Bulk transparent supramolecular glass enabled by host-guest molecular recognition.

Supramolecular glass is a non-covalently cross-linked amorphous material that exhibits excellent optical properties and unique intrinsic structural features. Compared with artificial inorganic/organic glass, which has been extensively developed, supramolecular glass is still in the infancy stage, and itself is rarely recognized and studied thus far. Herein, we present the development of the host-guest molecular recognition motifs between methyl-ß-cyclodextrin and para-hydroxybenzoic acid as the building blocks of supramolecular glass. Non-covalent polymerization resulting from the host-guest complexation and hydrogen bonding formation enables high transparency and bulk state to supramolecular glass. Various advantages, including recyclability, compatibility, and thermal processability, are associated with dynamic assembly pattern. Short-range order (host-guest complexation) and long-range disorder (three dimensional polymeric network) structures are identified simultaneously, thus demonstrating the typical structural characteristics of glass. This work provides a supramolecular strategy for constructing transparent materials from organic components.

A supramolecular approach for converting renewable biomass into functional materials.

The rational transformation and utilization of biomass have attracted increasing attention because of its high importance in sustainable development and green economy. In this study, we used a supramolecular approach to convert biomass into functional materials. Six biomass raw materials with distinct chemical structures and physical properties were copolymerized with thioctic acid (TA) to afford poly[TA-biomass]s. The solvent-free copolymerization leads to the convenient and quantitative fabrication of biomass-based versatile materials. The non-covalent bonding and reversible solid-liquid transitions in poly[TA-biomass]s endow them with diversified features, including thermal processability, 3D printing, wet and dry adhesion, recyclability, impact resistance, and antimicrobial activity. Benefiting from their good biocompatibility and nontoxicity, these biomass-based materials are promising candidates for biological applications.

Bulk and transparent supramolecular glass from evaporation-induced noncovalent polymerization of nucleosides.

Understanding the nature of glass is one of the most important challenges in chemistry, physics, and materials science. In this study, transparent bulk supramolecular glasses with excellent optical behaviors and good mechanical properties were fabricated via the non-covalent polymerization of nucleosides. Hydrogen bonding is the main driving force in the formation of bulk supramolecular glasses. The directional and saturated character of hydrogen bonding enables the formation of a short-range ordered structure, while the weak nature and reversibility of hydrogen bonds allow for the asymmetric and random connections of the short-range ordered structure into a long-range disordered network. Various relaxations, including ß, γ, and δ relaxations, are observed at temperatures below the glass transition temperature, demonstrating the metastable nature of bulk supramolecular glasses. This investigation offers supramolecular insights into the nature of glass materials.

Supramolecular Soft Material Enabled by Metal Coordination and Hydrogen Bonding: Stretchability, Self-Healing, Impact Resistance, 3D Printing, and Motion Monitoring.

Metal coordination can significantly improve the macroscopic performance of many materials by enhancing their dynamic features. In this study, two supramolecular interactions, Fe3+ -carboxylic acid coordination, and structural water-induced hydrogen bonding, into an artificial polymer were introduced. Various attractive features, including flexibility and stretchability, are achieved because of the bulk state and dynamic hydrogen bonds of poly(thioctic acid-water) (poly[TA-H]). These unique features are considerably enhanced after the incorporation of Fe3+ cations into poly[TA-H] because metal coordination increased the mobility of the poly[TA-H] chains. Thus, the poly(thioctic acid-water-metal) (poly[TA-HM]) copolymer exhibited better flexibility and stretchability. Moreover, notable underwater/low-temperature self-healing capacity is obtained via the synergistic effect of the metal and hydrogen bonding. Most of the impact energy is quickly absorbed by poly[TA-H] or poly[TA-HM] and effectively and rapidly dissipated via reversible debonding/bonding via the interactions between the metal and hydrogen. Macroscopic plastic deformation or structural failure is not observed during high-speed (50-70 m s-1 ) impact experiments or high-altitude (90 m) falling tests. Furthermore, poly[TA-HM] displayed good thermal molding properties, which enabled its processing via 3D fused deposition modeling printing. Poly[TA-HM] also showed considerable effectiveness for monitoring complicated, dynamic, and irregular biological activities owing to its highly pressure-sensitive nature.

Poly(thioctic acid): From Bottom-Up Self-Assembly to 3D-Fused Deposition Modeling Printing.

Inspired by the bottom-up assembly in nature, an artificial self-assembly pattern is introduced into 3D-fused deposition modeling (FDM) printing to achieve additive manufacturing on the macroscopic scale. Thermally activated polymerization of thioctic acid (TA) enabled the bulk construction of poly(TA), and yielded unique time-dependent self-assembly. Freshly prepared poly(TA) can spontaneously and continuously transfer into higher-molecular-weight species and low-molecular-weight TA monomers. Poly(TA) and the newly formed TA further assembled into self-reinforcing materials via microscopic-phase separation. Bottom-up self-assembly patterns on different scales are fully realized by 3D FDM printing of poly(TA): thermally induced polymerization of TA (microscopic-scale assembly) to poly(TA) and 3D printing (macroscopic-scale assembly) of poly(TA) are simultaneously achieved in the 3D-printing process; after 3D printing, the poly(TA) modes show mechanically enhanced features over time, arising from the microscopic self-assembly of poly(TA) and TA. This study clearly demonstrates that micro- and macroscopic bottom-up self-assembly can be applied in 3D additive manufacturing.

Deep eutectic solvents-based three-phase partitioning for tomato peroxidase purification: A promising method for substituting t-butanol.

T-butanol is widely used in three-phase partitioning (TPP). This study used deep eutectic solvents (DESs) to substitute t-butanol for tomato peroxidase (POD) purification. DES-5 (menthol and octanoic acid) was screened as the optimal solvent. The extraction process was optimized using single-factor experiments. Thereafter, the major three factors were optimized by response surface methodology (RSM). When the ammonium sulfate ((NH4)2SO4) concentration was 42%, DES: crude extract (v/v) was 2:1, pH was 5.7, and extraction temperature was 30 °C, the recovery and purification fold reached a maximum of 104.71% and 9.76, respectively. The obtained tomato POD was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), which showed that this system could effectively purify POD. Finally, recycling studies indicated the good cycle stability of the DES. This TPP based on DESs is greener and more efficient, indicating that DESs can be good alternative solvents for further applications of TPP.

Underwater luminescent labeling materials constructed from a supramolecular approach.

Underwater labeling under complicated conditions is challenging for modern adhesive materials. In this work, a series of supramolecular polymer adhesives were successfully prepared via the non-covalent copolymerization of low-molecular-weight monomers (thioctic acid (TA) and tetraphenylethene derivatives (TPEs)). Strong adhesion effects were observed under various conditions. The poly(TA-TPE)s showed long-term stability in underwater labeling. Due to the aggregation-induced emission (AIE) behavior of TPEs, poly(TA-TPE)s showed great potential as fluorescent labeling materials in water. Complicated and cryptographic information can be stored in labeling structures, and analyzed under ultraviolet (UV) irradiation. Supramolecular labeling showed excellent distinguishability in complex backgrounds. Meanwhile, fluorescent adhesives exhibited a number of advantages over visible colored labels.

On-Site Supramolecular Adhesion to Wet and Soft Surfaces via Solvent Exchange.

A series of poly(thioctic acid-catechol)s was prepared by supramolecular copolymerization of two low-molecular-weight monomers, thioctic acid (TA) and catechol (CA). The addition of a small amount of CA molecules significantly improved the adhesion ability of poly(TA) and transformed it into an applicable supramolecular polymer adhesive material. The robust adhesion of poly(TA-CA)s to soft surfaces was achieved by employing a hot-melt method. However, the supramolecular adhesion via the hot-melt method failed to perform in the presence of water. On-site supramolecular adhesion to wet and soft substrates was successfully realized through the solvent exchange behavior between water and the poly(TA-CA)s ethanol solution. Compared to the hot-melt method, the solvent exchange method displays various fascinating advantages and is suitable for adhesion conditions normally under the presence of water.

Two birds with one stone: Porous poly(ionic liquids) membrane with high efficiency for the separation of amino acids mixture and its antibacterial properties.

Poly(ionic liquid) membranes (PILMs) can be potentially applied as polyelectrolyte materials in the separation of ampholytes such as amino acids. Therefore, poly(amino acid ionic liquid) membranes (PAAILMs) were prepared by blending poly(amino acid ionic liquids) (PAAILs) and polyvinylidene fluoride (PVDF) in this study. These PAAILMs were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA). Moreover, their mechanical properties, antibacterial and antifouling properties were evaluated. The zeta potential, pore size distribution, porosity, and specific surface area of these membranes were also measured. The membranes were used to separate the amino acid mixture of l-phenylalanine and l-aspartic acid, which are essential for the synthesis of aspartame. The PAAILMs can be used for the selective separation of l-phenylalanine and l-aspartic acid through the Donnan effect. A maximum selectivity of 65% was obtained for the mixed amino acids via one-step separation. These PAAILMs have the advantages of low operating pressure, high water flux, good antibacterial and antifouling properties, and excellent reusability, thereby indicating their potential for industrial application in the separation of l-phenylalanine and l-aspartic acid.

Deep Eutectic Supramolecular Polymers: Bulk Supramolecular Materials.

Application of new strategies for supramolecular self-assembly can significantly impact the properties and/or functions of supramolecular polymers. To realize a facial strategy for the development of solvent-free supramolecular polymers in bulk, "deep eutectic solvents" were employed. Cyclodextrins and natural acids were used to prepare deep eutectic supramolecular polymers (DESPs). Deep eutectic solvents have special characteristics that endow DESPs with unique macroscopic properties and excellent processability. DESPs exhibit supramolecular adhesion and temperature-dependent behavior originating from the combined effects of deep eutectic solvents and supramolecular polymerization. Because DESPs are solvent-free and display interesting macroscopic properties, they have potential as new adaptive materials.

Extraction and preliminary purification of polysaccharides from Camellia oleifera Abel. seed cake using a thermoseparating aqueous two-phase system based on EOPO copolymer and deep eutectic solvents.

A thermoseparating aqueous two-phase system (ATPS) based on ethylene oxide-propylene oxide (EOPO) copolymer and deep eutectic solvents (DES) was developed for the extraction and preliminary purification of polysaccharides in Camellia oleifera Abel. seed cake. DESs were used as the extraction media for obtaining the crude extract. The maximum extraction yield (Y) of polysaccharides was 152.37 mg/g in the crude extract. Then the crude polysaccharides were extracted and preliminary purified by EOPO/DES ATPS. The maximum extraction efficiency (E.E.) of polysaccharides was 86.91% in EOPO-rich phase by the first ATPS extraction. The EOPO-rich phase was separated and the polysaccharides were recovered by temperature-induced phase separation. The maximum recovery efficiency (R.E.) was 84.92% in aqueous phase by the second ATPS extraction. This thermoseparating ATPS possesses the merits of good environment-friendlies, simple operation, and easy recovery of components, which can be used as an efficient method for the extraction and separation of polysaccharides.