Two-Step Wetting of Nanoporous Carbons: Small-Angle Scattering Analysis of Capillary Rise.

Numerous applications of nanoporous materials require their pores to be filled with liquids. In spite of its huge technological importance, the conditions for the wetting of nanometer-sized pores and its phenomenology are still poorly understood. We report on capillary rise experiments with water in carbon xerogels, with synchrotron small-angle scattering used to follow the process in situ at the nanometer scale.

Investigation of the link between first-order kinetic models of the in vitro digestion of native starches and the accompanying changes in their crystallinity and structure.

Starch is the main source of dietary energy for humans. In order to understand the mechanisms governing native starch in vitro digestion, digestion data for six starches [wheat, maize, (waxy) maize, rice, potato and pea] of different botanical sources were fitted with the most common first-order kinetic models, i.e.

Small-Angle Scattering Indicates Equilibrium Instead of Metastable Capillary Condensation in SBA-15 Mesoporous Silica.

Questions about the origin of the adsorption/desorption hysteresis in mesoporous materials are as old as sorption experiments themselves. The historical conception that underlines most existing methods to extract pore size distributions from sorption data assumes that adsorption is a metastable process and that desorption takes place at thermodynamic equilibrium. In this work, we measure nitrogen and argon sorption on a series of 14 SBA-15 ordered mesoporous silicas and use small-angle X-ray scattering to independently determine their pore sizes.

Hydrothermal treatments of starch impact reaction patterns during subsequent chemical derivatization.

Differences in derivatization patterns (using a fluorescent reagent, fluorescein isothiocyanate) of wheat, pea, and potato starches between native granular (NAT) starches and their respective annealed (ANN) and heat-moisture treated (HMT) starches were investigated to reveal structural changes associated with starch hydrothermal treatments. Size-exclusion chromatography with fluorescence and refractive index detection assessed the reactivity of amylose (AM), intermediate chains (IM and IM), and amylopectin branch chains (AP, AP, and AP) within the different starches. Shifts in X-ray diffraction patterns of HMT starches and in the gelatinization properties of both ANN and HMT starches confirmed molecular rearrangement.

Induction of Maize Starch Gelatinization and Dissolution at Low Temperature by the Hydrotrope Sodium Salicylate.

Complete aqueous dissolution of starch requires the use of temperatures exceeding 100 °C. During and after cooling of the resultant aqueous solutions, starch polymers precipitate by aggregation and crystallization. Low-temperature gelatinization and dissolution of maize starch (MS) is induced, and the stability of the resultant solutions is enhanced when they contain the hydrotrope sodium salicylate (NaSal).

Extrusion and Injection Molding of Poly(3-Hydroxybutyrate-co-3-Hydroxyhexanoate) (PHBHHx): Influence of Processing Conditions on Mechanical Properties and Microstructure.

Biobased and biodegradable polyhydroxyalkanoates (PHAs) have great potential as sustainable packaging materials. However, improvements in their processing and mechanical properties are necessary. In this work, the influence of melt processing conditions on the mechanical properties and microstructure of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is examined using a full factorial design of experiments (DoE) approach.

The Extent of Interlayer Bond Strength during Fused Filament Fabrication of Nylon Copolymers: An Interplay between Thermal History and Crystalline Morphology.

One of the main drawbacks of Fused Filament Fabrication is the often-inadequate mechanical performance of printed parts due to a lack of sufficient interlayer bonding between successively deposited layers. The phenomenon of interlayer bonding becomes especially complex for semi-crystalline polymers, as, besides the extremely non-isothermal temperature history experienced by the extruded layers, the ongoing crystallization process will greatly complicate its analysis. This work attempts to elucidate a possible relation between the degree of crystallinity attained during printing by mimicking the experienced thermal history with Fast Scanning Chip Calorimetry, the extent of interlayer bonding by performing trouser tear fracture tests on printed specimens, and the resulting crystalline morphology at the weld interface through visualization with polarized light microscopy.

Phase Behavior and Polymorphism of Saturated and Unsaturated Phytosterol Esters.

This study investigated how the physicochemical characteristics of phytosterol esters are influenced by the chain length and degree of unsaturation of the fatty acid ester moiety. Saturated and unsaturated phytosterol esters (PEs) were synthesized by the esterification of different types of fatty acids (stearic, palmitic, lauric, oleic, and linoleic acid) to β-sitosterol. The non-isothermal crystallization and melting behavior of the pure PEs were analyzed.

Thermal unequilibrium of strained black CsPbI thin films.

The high-temperature, all-inorganic CsPbI perovskite black phase is metastable relative to its yellow, nonperovskite phase at room temperature. Because only the black phase is optically active, this represents an impediment for the use of CsPbI in optoelectronic devices. We report the use of substrate clamping and biaxial strain to render black-phase CsPbI thin films stable at room temperature.

Isothermal Crystallization Kinetics of Palm Oil as Influenced by Addition of a Commercial Phytosterol Ester Mixture.

In literature there is good agreement on the health-promoting effects of phytosterols. However, addition of phytosterol esters (PEs) to lipid (containing food products) may influence its crystallization behavior. This study investigated the crystallization kinetics of palm oil (PO) after addition of PEs in high concentrations (≥10%).

Microstructure of Pharmaceutical Semicrystalline Dispersions: The Significance of Polymer Conformation.

The microstructure of pharmaceutical semicrystalline solid dispersions has attracted extensive attention due to its complexity that might result in the diversity in physical stability, dissolution behavior, and pharmaceutical performance of the systems. Numerous factors have been reported that dictate the microstructure of semicrystalline dispersions. Nevertheless, the importance of the complicated conformation of the polymer has never been elucidated.

Effect of the GO Reduction Method on the Dielectric Properties, Electrical Conductivity and Crystalline Behavior of PEO/rGO Nanocomposites.

The effect of the reduction method to prepare reduced graphene oxide (rGO) on the melt linear viscoelastic properties, electrical conductivity, polymer matrix crystalline behavior and dielectric properties of PEO-rGO nanocomposites was investigated. Reduction was performed chemically with either sodium borohydride (NaBH₄) or hydrazine monohydrate (N₂H₄·H₂O) or both reduction agents consecutively as well as thermally at 1000 °C. The different reduction methods resulted in exfoliated rGO sheets with different types and amounts of remaining functional groups, as indicated by FT-IR, Raman, TGA and XRD characterization.

The effect of adding a commercial phytosterol ester mixture on the phase behavior of palm oil.

The objective of this study was to investigate in depth the non-isothermal crystallization and melting behavior of binary blends of palm oil (PO) with a commercial, multi-component phytosterol ester (PE) mixture. DSC and time-resolved synchrotron X-ray diffraction (XRD) experiments were conducted on blends with a PE concentration from 0 to 100% at intervals of 10% for DSC and 20% for XRD. Based on XRD, two different ordered structures were identified in pure the PEs.

Methodologies for producing amylose: A review.

Three main in vitro approaches can be distinguished for obtaining amylose (AM): enzymatic synthesis, AM leaching, and AM complexation following starch dispersion. The first uses α-d-glucose-1-phosphate (G1P), a glucosyl primer with a degree of polymerization (DP) of at least 4 and phosphorylase (EC 2.4.

Effect of Compression on the Molecular Arrangement of Itraconazole-Soluplus Solid Dispersions: Induction of Liquid Crystals or Exacerbation of Phase Separation?

Predensification and compression are unit operations imperative to the manufacture of tablets and capsules. Such stress-inducing steps can cause destabilization of solid dispersions which can alter their molecular arrangement and ultimately affect dissolution rate and bioavailability. In this study, itraconazole-Soluplus solid dispersions with 50% (w/w) drug loading prepared by hot-melt extrusion (HME) were investigated.

Isothermal Crystallization Behavior of Cocoa Butter at 17 and 20 °C with and without Limonene.

Differential scanning calorimetry and real-time X-ray diffraction using synchrotron radiation were used to elucidate isothermal cocoa butter crystallization at 17 and 20 °C in the absence and presence of different limonene concentrations. At 17 °C, a three-step crystallization process was visible for pure cocoa butter, whereby first an unknown structure with long spacings between a 2L and 3L structure was formed that rapidly transformed into the more stable α structure, which in turn was converted into more stable β' crystals. At 20 °C, an α-mediated β' crystallization was observed.

Poly(alanine): Structure and Stability of the D and L-Enantiomers.

High-performance, biobased materials can potentially be manufactured from polymerized α-amino acids (α-polypeptides). This paper reports on the synthesis, structure, and properties of both polyalanine enantiomers (PLAla and PDAla). The molecular structure of the polypeptide chains, their molecular weight, and polydispersity were investigated by (1)H NMR, MALDI-TOF, and size-exclusion chromatography.

Mesoscale Characterization of Nanoparticles Distribution Using X-ray Scattering.

The properties of many functional materials depend critically on the spatial distribution of an active phase within a support. In the case of solid catalysts, controlling the spatial distribution of metal (oxide) nanoparticles at the mesoscopic scale offers new strategies to tune their performance and enhance their lifetimes. However, such advanced control requires suitable characterization methods, which are currently scarce.

Simultaneous Synchrotron WAXD and Fast Scanning (Chip) Calorimetry: On the (Isothermal) Crystallization of HDPE and PA11 at High Supercoolings and Cooling Rates up to 200 °C s(-1).

An experimental setup, making use of a Flash DSC 1 prototype, is presented in which materials can be studied simultaneously by fast scanning calorimetry (FSC) and synchrotron wide angle X-ray diffraction (WAXD). Accumulation of multiple, identical measurements results in high quality, millisecond WAXD patterns. Patterns at every degree during the crystallization and melting of high density polyethylene at FSC typical scanning rates from 20 up to 200 °C s(-1) are discussed in terms of the temperature and scanning rate dependent material crystallinities and crystal densities.

Highly efficient hyperbranched CNT surfactants: influence of molar mass and functionalization.

End-group-functionalized hyperbranched polymers were synthesized to act as a carbon nanotube (CNT) surfactant in aqueous solutions. Variation of the percentage of triphenylmethyl (trityl) functionalization and of the molar mass of the hyperbranched polyglycerol (PG) core resulted in the highest measured surfactant efficiency for a 5000 g/mol PG with 5.6% of the available hydroxyl end-groups replaced by trityl functions, as shown by UV-vis measurements.

Global and local superconductivity in boron-doped granular diamond.

Strong granularity-correlated and intragrain modulations of the superconducting order parameter are demonstrated in heavily boron-doped diamond situated not yet in the vicinity of the metal-insulator transition. These modulations at the superconducting state (SC) and at the global normal state (NS) above the resistive superconducting transition, reveal that local Cooper pairing sets in prior to the global phase coherence.

Importance of thiol-functionalized molecules for the structure and properties of compression-molded glassy wheat gluten bioplastics.

High-temperature compression molding of wheat gluten at low water levels yields a rigid plastic-like material. We performed a systematic study to determine the effect of additives with multiple thiol (SH) groups on gluten network formation during processing and investigate the impact of the resulting gluten network on the mechanical properties of the glassy end product. To this end, a fraction of the hydroxyl groups of different polyols was converted into SH functionalities by esterifying with 3-mercaptopropionic acid (MPA).

The role of specific interaction in phase behavior of polyelectrolyte-surfactant-water mixtures.

Aqueous phase behavior and structures of phases were studied in systems containing sodium poly(styrenesulfonate), NaPSS, and complex salt CTAPSS, formed between cetyltrimethylammonium cations, CTA+, and PSS- anions. It was shown that hydrophobic interaction of the polyion styrene groups with surfactant aggregates, which supports the strong electrostatic attraction between CTA+ and PSS-, has a significant effect on phase behavior and structures. Only the disordered micellar (L1) and the ordered hexagonal (H1) phase were found that are connected over a broad two-phase region of L1-H1 coexistence.

Impact of acid and alkaline pretreatments on the molecular network of wheat gluten and on the mechanical properties of compression-molded glassy wheat gluten bioplastics.

Wheat gluten can be converted into rigid biobased materials by high-temperature compression molding at low moisture contents. During molding, a cross-linked protein network is formed. This study investigated the effect of mixing gluten with acid/alkali in 70% ethanol at ambient temperature for 16 h followed by ethanol removal, freeze-drying, and compression molding at 130 and 150 °C on network formation and on types of cross-links formed.

Molecular and morphological aspects of annealing-induced stabilization of starch crystallites.

A unique series of potato (mutant) starches with highly different amylopectin/amylose (AP/AM) ratios was annealed in excess water at stepwise increasing temperatures to increase the starch melting (or gelatinization) temperatures in aqueous suspensions. Small-angle X-ray scattering (SAXS) experiments revealed that the lamellar starch crystals gain stability upon annealing via thickening for high-AM starch, whereas the crystal surface energy decreases for AM-free starch. In starches with intermediate AP/AM ratio, both mechanisms occur, but the surface energy reduction mechanism prevails.