The 24-chain core-shell nanostructure of wood cellulose microfibrils in seed plants

Wood cellulose microfibrils (CMFs) are the most abundant organic substance on earth, but their nanostructures are poorly understood. There are controversies regarding the glucan chain number (N) of CMFs during initial synthesis and whether they become fused afterwards. Here, we combined small-angle X-ray scattering (SAXS), solid-state nuclear magnetic resonance (ssNMR) and X-ray diffraction (XRD) analyses to resolve these controversies. We successfully developed SAXS measurement methods for the cross-section aspect ratio and area of the crystalline-ordered CMF core, which showed higher density than the semi-disordered shell. The 1:1 aspect ratio suggested that CMFs remain mostly segregated, not fused. The area measurement revealed the chain number in the core zone (Ncore). The ratio of ordered cellulose over total cellulose, termed Roc, was determined by ssNMR. Using the formula N = Ncore / Roc, we found that the majority of wood CMFs contain 24 chains, conserved between gymnosperm and angiosperm trees. The average wood CMF has a crystalline-ordered core of ~2.2 nm diameter and a semi-disordered shell of ~0.5 nm thickness. In naturally and artificially aged wood, we only observed CMF aggregation (contact without crystalline continuity) but not fusion (forming conjoined crystalline unit). This further argued against the existence of partially fused CMFs in new wood, overturning the recently proposed 18-chain fusion hypothesis. Our findings are important for advancing wood structural knowledge and more efficient utilization of wood resources in sustainable bio-economies.

Hierarchical Structure of Magnetic Nanoparticles -Fe3O4- Ferrofluids Revealed by Small Angle X-Ray Scattering

Small-angle X-ray scattering (SAXS) experiments were set up to investigate the form and structure of Fe3O4 magnetic nanoparticles (MNPs) using BL1.3:SAXS at the Synchrotron Light Research Institute (SLRI) of Thailand in the range of scattering vector q, 0.7 < q (nm–1) < 4. The scattering data from samples, background, and empty cells were collected and then subtracted using small-angle X-ray scattering image tool (SAXSIT) software. The analysis of the corrected scattering patterns for four different pH, i.e., 2, 3, 4, and 5, has been revealed by applying log-normal spherical and mass fractal models calculation. The results showed that the SAXS measurement could investigate the hierarchical structures of MNPs Fe3O4 containing primary and secondary particles. The two-dimensional fractal (Df) aggregates as secondary particles (in volume) have various sizes ranging from 21 to 103 nm in diameter, confirming the correlation to their pH. Those structures consist of primary particles with a mean length of 2 nm in radius and the particle size distribution (σ) of 0.5.

Facile Fabrication and Characterization of Improved Proton Conducting Sulfonated Poly(Arylene Biphenylether Sulfone) Blocks Containing Fluorinated Hydrophobic Units for Proton Exchange Membrane Fuel Cell Applications

Sulfonated poly(arylene biphenylether sulfone)-poly(arylene ether) (SPABES-PAE) block copolymers by controlling the molar ratio of SPABES and PAE oligomers were successfully synthesized, and the performances of SPABES-PAE (1:2, 1:1, and 2:1) membranes were compared with Nafion 212. The prepared membranes including fluorinated hydrophobic units were stable against heat, nucleophile attack, and physio-chemical durability during the tests. Moreover, the polymers exhibited better solubility in a variety of solvents. The chemical structure of SPABES-PAEs was investigated by 1H nuclear magnetic resonance (1H NMR), Fourier transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC). The membrane of SPABES-PAEs was fabricated by the solution casting method, and the membranes were very flexible and transparent with a thickness of 70–90 μm. The morphology of the membranes was observed using atomic force microscope and the ionic domain size was proved by small angle X-ray scattering (SAXS) measurement. The incorporation of polymers including fluorinated units allowed the membranes to provide unprecedented oxidative and dimensional stabilities, as verified from the results of ex situ durability tests and water uptake capacity, respectively. By the collective efforts, we observed an enhanced water retention capacity, reasonable dimensional stability and high proton conductivity, and the peak power density of the SPABES-PAE (2:1) was 333.29 mW·cm−2 at 60 °C under 100% relative humidity (RH).

In Situ SAXS Measurement and Molecular Dynamics Simulation of Magnetic Alignment of Hexagonal LLC Nanostructures

The alignment of nanostructures in materials such as lyotropic liquid crystal (LLC) templated materials has the potential to significantly improve their performances. However, accurately characterising and quantifying the alignment of such fine structures remains very challenging. In situ small angle X-ray scattering (SAXS) and molecular dynamics were employed for the first time to understand the hexagonal LLC alignment process with magnetic nanoparticles under a magnetic field. The enhanced alignment has been illustrated from the distribution of azimuthal intensity in the samples exposed to magnetic field. Molecular dynamics simulations reveal the relationship between the imposed force of the magnetic nanoparticles under magnetic field and the force transferred to the LLC cylinders which leads to the LLC alignment. The combinational study with experimental measurement and computational simulation will enable the development and control of nanostructures in novel materials for various applications.

In Situ SAXS Measurement and Molecular Dynamics Simulation of Magnetic Alignment of Hexagonal LLC Nanostructures

The alignment of nanostructures in materials such as lyotropic liquid crystals (LLCs) templated materials has the potential to signicantly improve their performances. However, accurately characterising and quantifying the alignement of such fine structures remains very challenging. In situ small angle X-ray scattering (SAXS) and molecular dynamics were employed for the first time to understand the hexagonal LLC alignment process with magnetic nanoparticles under a magnetic field. The enhanced alignment has been illustrated from the distribution of azimuthal intensity in the samples exposed to magnetic field. Molecular dynamics simulations reveal the relationship between the imposed force of the magenetic nanoparticles under magnetic field and the force transferred to the LLC cylinders which leads to the LLC alignment. The combinational study with experimental measurement and computational simulation will enable the development and control of nanostructures in novel materials for various applications.

Discotic liquid crystals of transition metal complexes 52: Synthesis and homeotropic alignment of liquid crystalline phthalocyanine-fullerene dyad bridged by vanillin

We have synthesized a novel liquid crystalline phthalocyanine(Pc)-fullerene(C[Formula: see text] dyad (C[Formula: see text]S)[Formula: see text]PcCu-VAN-C[Formula: see text] (3a) bridged by an inexpensive natural product of vanillin (VAN), instead of the previous long [Formula: see text]-alkylene chain spacer. We have also synthesized a comparative dyad (C[Formula: see text]S)[Formula: see text]PcCu-OPh-C[Formula: see text] (3b) bridged by [Formula: see text]-hydroxybenzaldehyde (OPh), in order to investigate the influence of the methoxy group in the vanillin moiety on homeotropic alignment between two glass plates. Very interestingly, homeotropic alignment could be observed only for the dyad (C[Formula: see text]S)[Formula: see text]PcCu-VAN-C[Formula: see text] (3a) having a methoxy group in the vanillin moiety, whereas it could not be observed for the dyad (C[Formula: see text]S)[Formula: see text]PcCu-OPh-C[Formula: see text] (3b) having no methoxy group at the phenoxy group. It is very noteworthy that such a slight difference in these molecular structures between 3a and 3b becomes a crucial point to show the homeotropic alignment. Each of the dyads, 3a and 3b, showed two hexagonal ordered columnar (Col[Formula: see text] mesophases. Each of the Col[Formula: see text] mesophases in 3a and 3b gave an additional very strong reflection peak named as Peak H in a very low angle region of the SAXS (small angle X-ray scattering) pattern. Peak H could be established, from two different SAXS measurement methods, as one pitch in a helical structure of the fullerenes around the Pc column.