Constructing Deep Traps to Achieve Excellent Dielectric Properties in Crystal-Based HfO2/PEI Nanocomposite Films with Ultralow Filler Loadings.

Mixing fillers featured with wide band gaps in polymers can effectively meet the requirement of higher energy storage densities. However, the fundamental relationship between the crystal structures of fillers and the dielectric properties of the corresponding nanocomposites is still unclear. Accordingly, we introduced ultralow contents of the synthesized cubic Hafnium dioxide (c-HfO2) or monoclinic Hafnium dioxide (m-HfO2) as deep traps into poly(ether imide) (PEI) to explore their effects on dielectric properties and the charge-blocking mechanism. m-HfO2/PEI showed better charge trapping due to the higher electron affinity and deeper trap energy. At room temperature, the 0.4 vol % m-HfO2/PEI maintains an ultralow dielectric loss of 0.008 while obtaining a dielectric constant twice that of pure PEI at 1 kHz, simultaneously outperforming in terms of leakage current density, breakdown strength (452 kV mm-1), discharge energy density (Ud, 5.03 J cm-3), charge-discharge efficiency (η, 92%), and dielectric thermal stability. At 125 °C, it exhibits a considerable Ud of 2.48 J cm-3 and a high η of 85% at 300 kV mm-1, surpassing the properties of pure PEI. This promising work opens up a new path for studying HfO2-derived dielectrics with unique crystal structures.

Functional-Group-Induced Single Quantum Well Dion-Jacobson 2D Perovskite for Efficient and Stable Inverted Perovskite Solar Cells.

In two-dimensional/three-dimensional (2D/3D) perovskite heterostructure, randomly distributed multiple quantum wells (QW) 2D perovskites are frequently generated, which are detrimental to carrier transport and structural stability. Here, the high quality 2D/3D perovskite heterostructure is constructed by fabricating functional-group-induced single QW Dion-Jacobson (DJ) 2D perovskites. The utilization of ─OCH3 in the precursor solution facilitates the formation of colloidal particles with uniform size, resulting in the production of a pure 2D DJ perovskite with an n value of 3. This strategy facilitates the improvement of 3D structural stability and expedites carrier transport. The resultant devices accomplish a power conversion efficiency of 25.26% (certified 25.04%) and 23.56% at a larger area (1 cm2 ) with negligible hysteresis. The devices maintain >96% and >89% of their initial efficiency after continuous maximum power point tracking under simulated AM1.5 illumination for 1300 h and under damp-heat conditions (85 °C and 85% RH) for 1010 h, respectively.

The Developed Wave Cancellation Theory Contributing to Understand Wave Absorption Mechanism of ZIF Derivatives with Controllable Electromagnetic Parameters.

How to better understand the influence of electromagnetic parameters on the absorbing properties of electromagnetic wave absorbers (EMAs) is an essential prerequisite for further synthesis and development of high-performance EMAs. In this work, an improved wave cancellation theory is used as a guiding principle to prepare N-doped carbon-coated cobalt nanoparticles (Co@NC) using ZIF-8@ZIF-67 as the precursor, thus enabling controllable electromagnetic parameters by regulating the conduction loss and dipole polarization ability. The Co@NC generated by pyrolysis at 700 °C under H2 atmosphere presents an optimized absorption performance. Benefiting from developed wave cancellation theory, the thickness of the film can be accurately adjusted so that the difference between the amplitude of the reflected and transmitted electromagnetic waves is only 0.001 and the phase difference is 180.05°, thus achieving a minimum reflection loss (RLmin (dB)) of -64.0 dB. Meanwhile, a maximum effective absorption bandwidth of 5.4 GHz is achieved simultaneously attributing to its most suitable electromagnetic parameters. Accordingly, the current research based on wave cancellation theory significantly contributes to understand the relationships between electromagnetic parameters and wave absorption properties, therefore providing a theoretical insight into the further development of high-performance EMAs.

Scalable co-cured polyimide/poly(p-phenylene benzobisoxazole) all-organic composites enabling improved energy storage density, low leakage current and long-term cycling stability.

The all-organic high-temperature polymer dielectrics with promising scale-up potential have witnessed much progress in the energy storage area, etc. However, the electron suppression trap mechanisms behind many all-organic dielectrics are still unclear, especially for high temperature resistant poly(p-phenylene benzobisoxazole) (PBO) polymers. To resolve this tough issue, we herein innovatively prepared PBO-based all-organic thin films containing sulfone-based polyimide (P(DSDA-ODA)) functioning as an electron trap phase using a facile and scalable co-curing method. The great linear dielectric properties of the prepared P(DSDA-ODA)/PBO films hold high dielectric thermal stability over the temperature range from 25 °C to 200 °C. The 60 wt% P(DSDA-ODA) systems yield the lowest leakage current (3.8 × 10-8 A cm-2). The tight structure and reduced leakage current enable an enhanced breakdown strength of 60 wt% P(DSDA-ODA)/PBO (470 kV mm-1), which is 1.7 times that of pure PBO. Meanwhile, it can reach 4.16 J cm-3 of energy density, which is 257% higher than that for pure PBO thin films while concurrently maintaining a long stable charge-discharge cycle (at least 5000 times) and high charge-discharge efficiency at 85.10%. Moreover, P(DSDA-ODA)/PBO still exhibits excellent energy storage performance at high temperature compared to PBO. This innovative strategy is further verified by replacing P(DSDA-ODA) with P(6FDA-ODA), and therefore lays a solid foundation for more investigation on scalable all-organic dielectrics.

Adjustable Plane Curvature of Covalent Organic Framework Enabling Outstanding Dielectric, Electret, and High-Temperature Processing Properties.

With the rapid development of integrated circuits towards miniaturization and complexity, there is an urgent need for materials with low dielectric constant/loss and high processing temperatures to effectively prevent signal delay and crosstalk. With high porosity, thermal stability, and easy structural modulation, covalent organic frameworks have great potential in the field of low dielectric materials. However, the optimization of dielectric properties by modulating the conjugated/plane curvature structure of covalent organic frameworks (COFs) has rarely been reported. Accordingly, we herein innovatively prepare COF films with adjustable planar curvature, hence possessing ultralow dielectric constant (1.9 at 1 kHz), ultralow dielectric loss at 1 kHz (0.0029 at room temperature, 0.0052 at 200 °C), high thermal decomposition temperature (5 % weight loss temperature, 473 °C) and good hydrophobicity (water contact angle, 105.3°). Also, to the best of our knowledge, we are the first to report that the resulting COF film enables high surface potential (≈320 V) for one week, attributing to its intrinsic high porosity, thus presenting great potential in electret applications. Accordingly, this innovative work provides a readily available and scalable idea to prepare materials with comprehensively excellent dielectric and electret properties as well as high processing temperatures simultaneously for advanced electronic device applications.

NiCo2 O4 /Hollow Mesoporous Carbon Nanosphere Hybrids Enabling Super-Hydrophobicity, Thermal Insulation, and Highly Efficient Microwave Absorption.

The combination of 2D magnetic nanosheets and mesoporous carbon with unique interfaces shows considerable prospects for microwave absorption (MA). However, traditional assembly procedures make it impossible to accurately manage the assembly of magnetic nanosheets in carbon matrices. Herein, a reverse strategy for preparing complex magnetic nanosheet cores inside carbon-based yolk-shell structures is developed. This innovative approach focuses on controlling the initial crystallite formation sites in a hydrothermal reaction as well as the inflow and in situ growth behavior of 2D NiCo-layered double hydroxide precursors based on the capillary force induced by hollow mesoporous carbon nanospheres. Accordingly, the as-prepared YS-CNC-2 absorber exhibits remarkable MA performances, with an optimal reflection loss as low as -60.30 dB at 2.5 mm and an effective absorption bandwidth of 5.20 GHz at 2.0 mm. The loss of electromagnetic waves (EMW) depends on natural resonance loss, dipole polarization relaxation, and multiple scattering behavior. On top of that, the functionalized super-hydrophobic MA coating is produced in spraying and curing processes utilizing YS-CNC-2 nanoparticles and fumed silica additives in the polydimethylsiloxane matrix. The excellent thermal insulation, self-cleaning capability, and durability in diverse solutions of the coating promise potential applications for military equipment in moist situations.

Achieving Excellent Dielectric and Energy Storage Performance in Core-Double-Shell-Structured Polyetherimide Nanocomposites.

The development of pulse power systems and electric power transmission systems urgently require the innovation of dielectric materials possessing high-temperature durability, high energy storage density, and efficient charge-discharge performance. This study introduces a core-double-shell-structured iron(II,III) oxide@barium titanate@silicon dioxide/polyetherimide (Fe3O4@BaTiO3@SiO2/PEI) nanocomposite, where the highly conductive Fe3O4 core provides the foundation for the formation of microcapacitor structures within the material. The inclusion of the ferroelectric ceramic BaTiO3 shell enhances the composite's polarization and interfacial polarization strength while impeding free charge transfer. The outer insulating SiO2 shell contributes excellent interface compatibility and charge isolation effects. With a filler content of 9 wt%, the Fe3O4@BaTiO3@SiO2/PEI nanocomposite achieves a dielectric constant of 10.6, a dielectric loss of 0.017, a high energy density of 5.82 J cm-3, and a charge-discharge efficiency (η) of 72%. The innovative aspect of this research is the design of nanoparticles with a core-double-shell structure and their PEI-based nanocomposites, effectively enhancing the dielectric and energy storage performance. This study provides new insights and experimental evidence for the design and development of high-performance dielectric materials, offering significant implications for the fields of electronic devices and energy storage.

Hierarchical and Orderly Surface Conductive Networks in Yolk-Shell Fe3 O4 @C@Co/N-Doped C Microspheres for Enhanced Microwave Absorption.

Constructing the adjustable surface conductive networks is an innovation that can achieve a balance between enhanced attenuation and impedance mismatch according to the microwave absorption mechanism. However, the traditional design strategies remain significant challenges in terms of rational selection and controlled growth of conductive components. Herein, a hierarchical construction strategy and quantitative construction technique are employed to introduce conductive metal-organic frameworks (MOFs) derivatives in the classic yolk-shell structure composed of electromagnetic components and the cavity for remarkable optimized performance. Specifically, the surface conductive networks obtained by carbonized ZIF-67 quantitative construction, together with the Fe3 O4 magnetic core and dielectric carbon layer linked by the cavity, achieve the cooperative enhancement of impedance matching optimization and synergistic attenuation in the Fe3 O4 @C@Co/N-Doped C (FCCNC) absorber. This interesting design is further verified by experimental results and simulation calculations. The products FCCNC-2 yield a distinguished minimum reflection loss of -66.39 dB and an exceptional effective absorption bandwidth of 6.49 GHz, indicating that moderate conduction excited via hierarchical and quantitative design can maximize the absorption capability. Furthermore, the proposed versatile methodology of surface assembly paves a new avenue to maximize beneficial conduction effect and manipulate microwave attenuation in MOFs derivatives.

Synergistic Modification of 2D Perovskite with Alternating Cations in the Interlayer Space and Multisite Ligand toward High-Performance Inverted Solar Cells.

The preparation of high-quality perovskite films is key to realize efficient and stable inverted perovskite solar cells. The trap-assisted nonradiative recombination at grain boundary (GB) and surface poses a serious challenge for fabricating high-quality perovskite films. Here, a synergistic modulation strategy of two-dimensional (2D) perovskite with alternating cations in the interlayer space (ACI) and multisite ligand 2-mercapto-1,3,4-thiadiazole (MTD) for fabricating high-quality methylammonium-free perovskite films is reported. The formation of ACI 2D perovskite promotes the nucleation of three-dimensional (3D) perovskites, suppresses the generation of yellow phase, and promotes the formation of black phase, leading to increased grain size and crystallinity. Due to the synergistic effect of ACI 2D perovskite and MTD, the defects at GBs and surface are healed simultaneously. The significantly inhibited nonradiative recombination enables realization of high-efficiency inverted devices with a fascinating power conversion efficiency (PCE) of 24.58%, which is one of the highest PCEs reported for inverted devices. The synergistically modified unsealed device demonstrates an excellent long-term ambient stability, retaining 90.5% of its initial PCE after 3000 h under a relative humidity of 30-40%. This work provides deep insights into minimizing nonradiative recombination losses through the rational synergistic engineering of GB and surface toward efficient and stable inverted devices.

Enhanced Interfacial and Dielectric Performance for Polyetherimide Nanocomposites through Tailoring Shell Polarities.

Polyimide (PI) and its derivative polyetherimide (PEI) have been widely investigated as promising candidates for dielectric energy storage due to their excellent intrinsic features. However, most of the current research for PI- or PEI-based dielectric nanocomposites only focuses on a certain polar group contained in a dianhydride monomer, while there are very few studies on exploring the effect of a series of polar groups derived from various dianhydride monomers on the dielectric properties of nanocomposites. To fill this gap, we herein fabricated and investigated a series of novel hyperbranched polyimides grafted on barium titanate nanoparticles (HBPI@BT) using different dianhydride monomers and their nanocomposites with the PEI matrix. The results showed that sophisticated hyperbranched structures effectively alleviated the incompatibility between fillers and the matrix, thus significantly improving the bonding energy of nanocomposites, especially for HBPI-S@BT/PEI (797.7 kJ/mol). The Ud of HBPI-S@BT/PEI reached 8.38 J/cm3, which is 3.3 times higher than that of pure PEI. The HBPI-F@BT/PEI nanocomposites achieved high breakdown strength (∼500 MV/m) and low dielectric loss (0.008) simultaneously. The dielectric constants of HBPI@BT/PEI nanocomposites remained at a stable level from 25 to 150 °C. This work provides us promising hyperbranched structured materials for potentially advanced dielectric applications such as field effect transistors.

Study of the radical polymerization mechanism and its application in the preparation of high-performance PMMA by reactive extrusion.

In this study, the mechanism of radical polymerization was further explored by pre-dissolving different polymers and studying the kinetics of the bulk polymerization of methyl methacrylate (MMA) under shear-free conditions. Based on the analysis of the conversion and absolute molecular weight, it was found that, contrary to the shearing effect, the inert polymer with viscosity was the key factor to preventing the mutual termination of radical active species and reducing the termination rate constant k t. Therefore, pre-dissolving the polymer could increase the polymerization rate and molecular weight of the system simultaneously, making the polymerization system enter the automatic acceleration zone faster and greatly reducing the generation of small molecular weight polymers, leading to a narrower molecular weight distribution. When the system entered the auto-acceleration zone, k t decreased rapidly and greatly and entered the second steady-state polymerization stage. Then, with the increase in the polymerization conversion, the molecular weight gradually increased, while the polymerization rate gradually decreased. In shear-free bulk polymerization systems, k t can be minimized and radical lifetimes maximized, but the polymerization system is at best a long-lived polymerization rather than a living polymerization. On this basis, by using MMA to pre-dissolve ultrahigh molecular weight PMMA and core-shell particles (CSR), the mechanical properties and heat resistance of the PMMA with pre-dissolved polymer obtained by reactive extrusion polymerization were better than for pure PMMA obtained under the same conditions. Compared with pure PMMA, the flexural strength and impact strength of PMMA with pre-dissolved CSR were up to 166.2% and 230.5%. With the same quality of CSR, the same two mechanical properties of the samples obtained by the blending method were just improved by 29.0% and 20.4%. This was closely related to the distribution of CSR in the pre-dissolved PMMA-CSR matrix with a distribution of spherical single particles 200-300 nm in diameter, which enabled PMMA-CSR to exhibit a high degree of transparency. This one-step process for realizing PMMA polymerization and high performance shows extremely high industrial application prospects.

Application of Natural Molecules in Efficient and Stable Perovskite Solar Cells.

Perovskite solar cells (PSCs), one of the most promising photovoltaic technologies, have been widely studied due to their high power conversion efficiency (PCE), low cost, and solution processability. The architecture of PSCs determines that high PCE and stability are highly dependent on each layer and the related interface, where nonradiative recombination occurs. Conventional synthetic chemical materials as modifiers have disadvantages of being toxic and costly. Natural molecules with advantages of low cost, biocompatibility, and being eco-friendly, and have improved PCE and stability by modifying both functional layers and interface. In this review, we discuss the roles of natural molecules on PSCs devices in terms of the perovskite active layer, interface, carrier transport layers (CTLs), and substrate. Finally, the summary and outlook for the future development of natural molecule-modified PSCs are also addressed.

Induced Crystallization-Controllable Nanoarchitectonics of 3D-Ordered Hierarchical Macroporous Co@N-Doped Carbon Frameworks for Enhanced Microwave Absorption.

The construction of ordered hierarchical porous structures in metal-organic frameworks (MOFs) and their derivatives is highly promising to meet the low-density and high-performance demands of microwave absorption materials. However, traditional methods based on sacrificial templates or corrosive agents inevitably suffer from the collapse of the microporous framework and the accumulation of nanoparticles during the carbonization transformation, resulting in the deteriorating impedance match, which greatly limits the incident and attenuation of microwaves. Herein, an induced crystallization and controllable nanoarchitectonics strategy is employed to replace traditional growing-etching methods and successfully synthesize carbonized 3D-ordered macroporous Co@N-doped carbon (3DOM Co@NDC) based on the 3D-ordered template. The obtained 3D-ordered macroporous structure ensures the stable growth of hybrid carbon frameworks and CoC nanoparticles without collapse, preserves abundant interfaces for both the incident and attenuation performance, so as to significantly improve the impedance matching and absorption properties compared to conventional MOFs derivatives. The minimum reflection loss of 3DOM Co@NDC is -57.36 dB at the thickness of 1.9 mm, and the effective bandwidth is 7.36 GHz at 1.6 mm. Moreover, the innovative strategy to prepare 3D-ordered hierarchical macroporous structures opens up a new avenue for advanced MOFs-derived absorbers with excellent performance.

Stabilizing Buried Interface via Synergistic Effect of Fluorine and Sulfonyl Functional Groups Toward Efficient and Stable Perovskite Solar Cells.

The interfacial defects and energy barrier are main reasons for interfacial nonradiative recombination. In addition, poor perovskite crystallization and incomplete conversion of PbI2 to perovskite restrict further enhancement of the photovoltaic performance of the devices using sequential deposition. Herein, a buried interface stabilization strategy that relies on the synergy of fluorine (F) and sulfonyl (S=O) functional groups is proposed. A series of potassium salts containing halide and non-halogen anions are employed to modify SnO2/perovskite buried interface. Multiple chemical bonds including hydrogen bond, coordination bond and ionic bond are realized, which strengthens interfacial contact and defect passivation effect. The chemical interaction between modification molecules and perovskite along with SnO2 heightens incessantly as the number of S=O and F augments. The chemical interaction strength between modifiers and perovskite as well as SnO2 gradually increases with the increase in the number of S=O and F. The defect passivation effect is positively correlated with the chemical interaction strength. The crystallization kinetics is regulated through the compromise between chemical interaction strength and wettability of substrates. Compared with Cl-, all non-halogen anions perform better in crystallization optimization, energy band regulation and defect passivation. The device with potassium bis (fluorosulfonyl) imide achieves a tempting efficiency of 24.17%.

Radical reaction extrusion copolymerization mechanism of MMA and N-phenylmaleimide and properties of products.

Using the method of bulk reactive extrusion radical copolymerization, N-phenyl maleimide (N-PMI) and styrene (St) and methyl methacrylate (MMA) were copolymerized. Through multi-detection gel permeation chromatography, bulk copolymerization kinetic analysis, UV-Vis spectroscopy, elemental analysis, and 1H NMR and 13C NMR analysis, it was found that, contrary to the classical free radical copolymerization theory, N-PMI and MMA could not only achieve copolymerization, but could even reach the level of azeotropic copolymerization. The factor that caused this change turned out to be the viscosity of the system. Secondly, through DSC, TG and GC-MS analysis, it was found that N-PMI units were randomly inserted into the molecular chain of PMMA, which greatly improved the stiffness of its molecular segments and the T g of the copolymer; at the same time, the insertion of N-PMI units also very effectively blocked the zipper-style de-end group degradation that often occurs in PMMA. When the mass content of the N-PMI copolymer reached 10%, the T g, initial degradation temperature and semi-degradation temperature of the copolymer increased by 19 °C, 58 °C and 47 °C, respectively. In addition, St, N-PMI can also significantly improve the processing fluidity of the PMMA copolymer, and after St participates were introduced in the copolymerization, the melt flow rate can be increased by 3.5 times. Furthermore, the copolymer not only had good mechanical properties and transparency, but also had excellent antibacterial properties against E. coli and S. aureus with only the effect of trace residual N-PMI in the copolymer. This provides an excellent reference for the preparation of antibacterial PMMA with high heat resistance, good mechanical properties and high transparency.

Morphology-Controlled Fabrication Strategy of Hollow Mesoporous Carbon Spheres@f-Fe2O3 for Microwave Absorption and Infrared Stealth.

The design and development of radar--infrared compatible stealth materials are challenging in the field of broadband absorption due to the contradiction of stealth requirements and mechanisms in different frequency bands. However, hollow structures show great promise for multispectral stealth because they can lengthen the attenuation path of electromagnetic waves (EMWs) for microwave absorption, interrupt the continuity of heat-transport channels, and lower the thermal conductivity to realize infrared stealth. Here, a new morphological fabrication strategy has been developed to efficiently prepare compatible stealth nanomaterials. In a specific hydrothermal process, the confined growth of flake α-Fe2O3 (f-Fe2O3) outside of hollow mesoporous carbon spheres (HMCS) is achieved using NH3·H2O as a shape-controlled reagent. The introduction of f-Fe2O3 helps to lower infrared emissivity and improve high-frequency impedance matching, which depends on the stable dielectric property of the specific flake shape. Moreover, the size of f-Fe2O3 can be regulated by changing the constituent proportion in the hydrothermal suspension to obtain excellent performance. The minimum reflection loss (RL) of the HMCS@f-Fe2O3-6 composite is -34.16 dB at 2.4 mm, and the effective absorption bandwidth (EAB) reaches 4.8 GHz. Furthermore, the lowest emissivities of the HMCS@f-Fe2O3-6-20 wt %/polyetherimide (PEI) film in the 3-5 and 8-14 µm infrared wavebands are 0.212 and 0.508, respectively. These discoveries may pave the way for the development of radar-infrared compatible stealth materials from the perspective of microstructural design.

Stabilizing Perovskite Precursor by Synergy of Functional Groups for NiOx -Based Inverted Solar Cells with 23.5 % Efficiency.

Perovskite solar cells suffer from poor reproducibility due to the degradation of perovskite precursor solution. Herein, we report an effective precursor stabilization strategy via incorporating 3-hydrazinobenzoic acid (3-HBA) containing carboxyl (-COOH) and hydrazine (-NHNH2 ) functional groups as stabilizer. The oxidation of I- , deprotonation of organic cations and amine-cation reaction are the main causes of the degradation of mixed organic cation perovskite precursor solution. The -NHNH2 can reduce I2 defects back to I- and thus suppress the oxidation of I- , while the H+ generated by -COOH can inhibit the deprotonation of organic cations and subsequent amine-cation reaction. The above degradation reactions are simultaneously inhibited by the synergy of functional groups. The inverted device achieves an efficiency of 23.5 % (certified efficiency of 23.3 %) with an excellent operational stability, retaining 94 % of the initial efficiency after maximum power point tracking for 601 hours.

Antibacterial Mechanism of N-PMI and the Characteristics of PMMA-Co-N-PMI Copolymer.

Aiming at the excellent killing effect of N-phenylmaleimide (N-PMI) on microorganisms, this article used structural simulation analysis, fluorescence analysis, confocal laser scanning microscope and SEM to find that the double bond in N-PMI could interact with the sulfur groups in the membrane protein, changing its conformation, rupturing the plasma membrane of the cell, leaking the contents, and ultimately causing the death of the microorganisms. Therefore, once the double bond participated in the polymerization, N-PMI lost its antimicrobial function. N-PMI could achieve azeotropic copolymerization with MMA through reactive extrusion polymerization. N-PMI with a content of 5 % can be evenly inserted into the PMMA chain segment during the copolymerization reaction, thereby increasing the Tg of pure PMMA by up to 15 °C, which provided the PMMA-co-PMI copolymer with resistance to boiling water sterilization advantageous conditions. In addition, N-PMI with a content of 5 % has little effect on the transparency of PMMA after participating in the copolymerization. Moreover, the trace amount of residual N-PMI made the material have excellent antimicrobial function, and the bacteriostatic zone is extremely small, which provided an excellent guarantee for the safety and durability of the material. As a medical biological material, the PMMA-co-PMI copolymer has a good industrialization application prospects.

Effect of curing reaction types on the structures and properties of acetylene-containing thermosets: towards optimization of curing procedure.

High-temperature thermosets are usually prepared from resins containing alkynyl groups, and their properties depend much upon the curing process containing various types of curing reactions. However, how the curing process affects the properties remains unclear due to the complicated curing reactions. We used molecular dynamics simulations to investigate the effect of curing reaction types, including cyclotrimerization, Diels-Alder reaction, and radical reaction, on the structures and properties of imide oligomers terminated with alkynyl groups. The results show that the cycloadditions such as cyclotrimerization and Diels-Alder reaction endow the thermosets with rigid structures and high moduli. Compared with the cycloadditions, the radical reaction enables the formation of flexible cured structures, which can enhance the toughness of thermosets. The differences in thermal and mechanical properties caused by different curing types were elucidated by the relaxation processes of fragments in these cured systems and were explained by the variation of torsion energy in different curing forms. As this work aims to optimize the curing procedure to obtain high-performance resins with desired properties, different curing procedures were finally designed according to the theoretical studies, and the obtained cured polymers show significant differences in the properties from different curing ways. The results can guide the preparation of desired thermosetting resins by tuning the curing procedure.

Efficient enzyme-activated therapy based on the different locations of protein and prodrug in nanoMOFs.

Enzyme-activated prodrug therapy (EAPT) is an effective cancer treatment strategy able to transport non-toxic prodrugs and subsequently convert them into drugs at specific times and locations. However, due to the limitation of easy biodegradability and the membrane-impermeable characteristic of exogenous enzymes, there is a need to exploit suitable carriers for the effective protection and simultaneous delivery of activating enzymes into cancer cells. Herein, hierarchically porous MOFs were employed for the loading of enzyme and prodrug in a single nanocarrier thanks to their different cavity sizes. The simple loading process allows entrapping of horseradish peroxidase (HRP) and a monocarboxyl-containing indole-3-acetic acid (IAA) prodrug with high loading capacities in different spaces, which keeps the catalytic activity of the enzyme perfectly intact and avoids the premature activation of the prodrug. The encapsulated HRP and IAA exhibit sustained and synchronized release behaviors. Compared to the native HRP enzyme, the current MOF nanocarriers not only facilitate enzyme delivery into cellular lysosomes and subsequent endosomal escape, but also effectively release enzyme and prodrug in the intracellular environment within 48 h. Eventually, HRP and IAA loaded MOF nanocarriers cause significant cell death with a low IC50 of 4.2 mg L-1, while the IAA prodrug alone is non-toxic even at high concentrations. Thus, hierarchically porous MOFs might offer a promising platform for EAPT with a highly consistent spatiotemporal distribution of enzymes and prodrugs in target tissues.