPIMS and compare their growth with thin Au layers prepared by conventional direct current magnetron sputtering (dcMS). Au was chosen because it is an inert noble metal and has a high scattering length density. This allows us to track the growing nanostructures via grazing incidence scattering. In particular, Au deposition on the polymer polystyrene (PS) with the respective structural analogues poly-4-vinlypyridine (P4VP) and polystyrene sulfonic acid (PSS) is studied. Additionally, the nanostructured layers on these different polymer films are further probed by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), X-ray reflectometry (XRR), and four-point probe measurements. We report that HiPIMS leads to smaller island-to-island distances throughout the whole sputter process. Moreover, an increased cluster density and an earlier percolation threshold are achieved compared to dcMS. Additionally, in the early stage, we observe a significant increase in coverage by HiPIMS, which is favorable for the improvement of the polymer-metal interface.

In the context of global climate change, the demand for new functional materials that are sustainable and environmentally friendly is rapidly increasing. Cellulose and lignin are the two most abundant raw materials in nature, and are ideal components for functional materials. The hydrophilic interface and easy film-forming properties of cellulose nanofibrils make them excellent candidates for natural biopolymer templates and network structures. Lignin is a natural UV-shielding material, as it contains a large number of phenolic groups. In this work, we have applied two routes for spray deposition of hybrid films with different laminar structures using surface-charged cellulose nanofibrils and water-based colloidal lignin particles. As the first route, we prepare stacked colloidal lignin particles and cellulose nanofibrils hybrid film through a layer-by-layer deposition. As the second route, we spray-deposite premixed colloidal lignin particles and cellulose nanofibrils dispersion to prepare a mixed hybrid film. We find that cellulose nanofibrils act as a directing agent to dominate the arrangement of the colloidal lignin particles in a mixed system. Additionally, cellulose nanofibrils eliminate the agglomerations and thus increase the visible light transparency while retaining the UV shielding ability. Our research on these colloidal lignin and cellulose nanofibril hybrid films provides a fundamental understanding of using colloidal lignin nanoparticles as functional material on porous cellulose-based materials, for example on fabrics.

Understanding materials with dimensions down to a few nanometers is of major importance for fundamental science as well as prospective applications. Structural transformation and phonon-confinement effects in the nanodiamonds (NDs) have been theoretically predicted below 3 nm in size. Here, we investigate the effect of size on the surface chemistry, microscopic structure, and Raman scattering of high-pressure high-temperature (HPHT) and detonation nanodiamonds (DNDs) down to 2-3 nm. The surface and size of NDs are controlled by annealing in air and ultracentrifugation resulting in three ND fractions. Particle size distribution (PSD) of the fractions is analyzed by combining dynamic light scattering, analytical ultracentrifugation, small-angle X-ray scattering, X-ray diffraction, and transmission electron microscopy as complementary techniques. Based on the obtained PSD, we identify size-dependent and synthesis-dependent differences of ND properties. In particular, interpretation of Raman scattering on NDs is revisited. Comprehensive comparison of detonation and pure monocrystalline HPHT NDs reveals effects of diamond core size and defects, chemical and temperature (in)stability, and limitations of current phonon confinement models. In addition, low-frequency Raman scattering in the 20-200 cm(-1) range is experimentally observed. The size dependence of this signal for both HPHT NDs and DNDs suggests that it may correspond to confined acoustic vibrational, "breathing-like" modes of NDs.

In this study, two types of stable Ag2S nanoparticle solutions with negative and positive zeta-potential and different stabilization mechanisms were synthesized by a chemical precipitation method. The first type was stabilized by adding 3-mercaptopropyl-trimethoxysilane (MPS) to provide steric stability of nanoparticles. It was found, that the MPS molecules could effectively stabilize the system covering about 20% of the nanoparticle's surface. For the second type, a simple method suggested in this work was used for the first time. This novel method is based on the addition of Na2S in great excess, which induces electrostatic stability of the solution with nanoparticles. The correlation between stability and parameters of nanoparticles has been established.

Drug loaded polymer micelles or nanoparticles are being continuously explored in the fields of drug delivery and nanomedicine. Commonly, a simple core-shell structure is assumed, in which the core incorporates the drug and the corona provides steric shielding, colloidal stability, and prevents protein adsorption. Recently, the interactions of the dissolved drug with the micellar corona have received increasing attention. Here, using small-angle neutron scattering, we provide an in-depth study of the differences in polymer micelle morphology of a small selection of structurally closely related polymer micelles at different loadings with the model compound curcumin. This work supports a previous study using solid state nuclear magnetic resonance spectroscopy and we confirm that the drug resides predominantly in the core of the micelle at low drug loading. As the drug loading increases, neutron scattering data suggests that an inner shell is formed, which we interpret as the corona also starting to incorporate the drug, whereas the outer shell mainly contains water and the polymer. The presented data clearly shows that a better understanding of the inner morphology and the impact of the hydrophilic block can be important parameters for improved drug loading in polymer micelles as well as provide insights into structure-property relationships.

A simple shell-creating technique for the synthesis of CdS nanoparticles covered by ZnS is presented, which also contributes to the understanding of their low quantum yield and luminescence intensity in water, which is usually below 0.01%. The CdS nanoparticles with about 0.8 nm thick ZnS shell were synthesized in a colloidal aqueous solution and stabilized by EDTA. The CdS carrier lifetime and the quantum efficiency is greatly increased. For the latter, values up to 2.7% were achieved. A mechanism for the CdS nanoparticle luminescence in the aqueous solution is proposed, which is based on radiative recombination of charge carriers with structural defects. It was found that the synthesis of CdS in air leads to the inclusion of oxygen atoms in the structure of nanoparticles, which strongly effects the luminescence spectrum. These results show that most of the CdS luminescence centers are localized inside the nanoparticle.

This study investigated the stabilization of cadmium sulfide (CdS) nanoparticles in aqueous solutions of the triblock copolymer Pluronic P123. The concentration of the added cadmium sulfide varied between 0.002 and 0.02 M. For the synthesis, sodium sulfide and cadmium chloride were both dissolved in aqueous P123 solutions with concentrations of 23 and 30 weight percent (wtp) of polymers. Both solutions were cooled to low temperatures and mixed in a heated sample cell. The stabilization of CdS nanoparticles was successful for both P123 concentrations. The stabilized nanoparticle-polymer solutions were investigated using ultraviolet-visible spectroscopy (UV-Vis) and small- and wide-angle-x-ray-scattering (SAXS/WAXS). In the absorption spectra measured by UV-Vis spectroscopy, no shift of the absorption edge, depending of the CdS concentration in solution is visible indicating a bulk like behavior. SAXS showed, that the distance between the Pluronic micelles is not changing in the lyotropic liquid crystal (LC) phase by adding CdS, but a significant rise of the scattering intensity was visible. We assume, that the nanoparticles are located in the micellar core. As proved by WAXS, in some cases even crystalline nanoparticles could be produced. This sample system consisting of polymeric micelles and nanoparticles can be seen as a model for studying the formation of nanoparticles because the crystallization process of the nanoparticles was enlarged form a timescale of nanoseconds to minutes.

The self-assembly of block copolymers has captured the interest of scientists for many decades because it can induce ordered structures and help to imitate complex structures found in nature. In contrast to proteins, nature's most functional hierarchical structures, conventional polymers are disperse in their length distribution. Here, we synthesized hydrophilic and hydrophobic polypeptoids via solid-phase synthesis (uniform) and ring-opening polymerization (disperse). Differential scanning calorimetry measurements showed that the uniform hydrophobic peptoids converge to a maximum of the melting temperature at a much lower chain length than their disperse analogs, showing that not only the chain length but also the dispersity has a considerable impact on the thermal properties of those homopolymers. These homopolymers were then coupled to yield amphiphilic block copolypeptoids. SAXS and AFM measurements confirm that the dispersity plays a major role in microphase separation of these macromolecules, and it appears that uniform hydrophobic blocks form more ordered structures.

The nanocomposite contained CdS nanoparticles of an average about 2 nm have been synthesized using three types of matrix based on silica in soft and hard conditions. As was demonstrated using the methods of spectrophotometry and luminescence in the UV, visible and NIR region, the optical properties of the nanocomposite significantly depend on the surrounding matrix and synthesis conditions. The results indicate that CdS nanoparticles contain a large number of atomic structure defects. It was found that the formation of nanoparticles within the oxygen-contained matrix effects on the long wave photoluminescence. The soft conditions of the synthesis allow to obtain CdS nanoparticles with a photoluminescence band at 2.59 and 2.67 eV, which is associated with exciton recombination.

In this paper we describe the optimization of transmission X-ray targets by Monte-Carlo simulation for a laboratory X-ray microscopy setup. We identified two optimal target layer thicknesses (0.1 μm and 0.7 μm) for a high-resolution target and a high-flux target. Measurements show a decrease in focal spot size by one third or an increase in X-ray flux by a factor of three compared to those of a standard micro-focus target. Focal spot sizes down to 154 nm and 260 nm are achievable with the optimized targets. Simulation results for the X-ray flux match well to the experimental results, whereas the results for the focal spot sizes still show discrepancies attributed to the simplified simulation setup.