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Lignin, an abundant, naturally occurring biopolymer, is often considered "waste" and used as a simple fuel source in the paper-making process. However, lignin has emerged as a promising renewable resource for engineering materials, such as carbon fibers. Unfortunately, the molecular architecture of lignin (in vivo and extracted) is still elusive, with numerous conflicting reports in the literature, and knowledge of this structure is extremely important, not only for materials technologies, but also for production of biofuels such as cellulosic ethanol due to biomass recalcitrance. As such, the molecular structures of solvent-extracted (sulfur-free) lignins, which have been modified using various acyl chlorides, have been probed using small-angle X-ray (SAXS) and neutron (SANS) scattering in tetrahydrofuran (THF) solution along with hydrodynamic characterization using dilute solution viscometry and gel permeation chromatography (GPC) in THF. Mass spectrometry shows an absolute molecular weight ≈18-30 kDa (≈80-140 monomers), while GPC shows a relative molecular weight ∼3 kDa. A linear styrene oligomer (2.5 kDa) was also analyzed in THF using SANS. Results clearly show that lignin molecular architectures are somewhat rigid and complex, ranging from nanogels to hyperbranched macromolecules, not linear oligomers or physical assemblies of oligomers, which is consistent with previously proposed delignification (extraction) mechanisms. Future characterization using the methods discussed here can be used to guide extraction processes as well as genetic engineering technologies to convert lignin into value added materials with the potential for high positive impact on global sustainability.

We used small-angle neutron scattering (SANS) and wide-angle X-ray scattering (WAXS) to study two Populus trichocarpa variants, GW-11012 and BESC-316, with lignin contents of 17.8 and 23.2%, respec...

A deep eutectic solvent (DES) entrapped in a bacterial cellulose (BC) network gives rise to a gelatin-like, self-supported material termed a bacterial cellulose eutectogel (BCEG). Although this novel material holds potential for numerous industrial, environmental, energy, or medical applications, little is known about the structural features or dynamical behavior within a eutectogel. In this work, we employ X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and small-angle neutron scattering (SANS) to probe the structural and diffusive behavior of the prevailing DES glyceline (1:2 molar ratio of choline chloride:glycerol) confined within bacterial cellulose. XRD investigations demonstrate that the bacterial cellulose maintains its crystallinity even as the glyceline content approaches 95 wt % in the BCEG, an outcome corroborated by molecular dynamics (MD) simulations, which suggest minimal changes in the structural features of the cellulose chains due to the presence of glyceline. SANS measurements reveal a significant reduction in the radius of gyration (Rg) for BC in a BCEG compared to its hydrogel analogue, indicating a collapse in the microfibrillar structure that we attribute to removal of waters from the interfibrillar space due to a higher affinity of DES for water than for cellulose. Furthermore, SANS experiments suggest that the vast majority of DES is hosted within large micropores in the BCEG (i.e., mesoscopic confinement). Interestingly, proton NMR experiments disclose faster diffusional rates for choline and glycerol entrapped in a BCEG compared to neat glyceline. MD simulations offer the possible explanation that this diffusional acceleration results from significant migration of chloride from the bulk to cellulose microfibrillar surfaces, thereby reducing hydrogen bonding with choline and glycerol partners. This study provides the first comprehensive investigation into the structure and diffusional dynamics of glyceline within a eutectogel, offering insights into mass transport that should be useful for tailoring these novel materials to potential applications.

Release of microplastics (MPs) and nanoplastics (NPs) into agricultural fields is of great concern due to their reported ecotoxicity to organisms that provide beneficial service to the soil such as earthworms, and the potential ability of MPs and NPs to enter the food chain. Most fundamental studies of the fate and transport of plastic particulates in terrestrial environments employ idealized MP materials as models, such as monodisperse polystyrene spheres. In contrast, plastics that reside in agricultural soils consist of polydisperse fragments resulting from degraded films employed in agriculture. There exists a need for more representative materials in fundamental studies of the fate, transport, and ecotoxicity of MPs and NPs in soil ecosystems. The objective of this study was therefore to develop a procedure to produce MPs and NPs from agricultural plastics (a mulch film prepared biodegradable polymer polybutyrate adipate-co-terephthalate (PBAT) and low-density PE [LDPE]), and to characterize the resultant materials. Soaking of PBAT films under cryogenic conditions promoted embrittlement, similar to what occurs through environmental weathering. LDPE and cryogenically-treated PBAT underwent mechanical milling followed by sieve fractionation into MP fractions of 840 μm, 250 μm, 106 μm, and 45 μm. The 106 μm fraction was subjected to wet grinding to produce NPs of average particle size 366.0 nm and 389.4 nm for PBAT and LDPE, respectively. A two-parameter Weibull model described the MPs' particle size distributions, while NPs possessed bimodal distributions. Size reduction did not produce any changes in the chemical properties of the plastics, except for slight depolymerization and an increase of crystallinity resulting from cryogenic treatment. This study suggests that MPs form from cutting and high-impact mechanical degradation as would occur during the tillage into soil, and that NPs form from the MP fragments in regions of relative weakness that possess lower molecular weight polymers and crystallinity.

Terrestrial nanoplastics (NPs) pose a serious threat to agricultural food production systems due to the potential harm of soil-born micro- and macroorganisms that promote soil fertility and ability of NPs to adsorb onto and penetrate into vegetables and other crops. Very little is known about the dispersion, fate and transport of NPs in soils. This is because of the challenges of analyzing terrestrial NPs by conventional microscopic techniques due to the low concentrations of NPs and absence of optical transparency in these systems. Herein, we investigate the potential utility of small-angle neutron scattering (SANS) and Ultra SANS (USANS) to probe the agglomeration behavior of NPs prepared from polybutyrate adipate terephthalate, a prominent biodegradable plastic used in agricultural mulching, in the presence of vermiculite, an artificial soil. SANS with the contrast matching technique was used to study the aggregation of NPs co-dispersed with vermiculite in aqueous media. We determined the contrast match point for vermiculite was 66% D2O / 33% H2O. At this condition, the signal for vermiculite was ~50-100%-fold lower that obtained using neat H2O or D2O as solvent. According to SANS and USANS, smaller-sized NPs (50 nm) remained dispersed in water and did not undergo size reduction or self-agglomeration, nor formed agglomerates with vermiculite. Larger-sized NPs (300-1000 nm) formed self-agglomerates and agglomerates with vermiculite, demonstrating their significant adhesion with soil. However, employment of convective transport (simulated by ex situ stirring of the slurries prior to SANS and USANS analyses) reduced the self-agglomeration, demonstrating weak NP-NP interactions. Convective transport also led to size reduction of the larger-sized NPs. Therefore, this study demonstrates the potential utility of SANS and USANS with contrast matching technique for investigating behavior of terrestrial NPs in complex soil systems.

Interactions of water with cellulose are of both fundamental and technological importance. Here, we characterize the properties of water associated with cellulose using deuterium labeling, neutron scattering and molecular dynamics simulation. Quasi-elastic neutron scattering provided quantitative details about the dynamical relaxation processes that occur and was supported by structural characterization using small-angle neutron scattering and X-ray diffraction. We can unambiguously detect two populations of water associated with cellulose. The first is “non-freezing bound” water that gradually becomes mobile with increasing temperature and can be related to surface water. The second population is consistent with confined water that abruptly becomes mobile at ~260 K, and can be attributed to water that accumulates in the narrow spaces between the microfibrils. Quantitative analysis of the QENS data showed that, at 250 K, the water diffusion coefficient was 0.85 ± 0.04 × 10−10 m2sec−1 and increased to 1.77 ± 0.09 × 10−10 m2sec−1 at 265 K. MD simulations are in excellent agreement with the experiments and support the interpretation that water associated with cellulose exists in two dynamical populations. Our results provide clarity to previous work investigating the states of bound water and provide a new approach for probing water interactions with lignocellulose materials.

Vesicle-templated nanocapsules are prepared by polymerization of hydrophobic acrylic monomers and cross-linkers in the hydrophobic interior of self-assembled bilayers. Understanding the mechanism of capsule formation and the influence of synthetic parameters on the structural features and functional performance of nanocapsules is critical for the rational design of functional nanodevices, an emerging trend of application of the nanocapsule platform. This study investigated the relationship between basic parameters of the formulation and synthesis of nanocapsules and structural and functional characteristics of the resulting structures. Variations in the monomer/surfactant ratio, temperature of polymerization, and the molar fraction of the free-radical initiators were investigated with a multipronged approach, including shell thickness measurements using small-angle neutron scattering, evaluation of the structural integrity of nanocapsules with scanning electron microscopy, and determination of the retention of entrapped molecules using absorbance and fluorescence spectroscopy. Surprisingly, the thickness of the shells did not correlate with the monomer/surfactant ratio, supporting the hypothesis of substantial stabilization of the surfactant bilayer with loaded monomers. Decreasing the temperature of polymerization had no effect on the spherical structure of nanocapsules but resulted in progressively lower retention of entrapped molecules, suggesting that a spherical skeleton of nanocapsule forms rapidly, followed by filling the gaps to create the structure without pinholes. Lower content of initiators resulted in slower reactions, outlining the baseline conditions for practical synthetic protocols. Taken together, these findings provide insights into the formation of nanocapsules and offer methods for controlling the properties of nanocapsules in viable synthetic methods.

Biofuels produced from lignocellulosic biomass hold great promise as a renewable alternative energy and fuel source. To realize a cost and energy efficient approach, a fundamental understanding of the deconstruction process is critically necessary to reduce biomass recalcitrance. Herein, the structural and morphological changes over multiple scales (5–6000 A) in herbaceous (switchgrass) and woody (hybrid poplar) biomass during dilute sulfuric acid pretreatment were explored using neutron scattering and X-ray diffraction. Switchgrass undergoes a larger increase (20–84 A) in the average diameter of the crystalline core of the elementary cellulose fibril than hybrid poplar (19–50 A). Switchgrass initially forms lignin aggregates with an average size of 90 A that coalesce to 200 A, which is double that observed for hybrid poplar, 55–130 A. Switchgrass shows a smooth-to-rough transition in the cell wall surface morphology unlike the diffuse-to-smooth transition of hybrid poplar. Yet, switchgrass and hybrid pop...

A better understanding of how wood nanostructure swells with moisture is needed to accelerate the development of forest products with enhanced moisture durability. Despite its suitability to study nanostructures, small angle neutron scattering (SANS) remains an underutilized tool in forest products research. Nanoscale moisture-induced structural changes in intact and partially cut wood cell walls were investigated using SANS and a custom-built relative humidity (RH) chamber. SANS from intact wood sections cut from each primary wood orientation showed that although wood scattered anisotropically across 1.3–600 nm length scales, measurement of elementary fibril spacing and low-q surface scattering were independent of orientation. Water sorption caused spacing between elementary fibrils to increase with RH, and this swelling accounted for over half the transverse swelling in S2 secondary wood cell walls. Elementary fibril spacing in longitudinally cut wood cells, which were designed to mimic cells near wood-adhesive bondlines, was greater than the spacing in intact cells above 90 % RH. This suggested that some cell wall hoop constraint from the S1 and S3 cell wall layers on the S2 layer was released by cutting the cells. Furthermore, increased spacing between elementary fibrils may also create diffusion channels that are hypothesized to be responsible for the onset of fungal decay in wood. Protocols were established to use SANS in future research to study adhesives and protection treatments to improve moisture durability in forest products.

The biological small-angle neutron scattering instrument at the High-Flux Isotope Reactor of Oak Ridge National Laboratory is dedicated to the investigation of biological materials, biofuel processing, and bio-inspired materials covering nanometer to micrometer length scales. The methods presented here for investigating physical properties (i.e., size and shape) of membrane proteins (here, MmIAP, an intramembrane aspartyl protease from Methanoculleus marisnigri) in solutions of micelle-forming detergents are well-suited for this small-angle neutron scattering instrument, among others. Other biophysical characterization techniques are hindered by their inability to address the detergent contributions in a protein-detergent complex structure. Additionally, access to the Bio-Deuteration Lab provides unique capabilities for preparing large-scale cultivations and expressing deuterium-labeled proteins for enhanced scattering signal from the protein. While this technique does not provide structural details at high-resolution, the structural knowledge gap for membrane proteins contains many addressable areas of research without requiring near-atomic resolution. For example, these areas include determination of oligomeric states, complex formation, conformational changes during perturbation, and folding/unfolding events. These investigations can be readily accomplished through applications of this method.

We demonstrate here for the first time via small-angle neutron scattering (SANS) that the middle, bicontinuous microemulsion (BμE) phase of Winsor-III systems undergoes a gradual change of structure and composition in the vertical direction, contrary to the commonly held belief of uniform structure and composition. A vertical stage was deployed to enable precise alignment of a custom-designed rectangular cell containing the WIII system with respect to the neutron beam, allowing for several different vertical positions to be analyzed. For the water/AOT/CK-2,13 (two-tailed alkyl ethoxylate containing a 1,3-dioxolane linkage)/heptane Winsor-III system, the quasi-periodic repeat distance (d) and correlation length (ξ), obtained from the Teubner–Strey model applied to the SANS data, decreased and the surface area per volume of the surfactant monolayer (via Porod analysis) increased in the downward direction, trends that reflect an increase of surfactant concentration, consistent with the ultralow interfacial tension that often occurs for the lower liquid–liquid interface of many WIII systems. The water/sodium dodecyl sulfate (SDS)/1-pentanol/dodecane system shared the same trend with regard to d as observed for AOT/CK-2,13. In contrast, for SDS/pentanol, ξ increased and the amphiphilicity factor (fa) decreased in the downward direction, trends consistent with a decrease of cosurfactant (pentanol) concentration in the downward direction. Non-uniformity in the vertical direction has implications in the transport of solutes between WIII phases during the extractive purification of proteins or the removal of heavy metals and pollutants from wastewater, or the deposition of BμEs onto hydrophilic vs. hydrophobic surfaces as thin coatings.

Mamontov, Eugene/0000-0002-5684-2675; Smith, Micholas Dean/0000-0002-0777-7539; smith, jeremy c/0000-0002-2978-3227; Parks, Jerry M./0000-0002-3103-9333; Ragauskas, Art/0000-0002-3536-554X; VURAL, DERYA/0000-0002-0120-3024; Sokolov, Alexei/0000-0002-8187-9445; Gainaru, Catalin/0000-0001-8295-6433 WOS: 000432567300021 The full utilization of plant biomass for the production of energy and novel materials often involves high temperature treatment. Examples include melt spinning of lignin for manufacturing low-cost carbon fiber and the relocalization of lignin to increase the accessibility of cellulose for production of biofuels. These temperature-induced effects arise from poorly understood changes in lignin flexibility. Here, we combine molecular dynamics simulations with neutron scattering and dielectric spectroscopy experiments to probe the dependence of lignin dynamics on hydration and thermal history. We find a dynamical and structural hysteresis: at a given temperature, the lignin molecules are more expanded and their dynamics faster when the lignin is cooled than when heated. The structural hysteresis is more pronounced for dry lignin. The difference in dynamics, however, follows a different trend, it is found to be more significant at high temperatures and high hydration levels. The simulations also reveal syringyl units to be more dynamic than guiacyl. The results provide an atomic-detailed description of lignin dynamics, important for understanding lignin role in plant cell wall mechanics and for rationally improving lignin processing. The lignin glass transition, at which the polymer softens, is lower when lignin is cooled than when heated; therefore extending the cooling phase of processing and shortening the heating phase may offer ways to lower processing costs. Genomic Science Program, Office of Biological and Environmental Research, U. S. Department of Energy (DOE) [FWP ERKP752]; Office of Science of the U. S. Department of EnergyUnited States Department of Energy (DOE) [DE-AC02-05CH11231]; DOEUnited States Department of Energy (DOE) [DE-AC05-00OR22725]; DOE Office of Science, BES Materials Sciences and Engineering Division This research was supported by the Genomic Science Program, Office of Biological and Environmental Research, U. S. Department of Energy (DOE), under Contract FWP ERKP752. CG and APS acknowledge support by the DOE Office of Science, BES Materials Sciences and Engineering Division for the dielectric studies. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for DOE under Contract DE-AC05-00OR22725.

Vesicle-templated nanocapsules have emerged as a viable platform for diverse applications. Shell thickness is a critical structural parameter of nanocapsules, where the shell plays a crucial role providing mechanical stability and control of permeability. Here we used small-angle neutron scattering (SANS) to determine the thickness of freestanding and surfactant-stabilized nanocapsules. Despite being at the edge of detectability, we were able to show the polymer shell thickness to be typically 1.0 ± 0.1 nm, which places vesicle-templated nanocapsules among the thinnest materials ever created. The extreme thinness of the shells has implications for several areas: mass-transport through nanopores is relatively unimpeded; pore-forming molecules are not limited to those spanning the entire bilayer; the internal volume of the capsules is maximized; and insight has been gained on how polymerization occurs in the confined geometry of a bilayer scaffold, being predominantly located at the phase-separated layer of monomers and cross-linkers between the surfactant leaflets.

One commonly cited factor that contributes to the recalcitrance of biomass is cellulose crystallinity. The present study aims to establish the effect of several pretreatment technologies on cellulose crystallinity, crystalline allomorph distribution, and cellulose ultrastructure. The observed changes in the cellulose ultrastructure of poplar were also related to changes in enzymatic hydrolysis, a measure of biomass recalcitrance. Hot-water, organo-solv, lime, lime-oxidant, dilute acid, and dilute acid-oxidant pretreatments were compared in terms of changes in enzymatic sugar release and then changes in cellulose ultrastructure measured by 13C cross polarization magic angle spinning nuclear magnetic resonance and wide-angle X-ray diffraction. Pretreatment severity and relative chemical depolymerization/degradation were assessed through compositional analysis and high-performance anion-exchange chromatography with pulsed amperometric detection. Results showed minimal cellulose ultrastructural changes occurred due to lime and lime-oxidant pretreatments, which at short residence time displayed relatively high enzymatic glucose yield. Hot water pretreatment moderately changed cellulose crystallinity and crystalline allomorph distribution, yet produced the lowest enzymatic glucose yield. Dilute acid and dilute acid-oxidant pretreatments resulted in the largest increase in cellulose crystallinity, para-crystalline, and cellulose-Iβ allomorph content as well as the largest increase in cellulose microfibril or crystallite size. Perhaps related, compositional analysis and Klason lignin contents for samples that underwent dilute acid and dilute acid-oxidant pretreatments indicated the most significant polysaccharide depolymerization/degradation also ensued. Organo-solv pretreatment generated the highest glucose yield, which was accompanied by the most significant increase in cellulose microfibril or crystallite size and decrease in relatively lignin contents. Hot-water, dilute acid, dilute acid-oxidant, and organo-solv pretreatments all showed evidence of cellulose microfibril coalescence.

Neutron scattering is a powerful technique that can be used to probe the structures and dynamics of complex systems. It can provide a fundamental understanding of the processes involved in the production of biofuels from lignocellulosic biomass. A variety of neutron scattering technologies are available to elucidate both the organization and deconstruction of this complex composite material and the associations and morphology of the component polymers and the enzymes acting on them, across multiple length scales ranging from Angstroms to micrometers and time scales from microseconds to picoseconds. Unlike most other experimental techniques, neutron scattering is uniquely sensitive to hydrogen (and its isotope deuterium), an atom abundantly present throughout biomass and a key effector in many biological, chemical, and industrial processes for producing biofuels. Sensitivity to hydrogen, the ability to replace hydrogen with deuterium to alter scattering levels, the fact that neutrons cause little ...

Cross-linked polystyrene nanodisks were prepared by controlled polymerization of styrene and divinylbenzene in the interior of bicelles, discoidal lipid aggregates. Aggregation behavior of polymer nanodisks was studied in water, organic solvents, and solid phase. Nanodisks form stable dispersions in aqueous solutions of surfactants, such as sodium dodecyl sulfate (SDS). Varying SDS/nanodisk ratio allowed us to control the size of nanodisk aggregates. Nanodisks are readily solubilized in nonpolar organic solvents, such as toluene and carbon tetrachloride, to yield stable monodisperse suspensions. These findings open opportunities for creating nanodisk-based nanocomposite materials. Stable nanodisk suspension in toluene enabled small angle neutron scattering (SANS) measurements. SANS data confirmed the nanodisk diameter and allowed accurate measurement of nanodisk thickness (19.5 ± 1.0 A). In solid phase, nanodisks aggregate in sub-micron platelets.

One-dimensional (1D) polyaniline/tobacco mosaic virus (TMV) composite nanofibers and macroscopic bundles of such fibers were generated via a self-assembly process of TMV assisted by in-situ polymerization of polyaniline on the surface of TMV. At near-neutral reaction pH, branched polyaniline formed on the surface of TMV preventing lateral association. Therefore, long 1D nanofibers were observed with high aspect ratios and excellent processibility. At a lower pH, transmission electron microscopy (TEM) analysis revealed that initially long nanofibers were formed which resulted in bundled structures upon long-time reaction, presumably mediated by the hydrophobic interaction because of the polyaniline on the surface of TMV. In-situ time-resolved small-angle X-ray scattering study of TMV at different reaction conditions supported this mechanism. This novel strategy to assemble TMV into 1D and 3D supramolecular composites could be utilized in the fabrication of advanced materials for potential applications including electronics, optics, sensing, and biomedical engineering.

Fluorocarbon films were grown on polystyrene in vacuum from 25- to 100-eV mass-selected C3F5+ ion beams. The films were analyzed by X-ray photoelectron spectroscopy, atomic force microscopy, and X-ray reflectivity after exposure to the atmosphere for 4−8 weeks. The X-ray reflectivity indicates films that range from ∼30 to 60-A thick. The thinner films form at lower ion energies, where the ion penetration depth and efficiency of film formation are lowest. X-ray reflectivity estimates air−fluorocarbon film roughness values of ∼6 A for 25- and 50-eV films but ∼20 A for the 100-eV films. The fluorocarbon−polystyrene-buried interface displays similar roughness and trends with ion energy. The AFM roughness trends are similar, but the absolute AFM roughnesses are only ∼1/4 of the X-ray reflectivity values. This discrepancy is attributed to tip effects and the method of determining roughness by AFM. The AFM images and power spectral densities of the 100-eV films displayed quasi-periodic cones spaced 300−700 A apa...

Morphological changes to the different components of lignocellulosic biomass were observed as they occurred during steam pretreatment by placing a pressure reaction cell in a neutron beam and collecting time-resolved neutron scattering data. Changes to cellulose morphology occurred mainly in the heating phase, whereas changes in lignin morphology occurred mainly in the holding and cooling phases. During the heating stage, water is irreversibly expelled from cellulose microfibrils as the elementary fibrils coalesce. During the holding phase lignin aggregates begin to appear and they increase in size most noticeably during the cooling phase. This experiment demonstrates the unique information that in situ small angle neutron scattering studies of pretreatment can provide. This approach could be useful in optimizing the heating, holding and cooling stages of pretreatments to allow the exact size and nature of lignin aggregates to be controlled in order to enhance enzyme accessibility to cellulose and therefore the efficiency of biomass conversion.

Structural changes across multiple length scales associated with hydrothermal pretreatments of biomass were investigated by using small- and wide-angle X-ray and neutron scattering on oriented specimens. Isotropic and anisotropic scattering components were numerically separated and then interpreted as contributions from matrix and cellulose components, respectively. Equatorial diffraction peaks present in the isotropic component became sharper after hydrothermal treatments or ammonia treatment. Before pretreatment the wet cell wall was found to be homogeneous in the 10–100 nm range and scattering below Q = 0.5 (nm−1) was dominated by surface scattering from the lumen. After pretreatment with acid or steam at 160 or 180 °C, density fluctuation developed in the cell wall at length scales above 10 nm, most likely due to lateral coalescence of microfibrils that partially co-crystallize to give larger apparent crystal sizes. A density fluctuation up to about 100 nm appeared in the isotropic component after acid and steam pretreatments due to morphological changes in the hemicellulose and lignin matrix.

Surfactant vesicles containing monomers in the interior of the bilayer were used to template hollow polymer nanocapsules. This study investigated the formation of surfactant/monomer assemblies by two loading methods, concurrent loading and diffusion loading. The assembly process and the resulting aggregates were investigated with dynamic light scattering, small angle neutron scattering, and small-angle X-ray scattering. Acrylic monomers formed vesicles with a mixture of cationic and anionic surfactants in a broad range of surfactant ratios. Regions with predominant formation of vesicles were broader for compositions containing acrylic monomers compared with blank surfactants. This observation supports the stabilization of the vesicular structure by acrylic monomers. Diffusion loading produced monomer-loaded vesicles unless vesicles were composed from surfactants at the ratios close to the boundary of a vesicular phase region on a phase diagram. Both concurrent-loaded and diffusion-loaded surfactant/monomer vesicles produced hollow polymer nanocapsules upon the polymerization of monomers in the bilayer followed by removal of surfactant scaffolds.

Lignin, a major polymeric component of plant cell walls, forms aggregates in vivo and poses a barrier to cellulosic ethanol production. Here, neutron scattering experiments and molecular dynamics simulations reveal that lignin aggregates are characterized by a surface fractal dimension that is invariant under change of scale from $~$1--1000 \AA{}. The simulations also reveal extensive water penetration of the aggregates and heterogeneous chain dynamics corresponding to a rigid core with a fluid surface.

An extensive study of the factors that affect the interfacial assembly of bionanoparticles at the oil/water (O/W) interface is reported. Bionanoparticles, such as viruses, have distinctive structural properties due to the unique arrangement of their protein structures. The assembly process of such bionanoparticles at interfaces is governed by factors including the ionic strength and pH of the aqueous layer, concentration of the particles, and nature of the oil phase. This study highlights the impact of these factors on the interfacial assembly of bionanoparticles at the O/W interface using native turnip yellow mosaic virus (TYMV) as the prototype. Robust monolayer assemblies of TYMV were produced by self-assembly at the O/W interface using emulsions and planar interfaces. TYMV maintained its structure and integrity under different assembly conditions. For the emulsion droplets, they were fully covered with TYMV as evidenced by transmission electron microscopy (TEM) and scanning force microscopy (SFM). Tensiometry and small-angle neutron scattering (SANS) further supported this finding. Although the emulsions offered a complete coverage by TYMV particles, they lacked long-range ordering due to rapid exchange at the interface. By altering the assembly process, highly ordered, hexagonal arrays of TYMV were obtained at planar O/W interfaces. The pH, ionic strength, and viscosity of the solution played a crucial role in enhancing the lateral ordering of TYMV assembled at the planar O/W interface. This interfacial ordering of TYMV particles was further stabilized by introduction of a positively charged dehydroabietyl amine (DHAA) in the organic phase which held the assembly together by electrostatic interactions. The long-range array formation was observed using TEM and SFM. The results presented here illustrate that the interfacial assembly at the O/W interface is a versatile approach to achieve highly stable self-assembled structures.

International audience; Transparent wood biocomposites based on PMMA combine high optical transmittance with excellent mechanical properties. One hypothesis is that despite poor miscibility the polymer is distributed at the nanoscale inside the cell wall. Smallangle neutron scattering (SANS) experiments are performed to test this hypothesis, using biocomposites based on deuterated PMMA and "contrast-matched" PMMA. The wood cell wall nanostructure soaked in heavy water is quantified in terms of the correlation distance d between the center of elementary cellulose fibrils. For wood/ deuterated PMMA, this distance d is very similar as for wood/ heavy water (correlation peaks at q ≈ 0.1 Å −1). The peak disappears when contrast-matched PMMA is used, indeed proving nanoscale polymer distribution in the cell wall. The specific processing method used for transparent wood explains the nanocomposite nature of the wood cell wall and can serve as a nanotechnology for cell wall impregnation of polymers in large wood biocomposite structures.

Small-Angle Neutron Scattering (SANS) is well-suited to study structure and function of protein in solution by exploiting the natural scattering contrast difference between proteins and other biomolecules such as lipids and nucleic acids. The combination of high neutron flux and low experimental background makes the Bio-SANS instrument at ORNL's High Flux Isotope Reactor (HFIR) an ideal tool to study proteins and other biomolecules within complex biological assemblies and composites, in situ and in-vivo. The procedures used for protein solution scattering at the Bio-SANS are presented here. The scattering signal is collected by a newly-developed Linear Position-Sensitive Detector (LPSD), which has a count rate capability of at least one million neutrons per second. It enables the Bio-SANS to utilize the full potential of the intense cold neutron source at HFIR. The detector-to-sample distance is adjustable from ∼1m to ∼15.3m to provide q-range from 0.0009 1/A to 0.7 1/A. The data collected at different distances are corrected against dark current, pixel efficiency, sample transmission and geometry to produce 1D profiles to be merged into a full scattering data set. A calibrated standard sample or direct beam intensity is used to obtain the absolutely scaled intensity of protein scattering. A few examples are presented here to demonstrate the procedure and the capability. They include scattering from protein crowded by another protein, membrane protein in a membrane-mimic environment, etc.