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All‐small‐molecule organic solar cells (ASM‐OSCs), which consist of small‐molecule donors and acceptors, have recently been studied extensively to eliminate the batch‐to‐batch variation from polymer‐based donor or acceptor. On the other hand, the control of their active layer morphology is more challenging due to the similar chemical structure and miscibility of small‐molecule donor and small‐molecule accepter. Hence, this study develops a dual‐additive‐driven morphology optimization method for ASM‐OSCs based on BTR‐Cl:Y6. One solid additive – 1,4‐diiodobenzene (DIB) and one liquid additive – diiodomethane (DIM) are selected, making use of their distinct interaction mechanisms with Y6 and BTR‐Cl. It is found that DIB can form a eutectic phase with Y6, which can increase the intermolecular interactions and modulate the acceptor phase separation, while the simultaneous volatilization of DIM suppresses the over‐aggregation of BTR‐Cl during the film casting process. As a result of the synergistic morphology tuning, the optimized device delivers a power conversion efficiency (PCE) as high as 15.2%, among the highest PCE reported to date for binary ASM‐OSCs without solvent annealing treatment. This work demonstrates the potential of morphology tuning via the incorporation of dual additives into ASM‐OSCs, enabling them to achieve comparable efficiencies to those of conventional polymer/small‐molecule based OSCs. [ABSTRACT FROM AUTHOR]

Liposome development is of great interest owing to increasing requirements for efficient drug carriers. The structural features and thermal stability of such liposomes are crucial in drug transport and delivery. Reported here are the results of the structural characterization of PEGylated liposomes via small‐ and wide‐angle X‐ray scattering and an asymmetric flow field‐flow fractionation (AF4) system coupled with differential refractive‐index detection, multi‐angle light scattering (MALS) and dynamic light scattering. This integrated analysis of the exemplar PEGylated liposome formed from hydrogenated soy phosphatidylcholine (HSPC) with the addition of cholesterol reveals an average hydrodynamic radius (Rh) of 52 nm with 10% polydispersity, a comparable radius of gyration (Rg) and a major liposome particle mass of 118 kDa. The local bilayer structure of the liposome is found to have asymmetric electronic density profiles in the inner and outer leaflets, sandwiched by two PEGylated outer layers ca 5 nm thick. Cholesterol was found to effectively intervene in lipid chain packing, resulting in the thickening of the liposome bilayer, an increase in the area per lipid and an increase in liposome size, especially in the fluid phase of the liposome. These cholesterol effects show signs of saturation at cholesterol concentrations above ca 1:5 cholesterol:lipid molar ratio. [ABSTRACT FROM AUTHOR]

This study provides new evidence on a long postulated mechanism of phase separation in a polymer/fullerene mixture during spin coating for controlled nanodomains of oriented crystallization and heterojunctions that favor applications in polymer solar cells (PSCs). The simultaneous nanoscale phase separation and crystallization during spin coating of the mixture are traced using in situ grazing-incidence small- and wide-angle X-ray scattering. Combined with the complimentary results from time-resolved optical reflectance spectroscopy, transient stratification of the liquid film during the transition from the flow- to evaporation-dominated stage of spin coating is disclosed; the vertical liquid-liquid phase separation incubates a supersaturated skin layer where fullerene aggregation and polymer crystallization occur and develop concomitantly. Shortly after the transition, the near-surface structural development is largely pinned, leaving the solvent-rich bottom layer to diminish via solvent diffusion and evaporation through the thickened skin layer that finally condenses into the spin-coated film upon solvent depletion. The shear-enhanced surface layering and supersaturation for the surface-down nanostructural development are unexpected in all the existing structural models for PSCs. The mechanistic understanding of coupled vertical phase separation and local nanosegregation provides new insights and alternative strategy to the morphology control of spin-cast PSC active layers in particular and various solution-processed polymeric films in general. [ABSTRACT FROM AUTHOR]

Polymer solar cells (PSCs) based on fullerene derivatives often require additives to optimize active layer morphology. Here, the novel additive 1-naphthalenethiol (SH-na) is proposed for processing the PSC active layer of PTB7:PC71BM. Spin-casting with SH-na as additive achieves a power conversion efficiency (PCE) of 7.3%, compared to 6.7% for preparations containing the conventional 1,8-diiodooctane additive. Dipping of the active layer into a methanol solution of critical SH-na concentration increases the PCE further to 8.75%. This is mainly due to an improved open-circuit voltage (from 0.72 to 0.79 V) together with a high achieved fill factor of 0.70. The improved PCE is correlated to the morphology optimization according to measurements of grazing incidence small/wide-angle X-ray scattering, neutron reflectivity, atomic force microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The integrated results suggest that the halogen-free additive SH-na can form hydrogen bonds with both PTB7 and PC71BM, resulting in substantially improved PTB7 crystallization and multi-length-scale PC71BM dispersion for appropriate aggregation and networks. The subsequent dipping treatment with SH-na further modifies the active layer morphology for a more PC71BM-enriched surface and better PC71BM networks in the bulk film for an optimized electron-to-hole mobility ratio of 2.04, hence resulting in improved device performance. [ABSTRACT FROM AUTHOR]

A novel one-trough synthesis via an air-water interface is demonstrated to provide hexagonally packed arrays of densely spaced metallic nanoparticles (NPs). In the synthesis, a mesostructured polyoxometalate (POM)-silicatropic template (PSS) is first self-assembled at the air-water interface; upon UV irradiation, anion exchange cycles enable the free-floating PSS film to continuously uptake gold precursors from the solution subphase for diffusion-controlled and POM-site-directed photoreduction inside the silica channels. NPs ≈ 2 nm can hence be homogeneously formed inside the silica-surfactant channels until saturation. As revealed via X-ray diffraction, small-angle X-ray scattering (SAXS), grazing incidence SAXS, and transmission electron microscopy, the Au NPs directed by the PSS template are arrayed into a 2D hexagonal lattice with inter-channel spacing of 3.2 nm and a mean along-channel NP spacing of 2.8 nm. This corresponds to an ultra-high number density (≈1019 NPs cm−3) of narrowly spaced Au NPs in the Au-NP@PSS composite, leading to 3D densely deployed hot-spots along and across the mesostructured POM-silica channels for surface-enhanced Raman scattering (SERS). Consequently, the Au-NP@PSS composite exhibits prominent SERS with 4-mercaptobenzoic acid (4-MBA) adsorbed onto Au NPs. The best 4-MBA detection limit is 5 n m, with corresponding SERS enhancement factors above 108. [ABSTRACT FROM AUTHOR]

Morphological evolution and phase transformation of metastable intermediate precipitates are critical to their mechanical properties for the non-isothermal processing. During the non-isothermal precipitation, the formation of the new phases usually couples with structural evolution. Traditional structural characterization has limitation to resolve comprehensive changes simultaneously. In this study, we report direct observation, precipitation sequence, and the details of concurrent morphological and structural changes of various intermediate precipitates during non-isothermal heating in the Al–Cu systems with different pretreatments. The structural heterogeneity during the non-isothermal precipitation processes is resolved into coexistence of two different precipitate phases and quantitatively studied in terms of the phase transition and the morphological evolution. This paper presents the in situ small- and wide-angle synchrotron x-ray scattering (SAXS and WAXS) to refine and to identify the mixed structural information during multiple precipitation stages. The WAXS results show that the precipitation sequence is θ″ → (θ″ + θ′) → θ′ → (θ′ + θ) → θ upon heating. Due to the fact of the specifically oriented SAXS intensity, the evolution of the aforementioned phase transformation is resolved by the refinement of the SAXS intensity integrated over the selected area. These methods reveal multiscale information that is not trivial comparing to the traditional characterization methods. [ABSTRACT FROM PUBLISHER]

Abstract: We have investigated the crystallization effect on the phase separation of a poly(ɛ-caprolactone) and poly(ethylene glycol) oligomer (PCL/PEGo) blending system using simultaneous small-angle light scattering and differential scanning calorimetry (SALS/DSC) as well as simultaneous small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and DSC (SAXS/WAXS/DSC). When the PCL/PEGo system, of a weight ratio of 7/3, is quenched from a melt state (160°C) to temperatures below the spinodal point and the melting temperature of PCL (63°C), the structural evolution observed exhibits characteristics of (I) early stage of spinodal decomposition (SD), (II) transient pinning, (III) crystallization-induced depinning, and (IV) diffusion-limited crystallization. The time-dependent scattering data of SALS, SAXS and WAXS, covering a wide range of length scale, clearly show that the crystallization of PCL intervenes significantly in the ongoing viscoelastic phase separation of the system, only after the early stage of SD. The effect of preordering before crystallization revives the structural evolution pinned by the viscoelastic phase separation. The growth of SAXS intensity during the preordering period conforms to the Cahn–Hilliard theory. In the later stage of the phase separation, the PCL-rich matrix, of spherulite crystalline domains developed due to the faster crystallization kinetics, traps the isolated PEGo-rich domains of a slower viscoelastic separation. [Copyright &y& Elsevier]

Abstract: With specific annealing schemes applied to a neat polystyrene-block-poly(ethylene oxide) (SE) and its composites with cadmium sulfide quantum dots (CdS QD), we have observed microdomain structures and phase transitions in the system using temperature-resolved small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Both TEM images and SAXS results show clearly that incorporation of surfactant-tethered CdS QD preferentially into PEO blocks leads to increases in thermal stabilities of both bcc-packed lattice (referred as long-range order) and microdomains themselves in the sphere-forming SE/CdS composites. The bcc-packed lattice in the SE/CdS composites sustains better than that in the neat SE, during a temperature elevation to ∼160°C, at which the bcc-packed SE/CdS spheres start to transform into micelles with a short-range liquid-like order. Quantitative model analysis shows that the PEO/CdS micelles can retain their size in the SE/CdS composites up to 200°C, whereas the PEO micelles shrink after the softening of the PS matrix around 100°C, and disassociate largely into the PS matrix of the neat SE at 160°C. [Copyright &y& Elsevier]

Abstract: We have studied the structure and phase transition characteristics of the fullerenes (C60)-embedded lipid bilayers. With small-angle neutron scattering (SANS), we have observed a degradation of bilayer ordering and a suppression effect on the phase transitions of the host vesicle bilayers of dipalmitoylphosphatidylcholine (DPPC), due to the embedment of fullerenes. The fullerene-embedded lipid system with substrate-oriented bilayers is also investigated using X-ray reflectivity and grazing incident small-angle X-ray scattering (GISAXS). In the depth direction, the multilamellar peaks observed in the X-ray reflectivity profile for the oriented DPPC/C60 bilayers reveal a larger head-to-head distance DHH of 50.6Å and a bilayer spacing D of 59.8Å, compared to the DHH=47.7Å and D=59.5Å for a pure DPPC membrane measured at the same conditions. Furthermore, the lipid head layers and water layers in the extracted electron density profile for the complex system are highly smeared, implying a fluctuating or corrugated structure in this zone. Correspondingly, GISAXS for the oriented DPPC/C60 membrane reveals stronger diffuse scatterings along the membrane plane than that for the pure DPPC system, indicating a higher in-plane correlation associated with the embedded fullerenes. [Copyright &y& Elsevier]

Abstract: We have studied the structure of a high-porous silica thin film with pore sizes in nanometer scale using X-ray reflectivity and small angle X-ray scattering in grazing incidence geometry. The reflectivity data provide the information of surface and interface characteristics, density–depth profile, and porosity of the xerogel film. Whereas the grazing incidence small angle X-ray scattering results reveal the internal structure of the porous film, including pore shape and size, and averaged inter-pore spacing. It is demonstrated that the combination of these two techniques is a powerful structural characterization tool to porous thin films. [Copyright &y& Elsevier]

Time‐resolved, grazing incidence small‐ and wide‐angle X‐ray scattering together with in situ UV‐Vis reflectance spectroscopy unveil the surface layering in the early stage of spin‐coating of a polymer‐fullerene mixture, which drives surface‐down local phase separation over the flow‐ to evaporation‐dominated stages of film formation for mutually confined and intercalated nanodomains of polymer crystallites and fullerene aggregates. This is reported by Chun‐Jen Su, U‐Ser Jeng, and co‐workers in article number 1601842. [ABSTRACT FROM AUTHOR]

Based on results of small-angle X-ray scattering and differential scanning calorimetric measurements, the equilibrium melting temperature and basal surface energy ( σe) of crystalline poly(9,9-di- n-octyl-2,7-fluorene) (PFO) were preliminarily estimated as ca 451.6 K and 0.084 J m−2, respectively, via Gibbs–Thomson analysis. This σe value leads to a value of 76 kJ mol−1 for the work of fold that greatly exceeds the values for typical polymers, reflecting the semi-rigid nature of the PFO backbone and consistent with the large-loop folds proposed earlier for this particular conjugated-backbone polymer. This is in strong contrast to the commonly held belief that conjugated polymers are generally too rigid to form folded-chain lamellar crystals. [ABSTRACT FROM AUTHOR]

Structural evolution of poly(l-lactide) during cold-crystallizationat 80 °C was examined via simultaneous small/wide-angle X-rayscattering (SAXS/WAXS), Fourier-transform infrared spectroscopy (FTIR),and differential scanning calorimetry (DSC). The incipient α′crystals of loosely packed 107helices, formed at tc= 200 s as detected via both WAXS and FTIR,were hardly identifiable via SAXS or DSC due to its low values ofdensity contrast or latent heat (initially ΔHα′≈ 12 J/g, gradually reaching 74J/g near the end of crystallization, in contrast to ΔHα≈ 140 J/g), was already largein lateral size (with coherence length Λ200/110≈35 nm, increasing to 50 nm during tc=200–400 s and remained little changed afterward). Once formed,the α′ crystals underwent continuous and persistent perfectionfor decreasing lattice spacing and partially transformed to smallerα crystals (tc≈ 800–1800s, up to a saturated population ratio of 1:4 between α and α′phases), followed by slower yet steady increases in SAXS invariantwithout significant changes in the α and α′ contentsfor tc> 1800 s. It is concluded thatthe α′ form is a transient structure of continuouslyincreasing packing density and latent heat toward the α form,reminiscent of the mesomorphic phase as precursors to stable crystalsin other polymers. Nevertheless, transformation to α crystalsoccurred when the lattice parameters of the α′ phasewere closer but still finitely different from those of the αphase and that the conversion between the two phases was limited inthis isothermal case. Both observations suggest that, in spite ofthe transient nature of the α′ phase, the final transformationstep to the stable α form is still achieved via a first-orderroute. [ABSTRACT FROM AUTHOR]

Abstract: We have studied the bilayer thinning structure of unilamellar vesicles (ULV) of a phospholipid 1,2-dierucoyl-sn-glycero-3-phosphocholine (di22:1PC) upon binding of melittin, a water-soluble amphipathic peptide. Successive thinning of the ULV bilayers with increasing peptide concentration was monitored via small-angle X-ray scattering (SAXS). Results suggest that the two leaflets of the ULV of closed bilayers are perturbed and thinned asymmetrically upon free peptide binding, in contrast to the centro-symmetric bilayer thinning of the substrate-oriented multilamellar membranes (MLM) with premixed melittin. Moreover, thinning of the melittin-ULV bilayer associates closely with peptide concentration in solution and saturates at ~4%, compared to the ~8% maximum thinning observed for the correspondingly premixed peptide-MLM bilayers. Linearly scaling the thinning of peptide-ULV bilayers to that of the corresponding peptide-MLM of a calibrated peptide-to-lipid ratio, we have deduced the number of bound peptides on the ULV bilayers as a function of free peptide concentration in solution. The hence derived X-ray-based binding isotherm allows extraction of a low binding constant of melittin to the ULV bilayers, on the basis of surface partition equilibrium and the Gouy–Chapman theory. Moreover, we show that the ULV and MLM bilayers of di22:1PC share a same thinning constant upon binding of a hydrophobic peptide alamethicin; this result supports the linear scaling approach used in the melittin-ULV bilayer thinning for thermodynamic binding parameters of water-soluble peptides. [Copyright &y& Elsevier]

Abstract: The present study employs small-angle X-ray scattering (SAXS) to investigate the water-swollen structures of two types of Nafion membranes, commercial Nafion 117 membranes and the membranes synthesized from the Nafion precursor, subjected to gamma radiation. The membrane structure can be characterized by two-length scales, comprised the long-range order of lamellar crystalline domains in the matrix and the local order of ionic cluster domains. Both the long-range order lamella and local order cluster in the membranes are significantly affected by the radiation-induced cross-linking. We have extended a local order model to take into account the polydispersity effect, which can more satisfactorily reproduce the ionomer SAXS peak than other existing models. The structural parameters determined from the SAXS model analysis are self-consistent with those obtained from the model-independent Porod analysis. The modified membrane structure by the radiation cross-linking is very helpful for developing a high performance and low cost of direct methanol fuel cells. [Copyright &y& Elsevier]

Abstract: Using the X-ray source generated by a newly installed superconducting wavelength shifter at the Taiwan Light Source storage ring of the National Synchrotron Radiation Research Center (NSRRC), we have constructed an X-ray beamline equipped with a small angle X-ray scattering (SAXS) station for nanostructure research. This beamline can deliver a photon flux of ∼3×1011 photons/s in the energy range of 5–22keV, with a beam divergence of ∼0.3mrad in vertical direction. With the new SAXS end station we have studied PtRu nanoparticles embedded in fine carbon grains using anomalous SAXS. We illustrate other features of the SAXS instrument with a few more measurements on phase transitions of diblock-polymers, structural evolution of aluminium alloys under an artificial aging at high temperature, and folding and unfolding of lysozyme in aqueous solutions. [Copyright &y& Elsevier]

Abstract Conductive polymers take much interest because of their electroactive definition as new generation smart biomaterials beside of their potential usage in proton exchange membrane fuel cells. Partially sulfonated styrene-(ethylene-butylene)-styrene (sSEBS) triblock copolymer based films (coded SEBS68 with the content of 68% SEBS, 5% PP, 26,5% Wax and 0,5% stabilizer) have been focused in the present study. Chemical manipulations have been done during the synthesis of the films for formation of nano-scale cylindrical like globular and lamellar like nematic aggregations. Association of the nano aggregations and nano-domains in the films were investigated by using small- and wide-angle X-ray scattering methods. Microscale surface morphologies and features were also examined by a compact non-contact 3D surface profiler system. The results show that the changes in the nanostructures and the surface morphologies are dependent on sulfonation time. With sulfonation time of 4 min, the system could reach optimum physico-chemical properties, including the optimized size of phase segregation tunnels. It was also found that the modified polymer morphologies with nanostructural features are effective on antimicrobial activities against the different test microorganisms studied. Graphical abstract Image 1 Highlights • Nano structured electro- and bio-active SSEBS copolymers have been obtained by sulfonation. • Nano and micro scale characterizations showed structural changes by the effect of sulfonation. • Effective radius of nanoglobules increase up to 4 min sulfonation time and then decrease. • 4 min sulfonation causes optimum nanoglobular size and new microsized clustering. • The SSEB-films exhibited stronger antibacterial than antifungal activity. [ABSTRACT FROM AUTHOR]

The conformations and compositions of a proton-translocating pyrophosphatase Vigna radiata H+-PPase (VrPPase), stabilized by either detergent molecules or embedded in a lipid nanodisc in aqueous solution, are revealed using size exclusion chromatography coupled small-angle X-ray scattering (SEC-SAXS) with online UV–Vis absorption and refractive index (RI) detections. The integrated analysis of the scattering and optical data indicates that the large VrPPase dimer can be embedded successfully into the POPC nanodisc, with the transmembrane region immersed into the lipid aliphatic chains. The corresponding structural parameters of the protein-nanodisc complex are determined using an analytical core-multishell elliptical cylinder model. After binding with imidodiphosphate (IDP) to mimic the substrate (PP i) binding, the VrPPase embedded in the nanodisc shows no obvious structural changes. Correspondingly, the detergent-solubilized tetramers display a relatively prominent structural response to the IDP binding. About 450 n-decyl-β- d -maltopyranoside molecules are present in the detergent corona surrounding the hydrophobic area of the protein tetramer, making it difficult to attribute the structural changes observed solely to the VrPPase. Nevertheless, the combined measurements and analysis of the SEC-SAXS advance the understanding of the two types of membrane-protein complexes in terms of their compositions and structural features. [Display omitted] • Solution structures of a membrane protein (VrPPase) are studied using SEC-SAXS, UV–vis absorption and RI detection. • VrPPase dimer is embedded into an especially enlarged POPC nanodisc confined with a membrane scaffold protein. • VrPPase tetramer is stabilized in solution by ca. 450 detergent molecules surrounding the transmembrane region. • Structure models of detergent-VrPPase without and with imidodiphosphate for mimicking substrate binding are presented. [ABSTRACT FROM AUTHOR]

Melt-crystallization of syndiotactic polystyrene (sPS) is studied using simultaneous small/wide angle X-ray scattering (SAXS/WAXS). Emergence, intensification, and saturation of WAXS reflections within 120 s at isothermal crystallization temperature T c = 250 °C after quenching from 300 °C illustrate crystallinity development through successive nucleation of instantaneously stabilized crystallites of lateral ( hk 0) coherence length Λ ≈ 75 nm. The corresponding SAXS profiles exhibit increased density heterogeneity due to formation of nanograins; fitting of time-resolved SAXS data with a model of arrayed disks reveals slightly thickened ( l c = 7.4–8.4 nm) disks of radius R ≈ 9 nm and long period L ≈ 19 nm with polydisperse stacking number slowly enhanced from an average of 1.2 to 2.4. The moderate ratio of Λ/ 2 R ≈ 4 indicates imperfect coalescence of nanograins in the lamellar assembly process. More importantly, with successively increased T c from 250 to 260 °C the development of density heterogeneity of SAXS invariant Q inv is found to precede that of the WAXS-determined crystallinity X c increasingly more, suggesting a precursor mesophase with non-crystalline nanograins. Avrami analysis for the developments of X c and Q inv further reveals the same Avrami exponent n ≈ 3, consistent with heterogeneous nucleation of crystallites; the corresponding Avrami rate constant κ 1/n ( T c ) extracted from X c is correlated to the crystal growth rates G ( T c ) described by the Hoffman-Lauritzen theory with a common surface-nucleation rate constant K g . A lateral surface energy σ ≈ 17 mJ m −2 can be deduced on the basis of K g using previously determined fold surface energy σ e ≈ 27 mJ m −2 . Correspondingly, κ 1/n ( T c ) extracted from Q inv is described by a mesophase model proposed by Strobl with a zero-growth temperature of the nanograin mesophase ca. 30 K below the β-crystal melting point of sPS. Together, these results suggest that sPS melt-crystallization proceeds with nucleation of non-crystalline nanograins (SAXS-before-WAXS regime) at the crystal growth front, followed by crystallization of the nanograins with similar kinetics to sustain the growth front. Branching/twisting can occur at the lamellar growth front due to frustrated nanograin alignment, favoring the microscopically observed sheaf-like crystal morphology. [ABSTRACT FROM AUTHOR]

• Highly stretchable and self-healing materials based on metal–ligand coordination. • Choice of solvents can significantly affect the results of fabricated products. • SAXS/WAXS models constructed under different scenarios. • Robust skin-inspired pyramidal sensors can be performed over 100 cycles. Self-healing and stretchable materials have attracted considerable attention due their wide potential applications in developing human–machine interfaces. However, it remains a great challenge to achieve polymeric materials capable of both self-healing at room temperature and fast elastic recoverability after cuts or high stretching. We report herein a new material based on tolylene 2,4-diisocyanate elastomer (PTD) terminated with 4,4′-Bis(hydroxymethyl)-2,2′-bipyridine (bpy), having autonomously self-healing and ultra-fast stretching recovery properties, through incorporating trans -octahedral metal–ligand coordination of Zn2+ or Ni2+ ions with the bpy moieties; both Zn- and Ni-bpyPTD show combined properties of water-resistant, anti-bacteria, low toxicity and high transparency, and of respective emphases in self-healing and mechanical strength. The underlying mechanism is associated with the trans -octahedral metal–ligand coordination and their organized nanostructures as effective crosslinking sites in the bpyPTD matrix of rich hydrogen bonding, as revealed by X-ray absorption and in-situ small- and wide-angle X-ray scattering. Particularly, when fabricated into a pressure sensor, Ni-bpyPTD exhibits synchronized and durable mechanical and electrical responses under a repetitive cycling tensile testing up to 300% strain within 60 s, over 100 cycles, and would serve as a promising material for skin-inspired tactile sensing. [ABSTRACT FROM AUTHOR]

The effect that processing additives have upon the lifetime of PCPDTBT-based OPVs has been investigated. The results show conclusively that whilst ODT processing additive enhances the initial performance of PCPDTBT:PCBM OPVs, it is detrimental to their long term performance, when measured under light soaking at 1 Sun of irradiance. Results are shown for both encapsulated and non-encapsulated devices. Topographical and morphological measurements made using AFM and small- and wide-angle X-ray scattering of active layers show that there are greater morphological changes of devices fabricated with the 1,8-octanedithiol upon light soaking, revealing a relatively venerable morphology of the active layer processed with the additive, when subject to light soaking. [ABSTRACT FROM AUTHOR]

Abstract: We report the first quantitative demonstration of the use of particle tracking microrheology (PTμR) in probing the pH-induced coil–globule transition (CGT) of poly-2-vinylpyridine (P2VP). The calculated radii R of the P2VP coils and globules are found to vary with molecular weight M respectively according to: R∝M 0.592 ± 0.006 and R∝M 0.339 ± 0.010, in excellent agreement with the classical Flory–de Gennes theory. The sphere-like small-angle X-ray scattering spectrum and the sharp rise in pyrene emission suggest that the observed CGT is likely triggered by drastic changes in the chain's hydrophobicity, sensitive to the degree of protonation near the coil–globule transition point. A more in-depth theoretical analysis further reveals that the phenomenon strongly depends on interplays between excluded-volume, electrostatic, and hydrophobic interactions at the subunit level of a P2VP chain. This new application of PTμR could have potential uses in exploring the physics of a variety of polymer systems at the nano/molecular scales. [Copyright &y& Elsevier]

Highlights: [•] Al–Cu precipitation studied by simultaneous small- and wide-angle X-ray scattering. [•] Concurrent evolution of lattice phase, volume fractions and morphology revealed. [•] Phase transformation mechanism and structural evolution in precipitation sequence. [•] Concurrent existence of multiple precipitates in the precipitation sequence. [•] Evolutional behavior of the orientation and spatial distribution of precipitates. [ABSTRACT FROM AUTHOR]

Abstract: The microstructure of calcium–silicate–hydrate (C−S−H) gel, a major hydrated phase of Ordinary Portland Cement, with and without polycarboxylic ether (PCE) additives is investigated by combined analyses of small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) data. The results show that these comb-shaped polymers tend to increase the size of the disk-like globules but have little influence on the thickness of the water and calcium silicate layers within the globules. As a result, the fractal packing of the globules becomes more open in the range of a few hundred nanometers, in the sense that the mass fractal dimension diminishes, since the PCE adsorption on the globules increases the repulsive force between and polydispersity of the C−S−H units. Moreover, scanning electron microscope (SEM) study of the synthesized C−S−H gels in the micrometer range shows that the PCEs depress the formation of fibrils while enhancing the foil-like morphology. [Copyright &y& Elsevier]

Abstract: Nanostructured cobalt is one of the key elements in catalysis and therapeutic drug delivery. To design and prepare nanosize-controllable cobalt, a better understanding of its growth mechanism is essential. Growth of Co nanoparticles encapsulated in carbon-shell (Co@C) during temperature-programmed carbonization of the Co2+-β-cyclodextrin (CD) complex at 363–573K was, therefore, studied by in situ synchrotron small-angel X-ray scattering and X-ray absorption near edge structure spectroscopy. The carbon-shell having a thickness of about 2nm can prevent the core Co from being aggregated and oxidized. A relatively slow reduction of Co(II) to Co is observed at 393–423K (stage I) prior to a particle growth transition-state possessing Co of 2.2nm in diameter at 423–483K. At 483–513K (stage II), an increasing Co(II) reduction rate coupled with a rapid fusion and coalescence of Co nanoparticles is found. The average growth rates of Co at stages I and II are about 27 and 98 atoms/min, respectively. The most-probable particle diameter of the ripened Co is 5.9nm. The carbon-shell can be removed by steam reforming to yield the Co nanoparticles. This work also exemplifies the possible temperature-controllable growth of Co@C, especially in the Co size range of 2–6nm in diameter. [Copyright &y& Elsevier]

The crystallization kinetics and crystallization-inducedmorphologicalformation of an asymmetric double-crystalline block copolymer, syndiotacticpolypropylene-block-poly(ε-caprolactone) (sPP-b-PCL), have been investigated by time-resolved simultaneoussmall-angle and wide-angle X-ray scattering (SAXS/WAXS). The sPP-b-PCL under study exhibited hexagonally packed cylindermorphology in the melt state, where the minority sPP block formedthe cylindrical microdomains dispersed in the PCL matrix. The crystallizationbehavior was studied by imposing two types of crystallization histories:(1) two-stage crystallization, where the diblock was first cooledto the temperature TcsPPsituatingbetween the melting points of the two components (TmPCL< TcsPP< TmsPP) to allowsPP crystallization to saturation followed by cooling to TcPCL< TmPCLto induce PCL crystallization; (2) one-stage crystallization,where the system was cooled directly to Tc< TmPCLto allow the twocomponents to crystallize competitively. In both cases, the crystallizationof sPP block was in general able to disrupt the melt structure andtransformed it into a crystalline lamellar morphology. For the two-stagecrystallization process, the PCL block was found to exhibit a fastercrystallization at a given TcPCLwhen the sPP block was precrystallized at higher TcsPP. This “interactive crystallizationkinetics” was attributed to the mediation of the stretchingof PCL blocks by the thickness of sPP crystalline domains which dependedon TcsPP. In the one-stageprocess, the crystallization events of the two blocks became morecompetitive with decreasing Tc. The morphologicalperturbation induced by crystallization was also more hindered atlower Tc, such that a significant portionof sPP blocks remained confined within the cylindrical microdomainsso as to suppress the sPP crystallinity. [ABSTRACT FROM AUTHOR]

We have developed an improved small-angle X-ray scattering (SAXS) model and analysis methodology to quantitatively evaluate the nanostructures of a blend system. This method has been applied to resolve the various structures of self-organized poly(3-hexylthiophene) /C61-butyric acid methyl ester (P31-IT/PCBM) thin active layer in a solar cell from the studies of both grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence X-ray diffraction (GIXRID). Tuning the various length scales of PCBM-related structures by a different annealing process can provide a flexible approach and better understanding to enhance the power conversion of the P3HT/PCBM solar cell. The quantitative structural characterization by this method includes (1) the mean size, volume fraction, and size distribution of aggregated PCBM clusters, (2) the specific interface area between PCBM and P3HT, (3) the local cluster agglomeration, and (4) the correlation length of the PCBM molecular network within the P3HT phase. The above terms are correlated well with the device performance. The various structural evolutions and transformations (growth and dissolution) between PCBM and P3HT with the variation of annealing history are demonstrated here. This work established a useful SAXS approach to present insight into the modeling of the morphology of P3HT/PCBM film. In situ GISAXS measurements were also conducted to provide informative details of thermal behavior and temporal evolution of PCBM-related structures during phase separation. The results of this investigation significantly extend the current knowledge of the relationship of bulk heterojunction morphology to device performance. [ABSTRACT FROM AUTHOR]