Structure Of Soft Materials Research Articles

Hierarchical Structure of Soft Materials Studied at Small-Angle Neutron Scattering Instrument, SANS-U

Hierarchical Structure of Soft Materials Studied at Small-Angle Neutron Scattering Instrument, SANS-U

MULTIFRACTAL ANALYSIS OF POLARIZATION MAPS OF ELLIPTICITY OF MICROSCOPIC IMAGES OF BLOOD SMEARS AND DIFFERENTIAL DIAGNOSIS OF THYROID GLAND PATHOLOGY

Among the numerous biomedical diagnostic applications of the soft matter structure,Mueller- matrix polarimetry of the optical anisotropy of biological tissues occupies animportant place. Various Mueller- matrix polarimetry systems have been developed toimplement the diagnostic tasks.The aim of the study – to conduct a comparative analysis of the effectiveness of themultifractal processing method of polarization ellipticity maps of digital microscopicimages of supramolecular protein networks of polycrystalline blood smears in orderto determine new objective criteria (markers) of digital laser histological differentialdiagnosis of the thyroid gland pathology.Material and methods. Four observation groups were formed: 1. Control group – healthydonors (51 people). 2. Patients with nodular goiter (51 patients). 3. Patients with autoimmunethyroiditis (51 patients). 4. Patients with papillary cancer (51 patients). A comparative analysisof the effectiveness of the statistical and multifractal processing methods of polarizationellipticity maps of digital microscopic images of supramolecular protein networks ofpolycrystalline blood smears was carried out in order to determine new objective criteria(markers) of digital laser histological differential diagnosis of the thyroid pathology. Results. A comprehensive statistical and multifractal analysis of polarization ellipticitymaps of experimental blood samples of donors and patients with nodular goiter,autoimmune thyroiditis, and papillary cancer was performed. Objective statistical andmultifractal markers for differential diagnosis of the thyroid gland pathology weredetermined. An excellent level (~96 %-98 %) of the balanced accuracy of the multifractalanalysis method of polarization maps of blood for minimally invasive differentiation ofpathological conditions has been demonstrated.Conclusions. 1. The most optimal statistical markers of the method of mapping ellipticitymaps of polarization of digital microscopic images of blood smears were found to bethe most optimal, and a good diagnostic capacity of diagnosis (~87.3 %-88.3 %) anda satisfactory level (~78.4 %-81.4 %) of differentiation of thyroid pathology wereestablished. 2. Multifractal markers of the mapping ellipticity maps method of polarizationof digital microscopic images of blood smears were found to be the most optimal and anexcellent level (~96 %-98 %) of the balanced accuracy of differential diagnosis of thethyroid gland pathologies was established.

Visualizing the Heterogeneity in Homogeneous Supramolecular Polymers.

The dynamic properties of supramolecular polymers enable new functionality beyond the limitations of conventional polymers. The mechanism of the monomer exchange between different supramolecular polymers is proposed to be closely associated with local disordered domains within the supramolecular polymers. However, a direct detection of such heterogeneity has never been experimentally probed. Here, we present the direct visualization of the local disordered domains in the backbone of supramolecular polymers by a super-resolution microscopy technique: Nile Red-based spectrally resolved point accumulation for imaging in nanoscale topography (NR-sPAINT). We investigate the local disordered domains in trisamide-based supramolecular polymers comprising a (co)assembly of benzene-1,3,5-tricarboxamide (BTA) and a variant with one of the amide bonds inverted (iBTA). The NR-sPAINT allows us to simultaneously map the spatial distribution and polarity of the local disordered domains along the polymers with a spatial precision down to ∼20 nm. Quantitative autocorrelation and cross-correlation analysis show subtle differences in the spatial distribution of the disordered domains between polymers composed of different variants of BTA monomers. Further, statistical analysis unraveled high heterogeneity in monomer packing at both intra- and interpolymer levels. The results reported here demonstrate the necessity of investigating the structures in soft materials at nanoscale to fully understand their intricacy.

Real-Space Visualization of Charged Polymer Network of Hydrogel by Double Network Strategy and Mineral Staining.

Hydrogels consist of three-dimensional (3D) and complicated polymer networks that determine their physical properties. Among the methods for structural analyses of hydrogels, the real-space imaging of a polymer network of hydrogels on a nanometer scale is one of the optimal methods; however, it is highly challenging. In this study, we propose a direct observation method for cationic polymer networks using transmission electron microscopy (TEM). By combining the double network strategy and the mineral staining technique, we overcame the challenges of polymer aggregation and the low electron density of the polymer. An objective cationic network was incorporated into a neutral skeleton network to suppress shrinkage during subsequent staining. Titania mineralization along the cationic polymer strands provided sufficient electron density for the objective polymer network for TEM observation. This observation method enables the visualization of local structures in real space and plays a complementary role to scattering methods for soft matter structure analysis.

Inferring effective electrostatic interaction of charge-stabilized colloids from scattering using deep learning

An innovative strategy is presented that incorporates deep auto-encoder networks into a least-squares fitting framework to address the potential inversion problem in small-angle scattering. To evaluate the performance of the proposed approach, a detailed case study focusing on charged colloidal suspensions was carried out. The results clearly indicate that a deep learning solution offers a reliable and quantitative method for studying molecular interactions. The approach surpasses existing deterministic approaches with respect to both numerical accuracy and computational efficiency. Overall, this work demonstrates the potential of deep learning techniques in tackling complex problems in soft-matter structures and beyond.

Strain to shine: stretching-induced three-dimensional symmetries in nanoparticle-assembled photonic crystals

Stretching elastic materials containing nanoparticle lattices is common in research and industrial settings, yet our knowledge of the deformation process remains limited. Understanding how such lattices reconfigure is critically important, as changes in microstructure lead to significant alterations in their performance. This understanding has been extremely difficult to achieve due to a lack of fundamental rules governing the rearrangements. Our study elucidates the physical processes and underlying mechanisms of three-dimensional lattice transformations in a polymeric photonic crystal from 0% to over 200% strain during uniaxial stretching. Corroborated by comprehensive experimental characterizations, we present analytical models that precisely predict both the three-dimensional lattice structures and the macroscale deformations throughout the stretching process. These models reveal how the nanoparticle lattice and matrix polymer jointly determine the resultant structures, which breaks the original structural symmetry and profoundly changes the dispersion of photonic bandgaps. Stretching induces shifting of the main pseudogap structure out from the 1st Brillouin zone and the merging of different symmetry points. Evolutions of multiple photonic bandgaps reveal potential optical singularities shifting with strain. This work sets a new benchmark for the reconfiguration of soft material structures and may lay the groundwork for the study of stretchable three-dimensional topological photonic crystals.

Hierarchical Self-Assembly of Water-Soluble Fullerene Derivatives into Supramolecular Hydrogels.

Controlling the self-assembly of nanoparticle building blocks into macroscale soft matter structures is an open question and of fundamental importance to fields as diverse as nanomedicine and next-generation energy storage. Within the vast library of nanoparticles, the fullerenes-a family of quasi-spherical carbon allotropes-are not explored beyond the most common, C60. Herein, a facile one-pot method is demonstrated for functionalizing fullerenes of different sizes (C60, C70, C84, and C90-92), yielding derivatives that self-assemble in aqueous solution into supramolecular hydrogels with distinct hierarchical structures. It is shown that the mechanical properties of these resultant structures vary drastically depending on the starting material. This work opens new avenues in the search for control of macroscale soft matter structures through tuning of nanoscale building blocks.

On inherent hyperelastic crease

We present analyses of the inherent hyperelastic crease that entails an unstable degenerative singular perturbation field over a uniformly compressed hyperelastic half-space. The analyses reveal asymptotic far-field characteristics of the singular field that bring out admissible incremental elastic deformation mechanisms of the inherent creasing instability typically observed at a compressive strain of ∼0.354 in neo-Hookean solids. The admissible singular perturbation field has an asymptotic leading-order incremental-stress singularity decaying 1/r2 as the distance from the crease tip r→∞. In general, asymptotic incremental-deformation fields of 1/r2 stress singularity can be introduced by surface flaws. We found that the singular field creates a far-field eigenmode of three energy-release angular sectors separated by two energy-elevating sectors of incremental deformation. The far-field eigenmode braces the near-tip energy-release field of the surface flaw against the transition to an unstable self-similar expansion field of creasing. Two asymptotic far-field parameters can characterize the braced-incremental-deformation (bid) and crease fields. One is the Burgers vector of a projected subsurface dislocation of the asymptotically singular far field. The other is a dimensionless shape factor representing the ratio of the subsurface depth of the dislocation to the Burgers vector. Our analyses show that the shape factor gauges the transition from the stable bid field to the unstable inherent crease field at the crease limit point as the compression increases. Two tangential-manifold conservation integrals are revealed to identify the two parameters. At the crease-limit point, matched asymptotes lead to the ratio between the two separate scaling parameters of the asymptotic solutions of the crease-tip folding field and the leading-order far field. To this end, we introduced a novel finite element method (FEM) for simulating the crease field nearly in a hyperelastic half-space with a finite-size simulation domain. Furthermore, we uncovered with the Gent model (1996) that strain-stiffening in hyperelasticity alters the dependence of the shape factor on the compressive strain, raising crease resistance. The new findings in hyperelastic crease mechanisms will help study ruga mechanics of self-organization and design soft-material structures and skin conditions for high crease resistance.

Local Structural Features Elucidate Crystallization of Complex Structures.

Complex crystal structures are composed of multiple local environments, and how this type of order emerges spontaneously during crystal growth has yet to be fully understood. We study crystal growth across various structures and along different crystallization pathways, using self-assembly simulations of identical particles that interact via multiwell isotropic pair potentials. We apply an unsupervised machine learning method to features from bond-orientational order metrics to identify different local motifs present during a given structure's crystallization process. In this manner, we distinguish different crystallographic sites in highly complex structures. Tailoring this order parameter to structures of varying complexity and coordination number, we study the emergence of local order along a multistep crystal growth pathway─from a low-density fluid to a high-density, supercooled amorphous liquid droplet and to a bulk crystal. We find a consistent under-coordination of the liquid relative to the average coordination number in the bulk crystal. We use our order parameter to analyze the geometrically frustrated growth of a Frank-Kasper phase and discover how structural defects compete with the formation of crystallographic sites that are more high-coordinated than the liquid environments. The method presented here for classifying order on a particle-by-particle level has broad applicability to future studies of structural self-assembly and crystal growth, and they can aid in the design of building blocks and for targeting pathways of formation of soft-matter structures.

Noether invariance theory for the equilibrium force structure of soft matter

We give details and derivations for the Noether invariance theory that characterizes the spatial equilibrium structure of inhomogeneous classical many-body systems, as recently proposed and investigated for bulk systems (Sammüller et al 2023 Phys. Rev. Lett. 130 268203). Thereby an intrinsic thermal symmetry against a local shifting transformation on phase space is exploited on the basis of the Noether theorem for invariant variations. We consider the consequences of the shifting that emerge at second order in the displacement field that parameterizes the transformation. In a natural way the standard two-body density distribution is generated. Its second spatial derivative is thereby balanced by two further and different two-body correlation functions, which respectively introduce thermally averaged force correlations and force gradients in a systematic and microscopically sharp way into the framework. Separate exact self and distinct sum rules express this balance. We exemplify the validity of the theory on the basis of computer simulations for the Lennard–Jones gas, liquid, and crystal, the Weeks–Chandler–Andersen fluid, monatomic Molinero–Moore water at ambient conditions, a three-body-interacting colloidal gel former, the Yukawa and soft-sphere dipolar fluids, and for isotropic and nematic phases of Gay–Berne particles. We describe explicitly the derivation of the sum rules based on Noether’s theorem and also give more elementary proofs based on partial phase space integration following Yvon’s theorem.

Characterization of a Rectangular-Cut Kirigami Pattern for Soft Material Tuning

Kirigami is the art of cutting paper to create three-dimensional figures for primarily aesthetic purposes. However, it can also modify the mechanical behavior of the resulting structure. In the literature, kirigami has been applied to modify the material’s structural behavior, such as by changing its elasticity, rigidity, volume, or any other characteristic. This article examines the behavior of a pattern of rectangular kirigami cuts on a thermoplastic polyurethane soft material structure and its influence on the mechanical parameters of the macrostructure. The results demonstrate that rectangular kirigami patterns significantly affect the stiffness of the test specimens, changing from 1635 N/m to 4020 N/m. In elongation, there is a variation from 176.6% to 218% by simply altering the height of the rectangular cut. This enables the adjustment of the soft material structure’s stiffness based on the geometry of the propagating kirigami cuts.

Stability Enhancement in All-Inorganic Perovskite Light Emitting Diodes via Dual Encapsulation.

Addressing the challenge of lighting stability in perovskite white light emitting diodes (WLEDs) is crucial for their commercial viability. CsPbX3 (X = Cl, Br, I, or mixed) nanocrystals (NCs) are promising for next-generation lighting due to their superior optical and electronic properties. However, the inherent soft material structure of CsPbX3 NCs is particularly susceptible to the elevated temperatures associated with prolonged WLED operation. Additionally, these NCs face stability challenges in high humidity environments, leading to reduced lighting performance. This study introduces a two-step dual encapsulation method, resulting in CsPbBr3@SiO2/Al2SiO5 composite fibers (CFs) with enhanced optical stability under extreme conditions. In testing, WLEDs incorporating these CFs, even under prolonged operation at high power (100mA for 9 h), maintain consistent electroluminescence (EL) intensity and optoelectronic parameters, with surface temperatures reaching 84.2 °C. Crucially, when subjected to 85 °C and 85% relative humidity for 200 h, the WLEDs preserve 97% of their initial fluorescence efficiency. These findings underscore the efficacy of the dual encapsulation strategy in significantly improving perovskite material stability, marking a significant step toward their commercial application in optoelectronic lighting.

Accurate measurement of mechanical properties of soft materials by introducing transition layers into test samples

Soft materials loaded by conventional clamps are susceptible to damage caused by local stress concentrations, which leads to inaccurate measurement of strength, toughness, and other important properties. Herein, we propose a facile approach to solve the problem by introducing transition layers to test samples. The effectiveness of the proposed method is demonstrated by experiments and numerical analyses. It is found that the introduction of transition layers can stably and accurately reveal the stress-stretch relationship of soft materials by using the conventional hard clamps. What is more, the transition layers have almost no effect on the fracture toughness measurement for pure soft material samples and those with transition layers. These results should be of great significance for the measurement of various materials, and can serve as a design guidance of various soft material structures in blooming applications.

A high‐order shell finite element for the large deformation analysis of soft material structures

SummaryThis work proposes a higher‐order unified shell finite element for the analysis of cylinders made of compressible and nearly incompressible hyperelastic materials. The nonlinear governing equations are derived employing the Carrera unified formulation (CUF), thanks to which it is possible to build shell elements with the capability to capture three‐dimensional (3D) transverse and out‐of‐plane effects. The material and geometric nonlinearities are expressed in an orthogonal curvilinear reference system and the coupled formulation of hyperelastic constitutive law is considered. The principle of virtual work and a total Lagrangian approach is used to derive the nonlinear governing equations, which are solved by a Newton–Raphson scheme. The numerical investigations deal with a curved arch and both thick and thin cylinders subjected to line and point loadings. The obtained results are validated by comparing them with those from the literature. They demonstrate the reliability of the proposed method to analyze compressible and incompressible hyperelastic shell structures.

Imparting anisotropic performance to soft materials via a magnetically-driven programmable templating-deposition strategy

Creating biomimetic aligned structures in soft materials with fast stimuli-responsive ability and tunable performance is of great interest to intelligent material science. However, there is still a technical challenge to balance the relative velocities of polymeric gelation and nano-alignment/accumulation processes in a controllable manner. Herein, a magnetically-driven programmable templating-deposition strategy coupled with an oscillating electrical signal has been developed to impart tunable anisotropic performance to the soft hydrogels. Specifically, the programmable electrophoretic deposition was initiated from a typical self-aggregated chitosan/Fe3O4 nanoclusters in the presence of an external magnetic field, in which case allows magnetically-driven fast templating of chitosan chains to the electrode surface, oriented/enriched nanoclusters into a compact “fiber-like” aligned structure, and then locked by the electric-field induced localized neutralization processes. An oscillating electrical signal has been used for the first time to manipulate the fiber thickness by varying the ON-OFF electrical signal sequences (e.g., each interruption provides extratimes/chances for nano-assembly), resulting in a higher concentration of magnetic particles and tunable aligned structure to the hydrogels with improved multi-functionalities (e.g., mechanical strength, conductivity, magnetic responsiveness, and photothermal activity). The proof-of-concept for potential applications in the controlled drug delivery system and smart magnetic catheter have also been demonstrated. Consequently, this versatile magnetically-driven programmable templating-deposition approach expands the range of stimuli-responsive materials beyond magnetic hydrogels, inspiring the creation of advanced functional soft materials and devices for wide-broad applications.

Analysis of transversely isotropic compressible and nearly-incompressible soft material structures by high order unified finite elements

This work proposes high-order beam (1D) and plate (2D) finite element models for the large strain analysis of compressible and incompressible transversely isotropic hyperelastic media, defined within the Carrera Unified Formulation (CUF) framework. The strain energy density function adopted in fiber-reinforced hyperelastic materials modeling is presented and expressed in terms of invariants and pseudo-invariants of the right Cauchy-Green strain tensor. The explicit expression of the tangent elasticity tensor is derived through the assumption of coupled formulation of strain energy functions. Refined fully nonlinear beam and plate models are defined in a total Lagrangian formulation, deriving the governing equations of the nonlinear static analysis through the Principle of Virtual Displacements in terms of fundamental nuclei, in resulting expressions of internal and external forces vectors, and tangent stiffness matrix independent of kinematic models and approximation theories adopted. The iterative Newton-Raphson linearization scheme coupled with the arc-length constraint is adopted to obtain actual numerical solutions. Different benchmark analyses in hyperelasticity are performed to assess the capabilities of our proposed model, analyzing the three-dimensional stress field for moderate to large strain states and comparing actual numerical results with exact closed-form solutions or results available in the literature, demonstrating the capabilities and reliability of CUF models in the analysis of fiber-reinforced soft materials and structures.

Elastocapillary rolling transfer weaves soft materials to spatial structures.

Spatial structures of soft materials have attracted great attention because of emerging applications in wearable electronics, biomedical devices, and soft robotics, but there are no facile technologies available to assemble the soft materials into spatial structures. Here, we report a mechanical transfer route enabled by the rotational motion of curved substrates relative to the soft materials on liquid surface. This transfer can weave soft materials into a broad variety of spatial structures with controllable global weaving chirality and orders and could also produce local ear-like folds with programmable numbers and distributions. We further prove that multiple pieces of soft materials in different forms including wire, ribbon, and large-area film can be woven onto curved substrates with various three-dimensional geometry shapes. Application demonstrations on the woven freestanding spatial structures with on-demand weaving patterns and orders have been conducted to show the temperature-driven multimodal actuating functionalities for programmable robotic postures.

Slanted Structure of Blue Phase II Self-Aligned on One-Dimensional Patterned Surfaces.

Orientation analysis of liquid crystal (LC) devices is important for understanding and controlling light propagation behavior in these devices. Blue phases (BPs)─unique LC phases that self-organize into three-dimensional helical structures─are candidate materials for LC-based reflective diffractors. We realized BPII deflectors with large diffraction angles using one-dimensional surface alignment patterns. We analyzed the BPII lattice arrangement in the deflector based on Bragg reflections and demonstrated that the lattice structure was slanted with respect to the substrate, which was confirmed using transmission electron microscopy. In addition, we calculated the similarity between the alignment pattern on the substrate surface and the director arrangement of BPII near the interface, confirming that the structure observed experimentally matched the most probable calculated structure. Thus, this study contributes to the optical design of BPII deflectors and provides information on the orientation mechanism in high-order self-organizing soft matter structures.

Impact of Fat Replacement by Using Organic-Candelilla-Wax-Based Oleogels on the Physicochemical and Sensorial Properties of a Model Cookie.

Oleogelation is an alternative process to improve the nutritional properties of food by creating soft-matter structures with the same functionality as commercial fats (shortenings). In this study, oleogels were produced by adding organic candelilla wax at 3% (OC03), 6% (OC06), and 9% (OC09) to extra-virgin linseed oil, and then characterized by their physicochemical properties. Furthermore, the physicochemical and sensorial properties of five cookie formulations were evaluated. Organic candelilla wax influenced the oleogel formulations, giving higher values of color (L* and b*), texture, acidity index, and melting point. In the cookie formulations, the luminosity values decreased when the percentage of oleogel was increased; reddish trends were obtained (a* values) for the cookie where 70% of the fat was replaced by the oleogel (C70), and more yellow trends were obtained (b* values) for C100. The moisture content was higher in cookies with oleogels, but it was within quality limits. The percentage of fat migration was lower in cookies with a mixture of fats and oleogels. In terms of hardness, the substitution of oleogels resulted in softer cookies. In terms of the sensory evaluation, the most accepted cookie was C70. Therefore, this study demonstrates the possibility of using organic-candelilla-wax-based oleogels in a real food model rich in unsaturated fats.

Water binding and hygroscopicity in π-conjugated polyelectrolytes

The presence of water strongly influences structure, dynamics and properties of ion-containing soft matter. Yet, the hydration of such matter is not well understood. Here, we show through a large study of monovalent π-conjugated polyelectrolytes that their reversible hydration, up to several water molecules per ion pair, occurs chiefly at the interface between the ion clusters and the hydrophobic matrix without disrupting ion packing. This establishes the appropriate model to be surface hydration, not the often-assumed internal hydration of the ion clusters. Through detailed analysis of desorption energies and O–H vibrational frequencies, together with OPLS4 and DFT calculations, we have elucidated key binding motifs of the sorbed water. Type-I water, which desorbs below 50 °C, corresponds to hydrogen-bonded water clusters constituting secondary hydration. Type-II water, which typically desorbs over 50–150 °C, corresponds to water bound to the anion under the influence of a proximal cation, or to a cation‒anion pair, at the cluster surface. This constitutes primary hydration. Type-III water, which irreversibly desorbs beyond 150 °C, corresponds to water kinetically trapped between ions. Its amount varies strongly with processing and heat treatment. As a consequence, hygroscopicity—which is the water sorption capacity per ion pair—depends not only on the ions, but also their cluster morphology.