Supermolecular Structure Research Articles

Nanocellulose‐polypropylene composites with novel antimicrobial complex salt

AbstractPolypropylene composites with different contents of zinc‐ammonium salts (3, 5 and 7 wt%) and nanocellulose (1 wt%) after enzymatic bioconversion were characterized by structural, dispersion‐morphological, thermal, antimicrobial and mechanical analysis. It was shown that the use of a newly synthesized salt significantly affected the formation of the supermolecular structure of the polymer matrix and increased the nucleation activity, thermostability and flexibility of the composite materials. Moreover, the addition of the inorganic filler allowed to obtain composites with very good antimicrobial properties against Staphylococcus aureus, Escherichia coli and Candida albicans. An interesting relationship between the degree of filler dispersion in the polymer matrix and the formation of polymorphic varieties was elucidated in the study, which contributes to the improvement of final performance characteristics of composite materials. It is noteworthy that a hybrid filler in the form of nanometric cellulose and a biocidal additive containing zinc‐ammonium complex salt was used for the first time. Research has shown that such polymer composites can find application during the manufacture of smart packaging materials with enhanced barrier properties against oxygen and water vapor as well as improved biocidal characteristics, which will notably extend food storage time. At the same time, the presented process of obtaining the innovative composite materials is an excellent example of sustainable technologies for the design of antimicrobial treatments, while guaranteeing the possibility of further processing of these composite materials through material recycling.Highlights Zinc‐ammonium complex with antimicrobial properties was obtained The strength properties and thermal stability of the composites were improved Degree of filler dispersion in polymer affects formation of polymorphic varieties The composites can be applied in the production of smart packaging materials

Stereoisomeric separation and chiral recognition mechanism study of star cyclodextrin polymer as the chiral stationary phase

BackgroundAs the derivatives of cyclodextrin (CD), cyclodextrin polymers (CDPs) effectively increase the concentration of CD units and construct supramolecular structures with unique stereoselectivity by the structure design. CDPs have shown significant potential in chiral separation, however, the process of stereoselective interactions on chiral stationary phases (CSPs) and the specific contribution of intermolecular forces are still a challenge issue. A comprehensive understanding of the chiral recognition mechanism of CDPs will help to optimize chiral separation conditions and design new CSPs. ResultsThe star CDP with a supermolecular structure was synthesized by grafting β-CD onto the external 6-position hydroxyl groups using β-CD as the parent nucleus. The enhanced host-guest recognition ability of CD supramolecular polymer structure provided better inclusion interaction and increased chiral recognition of the isomers. The Star-CD CSP with star CDP as a chiral ligand performed satisfactory stereoisomer separation ability with the separation factor (α) up to 2.0 for various quinoline alkaloid isomers and 1.89 for catechins. To elucidate its chiral separation mechanism, molecular docking was used to construct the three-dimensional visual models of the binding sites and the contribution of non-covalent interactions between Star-CD CSP and quinoline alkaloid isomers. In addition, the formation sites of non-covalent interactions on the CD monomers of the polymer side chains were confirmed from the actual geometric structure by analyzing the NMR chemical shift changes before and after the formation of complexes between Star-CD polymers and isomers. Combined with the mutual evidence of molecular simulation and chiral NMR, the specific recognition mechanism of selector-selectand complexes was comprehensively expounded. SignificanceThe multi-mode CSP based on cyclodextrin supramolecular structure provides new ideas for the stereoisomeric separation of complex chiral components with multiple chiral centers in natural products. Not limited to the macroscopic performance of the chromatographic separation, molecular docking explored the theoretical model of chiral recognition from the molecular level. The chiral NMR analysis confirmed the credibility of the model from the geometry structure, and then the recognition mechanism of multi-mode CSP was fully elaborated combining the above three aspects.

The Coloristic Properties of Biodegradable Fibers

This work aims to present the results of evaluating the coloristic properties of polylactic acid (PLA) fibers. PLA is common nowadays in much research, as it is a biodegradable plastic from renewable sources. However, little research is devoted to PLA fibers, and even less to applied research of colored fibers. The prepared color masterbatches, created using inorganic pigments, such as titanium dioxide and carbon black, were subsequently used to prepare dyed PLA fibers in mass. The fibers were drawn to the maximum drawn ratio. The properties of the pure and dyed fibers were investigated before and after accelerated light aging using Q-SUN equipment. The changes were recorded by Fourier Transform Infrared (FTIR) spectroscopy and colorimetric properties were recorded using a device spectrometer from TECHKON SpectroDens. We also evaluated thermal properties from the first heating via differential scanning calorimetry (DSC). The measurements were taken before and after the aging of the PLA fibers, in order to see the effect of aging on the supermolecular structure, excluding the influence of the preparation process and the influence of the kind of PLA. Using inorganic pigments showed sufficient color stability even after accelerated light aging, which is beneficial for using colored fibers in practice.

Group superatoms: A new concept in cluster science

A promising research area in nanomaterials is the use of superatomic clusters as building blocks for creating novel molecules or materials with tailored properties. However, assembling these superatoms into functional materials is challenging, and a thorough understanding of this process is still lacking. In this study, we introduce a new concept called the “superatomic family,” which refers to superatoms that share similar valence electron structures but differ in size. We demonstrate this concept with the synthesized [Au6{Ni3(CO)6}4]2− cluster and the designed [Au16{Ni6(CO)10}4]2− and [Au31{Ni10(CO)15}4]5− clusters. These serve as analogs to simple hydrocarbons, such as methane (CH4), silicon hydride (SiH4), and germanium hydride (GeH4). In these supermolecular structures, the central cores of Au6, Au16, and Au31 exhibit the formation of superatomic SP3 hybridized orbitals, which influence the molecular shape and bonding. Moreover, we explored superatomic bonding involving SP3–SP3 hybridized cores, representing a single superatomic bond between members of the superatomic family, analogous to CH3–SiH3 bonds. By integrating the concept of group superatoms into the Lewis structure framework, we present a powerful approach for predicting and engineering cluster properties, thus opening a vast landscape of nanomaterial design possibilities.

Luminescence properties of endohedrally doped group-IV clusters.

Endohedrally doped clusters form a large category of cage clusters, with unique structures, diverse elemental compositions, and highly tunable electronic structures and physisochemical properties. They have been widely achieved in laboratory and may serve as functional building blocks for assembling new supermolecular structures and devices. In this paper, for the first time, we disclosed the luminescence properties of endohedrally doped group-IV clusters by time-dependent density functional theory calculations. A total of 64 cage clusters have been explored in terms of stability, emission wavelength, and the energy difference between the first excited singlet and triplet states. The key geometric and electronic factors governing the photophysical properties of these cage clusters were unveiled, to provide crucial insights for crafting atomically precise nanoclusters for optical and optoelectronic applications.

Wireless Sensor System Based on Organohydrogel Ionic Skin for Physiological Activity Monitoring.

Supermolecular hydrogel ionic skin (i-skin) linked with smartphones has attracted widespread attention in physiological activity detection due to its good stability in complex scenarios. However, the low ionic conductivity, inferior mechanical properties, poor contact adhesion, and insufficient freeze resistance of most used hydrogels limit their practical application in flexible electronics. Herein, a novel multifunctional poly(vinyl alcohol)-based conductive organohydrogel (PCEL5.0%) with a supermolecular structure was constructed by innovatively employing sodium carboxymethyl cellulose (CMC-Na) as reinforcement material, ethylene glycol as antifreeze, and lithium chloride as a water retaining agent. Thanks to the synergistic effect of these components, the PCEL5.0% organohydrogel shows excellent performance in terms of ionic conductivity (1.61 S m-1), mechanical properties (tensile strength of 70.38 kPa and elongation at break of 537.84%), interfacial adhesion (1.06 kPa to pig skin), frost resistance (-50.4 °C), water retention (67.1% at 22% relative humidity), and remoldability. The resultant PCEL5.0%-based i-skin delivers satisfactory sensitivity (GF = 1.38) with fast response (348 ms) and high precision under different deformations and low temperature (-25 °C). Significantly, the wireless sensor system based on the PCEL5.0% organohydrogel i-skin can transmit signals from physiological activities and sign language to a smartphone by Bluetooth technology and dynamically displays the status of these movements. The organohydrogel i-skin shows great potential in diverse fields of physiological activity detection, human-computer interaction, and rehabilitation medicine.

Structure and Properties of Polylactide Composites with TiO2-Lignin Hybrid Fillers.

The research presented in this article focuses on the use of inorganic-organic material, based on titanium dioxide and lignin, as a filler for polylactide (PLA) biocomposites. To date, no research has been conducted to understand the impact of hybrid fillers consisting of TiO2 and lignin on the supermolecular structure and crystallization abilities of polylactide. Polymer composites containing 1, 3 or 5 wt.% of hybrid filler or TiO2 were assessed in terms of their structure, morphology, and thermal properties. Mechanical properties, including tensile testing, bending, impact strength, and hardness, were discussed. The hybrid filler is characterized by a very good electrokinetic stability at pH greater than 3-4. The addition of all fillers led to a small decrease in the glass transition temperature but, most importantly, the addition of 1% of the hybrid filler to the PLA matrix increased the degree of crystallinity of the material by up to 20%. Microscopic studies revealed differences in the crystallization behavior and nucleation ability of fillers. The use of hybrid filler resulted in higher nucleation density and shorter induction time than in unfilled PLA or PLA with only TiO2. The introduction of small amounts of hybrid filler also affected the mechanical properties of the composites, causing an increase in bending strength and hardness. This information may be useful from a technological process standpoint and may also help to increase the range of applicability of biobased materials.

Enhancing Sustainability and Antifungal Properties of Biodegradable Composites: Caffeine-Treated Wood as a Filler for Polylactide.

This study investigates the suitability of using caffeine-treated and untreated black cherry (Prunus serotina Ehrh.) wood as a polylactide filler. Composites containing 10%, 20%, and 30% filler were investigated in terms of increasing the nucleating ability of polylactide, as well as enhancing its resistance to microorganisms. Differential scanning calorimetry studies showed that the addition of caffeine-treated wood significantly altered the crystallization behavior of the polymer matrix, increasing its crystallization temperature and degree of crystallinity. Polarized light microscopic observations revealed that only the caffeine-treated wood induced the formation of transcrystalline structures in the polylactide. Incorporation of the modified filler into the matrix was also responsible for changes in the thermal stability and decreased hydrophilicity of the material. Most importantly, the use of black cherry wood treated with caffeine imparted antifungal properties to the polylactide-based composite, effectively reducing growth of Fusarium oxysporum, Fusarium culmorum, Alternaria alternata, and Trichoderma viride. For the first time, it was reported that treatment of wood with a caffeine compound of natural origin alters the supermolecular structure, nucleating abilities, and imparts antifungal properties of polylactide/wood composites, providing promising insights into the structure-properties relationship of such composites.

Hyaluronan oligosaccharides form double-helical duplexes in water:1,4-dioxane mixed solvent

Hyaluronic acid (HA) is a hydrophilic natural polysaccharide consisting of alternating monosaccharide units of glucuronic acid and N-acetyl glucosamine. In aqueous solutions the electrostatic repulsion of the carboxylate groups hampers the formation of supermolecular structures that can be partially stabilized by the addition of salt. Increased permittivity of the mixed water:organic solvents causes better compensation of the negative charge of HA chains by dissolved cations which changes their interactions with other molecules. In this study we simulate interactions of two HA chains in water:1,4-dioxane and water:tert-butanol mixed solvents with varying NaCl concentrations using molecular dynamics (MD). Anti-parallel double-helix-like duplexes are formed in NaCl-containing water:1,4-dioxane mixture and remain stable even when NaCl is removed. Parallel duplexes separate after a short time. In water:tert-butanol analogous duplexes are unstable. Stability of HA duplexes is thus determined by the solvent composition and the ability of its components to separate in the solvation shell of HA molecules, as well as by the mutual orientation of the chains.

Polypropylene Composites with Biochars from Miscanthus and Tomato Biomass – Part I: Thermal and Structural Properties

ABSTRACT A study of biochar/polypropylene composites has been conducted to describe the influence of biochars on the supermolecular structure of PP. The first stage of the work described the influence of carbonization on the properties of carbon fillers (tomato and miscanthus). The biochar was added to the polymer matrix, and the composite samples were manufactured by extrusion and injection molding. The influence of the fillers was investigated using WAXS, hot-stage optical microscopy, PLM microscopy, FTIR and ASTM designation. There were showed the strong influence of the biochar fillers on the properties of polypropylene matrix in composite materials. Obtained composites were characterized by the satisfying properties.

X-ray study on crystalline morphology in iPP/MMT nanocomposite fibers

Nanocomposite fibers based on isotactic polypropylene (iPP) and an organically modified montmorillonite (MMT), Cloisite 15A, were formed from the melt at different take-up velocity. The studies were performed for pure iPP fibers and fibers containing three different concentrations of MMT. The supermolecular structures of the fibers at the crystallographic and lamellar levels were examined by means of X-ray scattering methods (WAXS and SAXS). It was found that the dominant crystal form of iPP is α modification. The increase of take-up velocity induces the orientation of iPP crystals parallel to the fiber axis. The cross-hatching crystallization of iPP was also observed in the tested fibers. Only for the gravity spun fibers containing MMT, the β modification of iPP was observed. Assuming that nucleation does not occur on the surfaces of clay platelets but rather in the interlayers of MMT particles, a probable β-phase nucleation mechanism has been suggested. This mechanism was confirmed by the isothermal crystallization experiment. During heating, the β crystalline form transformed into α-form. The degree of transformation depended on the annealing temperature. The studies also revealed that lamellar stacks of iPP are perpendicular to the MMT layers surfaces.

Advanced nanocellulose hybrid fillers for sustainable polypropylene biomaterials with enhanced oxygen barrier properties

Research was undertaken on the design and preparation of advanced polymer biomaterials containing innovative nanocellulose hybrid fillers with functional physicochemical properties, characterized by high mechanical strength, enhanced thermal resistance, and improved gas barrier properties, which are important in the packaging industry. Such innovative polymer composite nanomaterials with renewable fillers, which will reduce the consumption of petroleum raw materials, which is also directly related to the reduction of energy consumption. Novel TiO2-ZnO/nanocellulose hybrid systems were prepared by a solvothermal method, and their structural, textural, morphological, chemical composition, and thermal properties were evaluated. Polymer composites with nanocellulose synthesized using enzymatic hydrolysis and with hybrid fillers, were obtained by two-step extrusion. Various techniques were used to determine the supermolecular structure and nucleation activity of the biomaterials, barrier tests and mechanical properties were also carried out. It was found that the composites containing hybrid fillers exhibited increased nucleation activity, which favored the formation of a pseudohexagonal polymorphic variety of the polymer matrix, providing high tensile strength while maintaining high flexibility. In addition, the use of novel hybrid fillers made it possible to achieve higher barrier properties against oxygen and water vapor in composite films. A significant achievement is the finding of a previously unrecorded relationship between the shaping of supermolecular structure (polymorphism, nucleation) and physicochemical properties (mechanical, barrier), which is of great significance for the design of modern packaging.

Intermolecular interactions enabled a semiconducting 2D supermolecular complex with robust humidity sensing performance

As essential multifunctional materials, metal-organic complexes are attractive candidates showing superior sensing performance. However, the development of complex-based electronic sensors is still greatly limited by the low conductivity and unsatisfactory properties. Here, we report a new complex with formula of [Cd2(TAA)4(2,2′-bpy)2] (denoted as CdL, HTAA = 3-thiopheneacetic acid, 2,2′-bpy = 2,2′-bipyridine) synthesized via room-temperature precipitation. Hirshfeld surface analysis reveals the important effects of hydrogen bonds (54.6%) and Van der Waals interaction (31.5%) for constructing its 2D supermolecular structure. Favored by these intermolecular interactions, the semiconducting CdL exhibits high electronic conductivity at room temperature (1.71 × 10−5 S/cm). Consequently, the CdL powder was fabricated into a planar impedimetric device with high performance. Particularly, the CdL sensor exhibited high sensitivity (1.2 × 103), fast response (6 s), and small hysteresis (0.92%) in total relative humidity range of 33%−97%. In addition, complex impedance analysis was adopted to clarify the sensing mechanism of CdL. This contribution demonstrates the possible application of low-dimensional complexes in humidity sensors.

Caffeine-treated wood as an innovative filler for advanced polymer composites

Polymer composites, based on the wood flour originating from an invasive black cherry (Prunus serotina Ehrh.) treated with caffeine to achieve increased bio-resistance, were obtained in this study. The caffeine-treated wood had a significant effect on the supermolecular structure of polymer matrix, resulting in a high content of polymorphic β-PP phase, as well as an increase in nucleation activity of wood surface. The caffeine treatment of wood was an effective method of achieving increased resistance of composites to selected fungi and bacteria while maintaining good mechanical strength and thermal resistance. Addition of black cherry wood to polymer matrix induced inhibition of the release of volatile organic compounds. Increased resistance to fungi and bacteria depended on formation a significant amount of the β-phase up to 35% in the composite with 30% of caffeine-treated wooden filler and a simultaneous decrease in crystallinity from 52% for pure PP to 45% for mentioned composite.

New Insights on the Biomechanics of the Fetal Membrane.

During pregnancy, the Fetal Membrane (FM) is subjected to mechanical stretching that may result in preterm labor. The structural integrity of the FM is maintained by its collagenous layer. Disconnection and reconnection of molecular bonds between collagen fibrils is the fundamental process that governs the irreversible mechanical and supramolecular changes in the FM. At a critical threshold strain, bundling and alignment of collagen fibrils alter the super-molecular structure of the collagenous layer. Recent studies indicate that these changes are associated with inflammation and/or expression of specific proteins that are known to be related to uterine contractions and labor. The potential healing of stretching-induced damages in the FM by mediators involved in mechano-transduction is discussed.

Encapsulation of catechin derivatives in single-walled carbon nanotubes

This study explores the encapsulation dynamics and interaction mechanisms of catechin derivatives within single-walled carbon nanotubes (SWNTs) using molecular dynamics simulations. We assessed the strength of π-π stacking interactions between catechin derivatives and SWNTs by analyzing the distance evolution between aromatic rings, mean square displacement (MSD), and diffusion coefficient (D) values. The results revealed that interaction strength varied depending on the specific derivative and concentration. At low and medium concentrations, weaker interactions were observed for catechin, epicatechin, and epigallocatechin, while stronger interactions were found for epicatechin gallate and epigallocatechin gallate. Furthermore, MSD values indicated normal diffusion trends for catechin, epicatechin, and epigallocatechin, suggesting free movement within SWNTs. In contrast, sub-diffusion trends were observed for epicatechin gallate and epigallocatechin gallate, indicating limited mobility. This study offers insights into the interactions of catechin derivatives with SWNTs, enriching our understanding of supermolecular structure development and enabling potential applications in drug delivery, and biosensors.

Efficient Synthesis of Imine-Carboxylic Acid Functionalized Compounds: Single Crystal, Hirshfeld Surface and Quantum Chemical Exploration.

Two aminobenzoic acid based crystalline imines (HMBA and DHBA) were synthesized through a condensation reaction of 4-aminobenzoic acid and substituted benzaldehydes. Single-crystal X-ray diffraction was employed for the determination of structures of prepared Schiff bases. The stability of super molecular structures of both molecules was achieved by intramolecular H-bonding accompanied by strong, as well as comparatively weak, intermolecular attractive forces. The comparative analysis of the non-covalent forces in HMBA and DHBA was performed by Hirshfeld surface analysis and an interaction energy study between the molecular pairs. Along with the synthesis, quantum chemical calculations were also accomplished at M06/6-311G (d, p) functional of density functional theory (DFT). The frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP), natural bond orbitals (NBOs), global reactivity parameters (GRPs) and natural population (NPA) analyses were also carried out. The findings of FMOs found that Egap for HMBA was examined to be smaller (3.477 eV) than that of DHBA (3.7933 eV), which indicated a greater charge transference rate in HMBA. Further, the NBO analysis showed the efficient intramolecular charge transfer (ICT), as studied by Hirshfeld surface analysis.

Molecular dynamics of He encapsulation in the C20H20 cage at the threshold energy

The encapsulation of He inside C20H20 cage has been investigated in the framework of molecular dynamics for incident atom energy in a range close to the threshold value, corresponding to the projectile passing through the pentagonal carbon ring. The entrance of He atom into dodecahedrane is analyzed in terms of static and dynamic potential barriers. The details of helium capture inside the molecular box is revealed by using geometric and energetic parameters, being associated with the response of the atomic configuration near the collision site on the C20H20 cage. The energy transferred from the incident atom to deformation, vibrations, and recoil of the molecule target, was calculated as a function of the distance between the projectile and the collision site on C20H20 cage. The calculations show that the noble gas atom, encapsulated at the threshold of 315.62 Å/ps, oscillates across the void of the dodecahedrane with frequencies of 2.5, 22.5, and 25.0 THz, monitored for a time interval of 10 ps starting at helium penetration into C20H20. Molecular dynamics calculations are based on ab-initio Hartree-Fock method, considering an adiabatic process. This study reveals advantageous features of helium encapsulation in dodecahedrane molecules in designing super-molecular structures for advanced nano sensors in the field of THz detectors.

Nanocellulose-Based Polymer Composites Functionalized with New Gemini Ionic Liquids.

The manuscript discusses the application of dimeric imidazolium ionic liquids with an aliphatic linker of different lengths, constituting a new class of compounds called gemini, for the modification of renewable materials. This innovative functionalization with the use of ionic liquids made it possible to obtain polymer composite nanomaterials with renewable fillers, which will reduce the consumption of petroleum-based raw materials and also be directly related to the reduction of energy intensity. Renewable filler in the form of nanocellulose modified with ionic liquids, as well as polymer composites with such filler obtained by extrusion and injection molding techniques, were subjected to detailed characterization using techniques like: X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), dispersion studies (DLS), morphological analysis (SEM), differential scanning calorimetry (DSC), hot-stage polarized light microscopy and characterization of mechanical properties. The use of innovative dimeric ionic liquids proved to be an effective method to carry out efficient functionalization of cellulose. This provided a stable space structure between polysaccharide particles, limiting aggregate formation. It was shown that chemical modification with ionic liquids has a significant effect on the nucleation activity of cellulose fillers and the formation of the supermolecular structure of the polymer matrix, which consequently allowed to obtain polymer composites with excellent strength characteristics and increased flexibility, which will allow to increase their application potential. Innovative ionic liquids have contributed to obtaining green nanomaterials with excellent functional properties, which have not been described in the literature so far.

High Amylose Corn Starch Gels—Investigation of the Supermolecular Structure

AbstractAqueous gels based on two high amylose corn starch (HACS) genotypes with different amylose (AM) contents (HYLON V [HACS‐50] and HYLON VII [HACS‐70]) are prepared by gradation of the polymer concentration (6 and 9% w/w) and storage duration (1 and 14 days). The supermolecular structure of the wet gels is investigated by means of confocal laser scanning microscopy (CLSM), and the dried starch gel material examines crystallographically using X‐ray diffraction (XRD) and morphologically using scanning electron microscopy (SEM). In particular CLSM reveals that the gel structure shows changes with the storage time. XRD experiments reveal the existence of the B‐type crystalline structure as well as a remarkable portion of the V‐type, and higher crystallinity (Xc) is found after long‐term storage. Observation of the dried gel material's surface facilitates the assumption of a fractal‐based arrangement (structure of retrograded starch) within the starch gel network. The results are discussed closely with obtained data related to the molecular level of the gel matrix involved starch polymers, which are reported in previous publications.