Glass-Blowing-Inspired Upcycling of Thermosetting Polymer to Neuron-Like Hierarchical Carbon for Microwave Absorption and Conversion.

Upgrading thermosetting polymer waste and harvesting unwanted electromagnetic energy are of great significance in solving environmental pollution and energy shortage problems. Herein, inspired by the glass-blowing art, a spontaneous, controllable, and scalable strategy is proposed to prepare hollow carbon materials by inner blowing and outside blocking. Specifically, hierarchically neuron-like hollow carbon materials (HCMSs) with various sizes are fabricated from melamine-formaldehyde sponge (MS) waste. Benefiting from the synergistic of the hollow "cell body" and the connected "protrusions" networks, HCMSs reveal superior electromagnetic absorption performance with a strong reflection loss of -54.9 dB, electromagnetic-heat conversion ability with a high conversion efficiency of 34.4%, and efficient energy storage performance in supercapacitor. Furthermore, a multifunctional device integrating electromagnetic-heat-electrical energy conversion is designed, and its feasibility is proved by experiments and theoretical calculations. The integrated device reveals an output voltage of 34.5 mV and a maximum output power of 0.89 µW with electromagnetic radiation for 60 s. This work provides a novel solution to recycle polymer waste, electromagnetic energy, and unwanted thermal energy.

Ultrahigh Heat/Fire-Resistant, Mechanically Robust, and Closed-Loop Chemical Recyclable Polycarbonate Enabled by Facile Bond Dissociation Energy Modulation.

Plastics serve as an essential foundation in contemporary society. Nevertheless, meeting the rigorous performance demands in advanced applications and addressing their end-of-life disposal are two critical challenges that persist. Here, an innovative and facile method is introduced for the design and scalable production of polycarbonate, a key engineering plastic, simultaneously achieving high performance and closed-loop chemical recyclability. The bisphenol framework of polycarbonate is strategically adjusted from the low-bond-dissociation-energy bisphenol A to high-bond-dissociation-energy 4,4'-dihydroxydiphenyl, in combination with the incorporation of polysiloxane segments. As expected, the enhanced bond dissociation energy endows the polycarbonate with an extremely high glow-wire flammability index surpassing 1025 °C, a 0.8 mm UL-94 V-0 rating, a high LOI value of 39.2%, and more than 50% reduction of heat and smoke release. Furthermore, the π-π stacking interactions within biphenyl structures resulted in a significant enhancement of mechanical strength by as more as 37.7%, and also played a positive role in achieving a lower dielectric constant. Significantly, the copolymer exhibited outstanding closed-loop chemical recyclability, allowing for facile depolymerization into bisphenol monomers and the repolymerized copolymer retains its high heat and fire resistance. This work provides a novel insight in the design of high-performance and closed-loop chemical recyclable polymeric materials.

Nano-Interfacial Supramolecular Adhesion of Metal-Organic Framework-Based Separator Enables High-Safety and Wide-Temperature-Range Lithium Batteries.

Polyolefin separators are the most commonly used separators for lithium batteries; however, they tend to shrink when heated, and their Li+ transference number (t Li +) is low. Metal-organic frameworks (MOFs) are expected to solve the above problems due to their high thermal stability, abundant pore structure, and open metal sites. However, it is difficult to prepare high-porosity MOF-based membranes by conventional membrane preparation methods. In this study, a high-porosity free-standing MOF-based safety separator, denoted the BCM separator, is prepared through a nano-interfacial supramolecular adhesion strategy. The BCM separator has a large specific surface area (450.22 m2 g-1) and porosity (62.0%), a high electrolyte uptake (475 wt%), and can maintain its morphology at 200 °C. The ionic conductivity and t Li + of the BCM separator are 1.97 and 0.72 mS cm-1, respectively. Li//LiFePO4 cells with BCM separators have a capacity retention rate of 95.07% after 1100 cycles at 5  C, a stable high-temperature cycling performance of 300 cycles at 80 °C, and good capacity retention at -40 °C. Li//NCM811 cells with BCM separators exhibit significantly improved rate performance and cycling performance. Pouch cells with BCM separators can work at 120 °C and have good safety at high temperature.

Engineering Biodegradable Polyurethanes with Precisely Controlled Hierarchical Structures to Access Shape Memory Effect and Enhanced Bioactivities.

Biodegradable polymers with shape memory effects (SMEs) offer promising solutions for short-term medical interventions, facilitating minimally invasive procedures and subsequent degradation without requiring secondary surgeries. However, achieving a good balance among desirable SMEs, mechanical performance, degradation rate, and bioactivities remains a significant challenge. To address this issue, we established a strategy to develop a versatile biodegradable polyurethane (PPDO-PLC) with tunable hierarchical structures via precise chain segment control. Initial copolymerization of l-lactide and ε-caprolactone sets a tunable Tg close to body temperature, followed by block copolymerization with poly(p-dioxanone) to form a hard domain. This yields a uniform microphase-separation morphology, ensuring robust SME and facilitating the development of roughly porous surface structures in alkaline environments. Cell experiments indicate that these rough surfaces significantly enhance cellular activities, such as adhesion, proliferation, and osteogenic differentiation. Our approach provides a methodology for balancing biodegradability, SMEs, three-dimensional (3D) printability, and bioactivity in materials through hierarchical structure regulation.

A Rule for Response Sensitivity of Structural-Color Photonic Colloids.

To mimic natural photonic crystals having color regulation capacities dynamically responsive to the surrounding environment, periodic assembly structures have been widely constructed with response materials. Beyond monocomponent materials with stimulus responses, binary and multiphase systems generally offer extended color space and complex functionality. Constructing a rule for predicting response sensitivity can provide great benefits for the tailored design of intelligently responsive photonic materials. Here, we elucidate mathematical relationships between the response sensitivity of dynamically structural-color changes and the location distances of photonic co-phases in three-dimensional Hansen space that can empirically express the strength of their interaction forces, including dispersion force, polarity force, and hydrogen bonding. Such an empirical rule is proven to be applicable for some typical alcohols, acetone, and acetic acid regardless of their molecular structures, as verified by angle resolution spectroscopy, in situ infrared spectroscopy, and molecular simulation. The theoretical method we demonstrate provides rational access to custom-designed responsive structural coloration.

An Integrative Chemical Recycling Approach for Catalytic Oxidation of Epoxy Resin and in situ Separation of Degraded Products.

Although many approaches have been proposed to recycling waste epoxy resin (EP), the separation of mixed degraded products remains a challenge due to their similar structures. To address this, we present a catalytic oxidation strategy that enables mild degradation of EP and in situ separation of degraded products through supramolecular interactions. The oxidative degradation relies on FeIV=O radicals with strong oxidizing properties, which are generated from the electron transfer of FeCl2 with reaction reagents. As the FeIV=O radicals attacked the C-N bonds of EP, EP was broken into fragments rich in active functional groups. Meanwhile, the FeIV=O radicals were reduced to iron ions that can coordinate with the carboxyl groups on the fragments. As a result, the degraded products with different carboxyl content can be effortlessly separated into liquid and solid phase by coordinating with the catalyst. The success of this work lays the foundation for high-value application of degraded products and provides new design ideas for recycling waste plastics with complex compositions.

Dynamic Shape Change of Liquid Crystal Polymer Based on An Order-Order Phase Transition.

Liquid crystal actuators conventionally undergo shape changes across an order-disorder phase transition between liquid crystal (LC) and isotropic phases. In this study, we introduce an innovative Liquid Crystal Polymer (LCP) actuator harnessing an order-order LC phase transition mechanism. The LCP film is easily stretchable within the LC phase, facilitated by the π-π stacking of phenyl groups serving as robust physical crosslinking points, and thereby transforms to a stable monodomain structure. The resultant monodomain LCP actuator shows a distinctive reversible dynamic shape change, exhibiting extension followed by contraction along the LC director on cooling. The extension is propelled by the reversible smectic C to smectic A phase transition, and the contraction is attributed to the re-entry to the smectic C phase from smectic A phase. Thermal annealing temperature determines this peculiar dynamic shape change, which occurs during both heating and cooling processes. This pivotal attribute finds manifestation in gripper and flower-shaped actuators, adeptly executing grabbing and releasing as well as blooming and closure motions within a single thermal stimulation. In essence, our study introduces an innovative approach to the realm of LCP actuators, ushering in a new avenue for the design and fabrication of versatile and dynamically responsive LCP actuators.

Oxidative Upcycling of Polyethylene to Long Chain Diacid over Co-MCM-41 Catalyst.

Plastic pollution is an emerging global threat due to lack of effective methods for transforming waste plastics into useful resources. Here, we demonstrate a direct oxidative upcycling of polyethylene into high-value and high-volume long chain (C10-C20) saturated dicarboxylic acids in high carbon yield of 85.9% over cobalt-doped MCM-41 molecular sieves, in the absence of any solvent or precious metal catalyst. The distribution of the dicarboxylic acids can be controllably adjusted from short-chain (C4-C10) to long-chain ones (C10-C20) through changing cobalt loading of MCM-41 under nanoconfinement. Highly and sparsely dispersed cobalt along with confined space of mesoporous structure enables complete degradation of polyethylene and high selectivity of dicarboxylic acid in mild condition. So far, this is the first report on highly selective one-step preparation of long chain dicarboxylic acids. The approach provides an attractive solution to tackle plastic pollution and a promising alternative route to long chain diacids.

A One-Step Self-Flowering Method toward Programmable Ultrathin Porous Carbon-Based Materials for Microwave Absorption and Hydrogen Evolution.

Ultrathin 2D porous carbon-based materials offer numerous fascinating electrical, catalytic, and mechanical properties, which hold great promise in various applications. However, it remains a formidable challenge to fabricate these materials with tunable morphology and composition by a simple synthesis strategy. Here, a facile one-step self-flowering method without purification and harsh conditions is reported for large-scale fabrication of high-quality ultrathin (≈1.5 nm) N-doped porous carbon nanosheets (NPC) and their composites. It is demonstrated that the layered tannic/oxamide (TA/oxamide) hybrid is spontaneously blown, exfoliated, bloomed, in situ pore-formed, and aromatized during pyrolysis to form flower-like aggregated NPC. This universal one-step self-flowering system is compatible with various precursors to construct multiscale NPC-based composites (Ru@NPC, ZnO@NPC, MoS2 @NPC, Co@NPC, rGO@NPC, etc.). Notably, the programmable architecture enables NPC-based materials with excellent multifunctional performances, such as microwave absorption and hydrogen evolution. This work provides a facile, universal, scalable, and eco-friendly avenue to fabricate functional ultrathin porous carbon-based materials with programmability.

METTL3-stabilized lncRNA SNHG7 accelerates glycolysis in prostate cancer via SRSF1/c-Myc axis.

BACKGROUND: Long non-coding RNAs (lncRNAs) have emerged as novel players in cancer metabolism. lncRNA small nucleolar RNA host gene 7 (SNHG7) plays an oncogenic role in prostate cancer (PCa). However, the role and mechanism of SNHG7 in PCa metabolism remain largely undefined. METHODS: A cohort of 30 PCa tumors and their counterparts were collected. qRT-PCR was employed to detect target gene expression and RNA stability. CCK-8 assay was used to assess cell viability. N6-methyladenosine (m6A) level was measured by a commercial kit. Cell glycolysis was evaluated by measuring glucose uptake, lactate, ATP production and Extracellular acidification rate (ECAR). Bioinformatics analysis and RNA immunoprecipitation (RIP) assay were used to verify the interactions among SNHG7, serine/arginine-rich splicing factor 1 (SRSF1) and c-Myc. RESULTS: SNHG7 and c-Myc were highly expressed in PCa tissues and cells. Methyltransferase-like 3 (METTL3)-mediated m6A modification of SNHG7 and enhanced its stability. Silencing of SNHG7 suppressed proliferation and glycolysis in PCa cells. Mechanistically, SNHG7 regulated c-Myc via interacting with SRSF1. Gain- and loss-of function experiments revealed that SNHG7 promoted glycolysis via SRSF1/c-Myc axis in PC-3 and DU-145 cells. CONCLUSION: METTL3-stabilized lncRNA SNHG7 accelerates glycolysis in PCa via SRSF1/c-Myc axis and inspires the understanding of m6A roles in lncRNA metabolism and tumor progression.

Neighboring Molecular Engineering in Diels-Alder Chemistry Enabling Easily Recyclable Carbon Fiber Reinforced Composites.

Although a variety of dynamic covalent bonds have been successfully used in the development of diverse sustainable thermosetting polymers and their composites, solving the trade-off between recovery efficiency and comprehensive properties is still a major challenge. Herein, a "one-stone-two-birds" strategy of lower rotational energy barrier (Er ) phosphate-derived Diels-Alder (DA) cycloadditions was proposed for easily recyclable carbon fiber (CF)-reinforced epoxy resins (EPs) composites. In such a strategy, the phosphate spacer with lower Er accelerated the segmental mobility and dynamic DA exchange reaction for network rearrangement to achieve high-efficiency repairing, reprocessing of the EPs matrix and its composites and rapid nondestructive recycling of CF; meanwhile, incorporating phosphorus-based units especially reduced their fire hazards. The resulting materials simultaneously showed excellent thermal/mechanical properties, superb fire safety and facile recyclability, realizing the concept of recycling for high-performance thermosetting polymers and composites. This strategy is of great significance for understanding and enriching the molecular connotation of DA chemistry, making it potentially applicable to the design and development of a wide range of dynamic covalent adaptable materials toward practical cutting-edge-tech applications.

Dual Photo-Responsive Diphenylacetylene Enables PET In-Situ Upcycling with Reverse Enhanced UV-Resistance and Strength.

A novel in situ chemical upcycling strategy for plastic waste is proposed by the customized diphenylacetylene monomer with dual photo-response. That is, diphenylacetylene reactive monomers are in situ inserted into the macromolecular chain of polyethylene terephthalate (PET) plastics/fibers through one-pot transesterification of slight-depolymerization and re-polymerization. On the one hand, the diphenylacetylene group absorbs short-wave high-energy UV rays and then releases long-wave low-energy harmless fluorescence. On the other hand, the UV-induced photo-crosslinking reaction among diphenylacetylene groups produces extended π-conjugated structure, resulting in a red-shift (due to decreased HOMO-LUMO separation) in the UV absorption band and locked crosslink points between PET chains. Therefore, with increasing UV exposure time, the upcycled PET plastics exhibit reverse enhanced UV resistance and mechanical strength (superior to original performance), instead of serious UV-photodegradation and damaged performance. This upcycling strategy at oligomer-scale not only provides a new idea for traditional plastic recycling, but also solves the common problem of gradual degradation of polymer performance during use.

Bioinspired Optical Flexible Cellulose Nanocrystal Films with Strain-Adaptive Structural Coloration.

Recent advances of photonic crystals are driven to mechanical sensors and smart wearable devices; however, for chiral photonic cellulose nanocrystal (CNC) materials, vivid structural coloration and reversible mechanochromism like chameleon skin remain a big challenge. Here, we report a ternary co-assembly and post-UV-irradiation polymerization strategy to develop flexible and elastic CNC composite films, which, notably, have naked-eye-visible brilliant structural colors and stretching-induced color change covering a broad wavelength region at a moderate deformation (like skin). By adjusting the stretching, the film is designed as a smart skin to adapt to surrounding environments for camouflage. This work offers a universal strategy for constructing biomimic optically functional cellulose skins.

Photonic Cellulose Films with Vivid Structural Colors: Fabrication and Selectively Chemical Response.

Recent advances in structural-color cellulose nanocrystal (CNC) materials have been made toward chemical sensing applications; however, such materials lack sufficient color chroma for naked-eye observation, and their selective recognition to given chemicals as well as the corresponding mechanism has rarely been reported. Here, a dopamine-infiltration and post-polymerization approach is proposed to construct vivid structural-color composite films. The chiral nematic structure of CNC enables the structural coloration, while the strong light absorption of the polymeric co-phase, polydopamine (PDA) enhances the color chroma and visibility. By controlling the PDA amount, the composite films can detect organic solvents quantitatively and selectively via visible color changes. From the viewpoint of the compatibility and similitude principle, notably, a critical solubility parameter distance (R0) between PDA and "active" solvents is defined with a three-dimensional Hansen solubility sphere; this well constructs a rule for the sensing selectivity of the chemochromic composite films. The findings pave the foundation for the design of colorimetric sensors with specifically testing objects.

Autofluorescence of hydrogels without a fluorophore.

Fluorescent hydrogels have recently attracted great attention for medical diagnostics, bioimaging and environmental monitoring. However, additional phosphors or fluorophores are always required to label the hydrogels, and they suffer from marker bleaching, signal drifts, or information misrepresentation. Here we report autofluorescence that universally exists in carbonyl-containing hydrogels without any traditional fluorophore. The fluorescence is successfully employed to self-monitor the gelation process since the fluorescence signal is closely related to the internal structural change of the gels. The crosslinked structure is beneficial to the fluorescence efficiency. Specifically, the fluorescence intensity is amplified with decreasing water content of the gels. The system realizes aggregation-induced emission in a water-deficient environment. The fluorescence is quenched by the addition of some specific metal ions, which can realize the successfully erasure and rewriting of information under visible light and ultraviolet light respectively. We believe that the spontaneous fluorescence of a gel provides the most reliable basis for the detection of a gel structure and opens new prospects in the application of hydrogels.

Fire-Safe Polyesters Enabled by End-Group Capturing Chemistry.

Upon heating, polyesters decompose to small molecules and release flammable volatiles and toxic gases, primarily through chain scission of their ester linkages, and therefore exhibit poor fire-safety properties, thus restricting their applications. Reported herein is an end-group-capturing effect of (bis)oxazoline groups, generated from the thermal rearrangement of the N-(2-hydroxyphenyl)phthalimide (HPI) moiety which was incorporated into the polyester chain by copolymerization. These copolyesters, as a result, exhibit high efficiency in retarding decomposition by capturing the decomposed products, particularly for the carbonyl-terminated fragments, thus increasing the fire-safety properties, such as self-extinguishing, anti-dripping, and inhibiting heat release and smoke production. The successful application of this method in both semi-aromatic and aliphatic polyesters provide promising perspectives to designing versatile fire-safe polymers.

Self-complementary hydrogen-bond interactions of guanosine: a hub for constructing supra-amphiphilic polymers with controlled molecular structure and aggregate morphology.

A supra-amphiphilic polymer (SAP) with controlled molecular structures is constructed, in this work, via self-complementary hydrogen bonding of guanosine groups between a hydrophilic block, poly(N-isopropylacrylamide), and a hydrophobic block, poly(ε-caprolactone). By simply changing the mixing ratio of the guanosine-capped hydrophilic and hydrophobic blocks, a series of SAPs with tailored nanostructures are constructed, which can further self-assemble into different nano-aggregates in solution, including spheres, vesicles and large vesicle micelles. The thermo-induced phase transition of the hydrophilic block induces the fusion and aggregation of the nanoparticles into irregular particles upon heating, which further transform to large compound vesicles after cooling.

Human Umbilical Cord Wharton's Jelly Derived Mesenchymal Stromal Cells May Attenuate Sarcopenia in Aged Mice Induced by Hindlimb Suspension.

BACKGROUND Since the use of human umbilical cord Wharton's Jelly derived mesenchymal stromal cells (hWJ-MSCs) to treat sarcopenia has not been explored, we studied the effects of hWJ-MSCs in aged male C57BL/6J mice with sarcopenia induced by hindlimb suspension, and explored the potential mechanism. MATERIAL AND METHODS Hindlimb suspension was used to induce sarcopenia in 24-month-old C57BL/6J mice and green fluorescent protein-tagged hWJ-MSCs and controls were transplanted into mice via tail vein or local intramuscular injection. After hWJ-MSC transplantation, changes in whole body muscle strength and endurance, gastrocnemius muscle weight and myofiber cross-sectional area (CSA) were studied. Proliferation of skeletal muscle stem cell, apoptosis, and chronic inflammation were also investigated. RESULTS We demonstrated that whole body muscle strength and endurance, gastrocnemius muscle mass, and CSA were significantly increased in hWJ-MSC-transplanted mice than in controls (P<0.05). In hWJ-MSC-transplanted mice, apoptotic myonuclei was reduced, and BrdU and Pax-7 expression indices of gastrocnemius muscles were increased (P<0.05). Tumor necrosis factor (TNF)-α and interleukin (IL)-6 were downregulated, and IL-4 and IL-10 were upregulated (P<0.05). CONCLUSIONS hWJ-MSCs may ameliorate sarcopenia in aged male C57BL/6J mice induced by hindlimb suspension, and this may be via activation of resident skeletal muscle satellite cells, reduction of apoptosis, and less chronic inflammation.

Electrostatic wrapping of doxorubicin with curdlan to construct an efficient pH-responsive drug delivery system.

The development of environmentally responsive drug delivery systems for the treatment of cancer has attracted particular interest in recent years. However, the enhancement of drug loading capacity and realization of pH-responsive drug delivery remain challenging. Herein, we employ carboxymethyl curdlan as a hydrophilic carrier to wrap doxorubicin (DOX) directly via electrostatic interaction. The sizes of the formed nanoparticles can be simply tuned by changing their feeding ratios. In particular, the nanoparticles are highly stable in aqueous solution without size variation. In vitro drug release and cytotoxicity assays illustrate that this delivery system can release DOX differentially under various environmental conditions and transport it into cell nuclei efficiently, with comparable therapeutic effect to the free drug. These results suggest that the carrying of antitumor drugs by polysaccharide via electrostatic interaction is a simple but effective way to construct a pH-dependent drug delivery platform.

Design and Synthesis of PET-Based Copolyesters with Flame-Retardant and Antidripping Performance.

Poly(ethylene terephthalate) (PET) is a fiber-forming polymer with the largest output and widest usage. Its flame retardation is well-achieved via a mechanism of promoting the melt dripping while ignited. However, the melt dripping leads to secondary damage and an immediate empyrosis during fire. How to address the contradiction between the flame retardation and the melt-dripping behavior of PET via an inherent flame-retardant approach becomes a real challenge. This feature article highlights the design and synthesis of novel PET-based copolyesters with flame-retardant and antidripping performance. Three approaches are used to design these copolyesters: "ionic aggregation," "smart self-cross-linking," and "rearrangement at high temperatures." Some new conceptions are proposed accordingly. The synthesis, structure characterization, and properties of those copolyesters are discussed together with the ongoing challenges and limitations at this frontier.