The solvent-driven soft actuators with response to solvent with visible deformation gained considerable attention for their application in many fields such as VOC monitoring and soft robot. Inspired by the methanol and humidity driven MOF (Metal-Organic framework)/polymer composite actuators based on classic flexible MOFs, two multiple solvents-driven flexible MOF/polymer soft actuators based on an interpenetrated MOF and a pillared-layer MOF (MOF-Cd/PVDF and DUT-8(Ni)/PVDF), have been successfully fabricated. Due to the synergistic effect of PVDF matrix and MOF fillers, both unfixed MOF-Cd/PVDF and DUT-8(Ni)/PVDF asymmetric membranes exhibit a biaxial alternation bending mode which is different from the previous MOF/polymer composite materials. The MOF-Cd/PVDF and DUT-8(Ni)/PVDF asymmetric membranes can respond to the vapor of multiple organic solvents and diluted ammonia, especially relatively fast and large bending deformation to acetone, tetrahydrofuran, pyridine, acrylonitrile and ethylacetate. Specifically, due to its wider aperture distribution range and larger pore size, the MOF-Cd/PVDF can respond to tetrahydrofuran vapor with a quick bending deformation (similar to 3 s) and a maximum folding angle of 91 degrees, and also exhibit a fast recovery (similar to 3 s) at mild conditions. In addition, some simple devices including a multiple solvent-driven quatrefoil, and a tetrahydrofuran/acetone-driven smart box were designed based on above two MOF/polymer asymmetric membranes. This work is the first example of MOF/polymer actuators which apply interpenetrated MOF and involve the synergy between the flexible MOF and the polymer matrix. This work may open up a new application field for MOFs, and also provides a new perspective for the MOFs/polymer smart materials.

This study synthesizes two highly water-soluble copolymers, p(SA-co-SMAS) and p(SA-co-SMAS-co-AMPS) using sodium alginate (SA), sodium 2-methylprop-2-ene-1-sulfonate (SMAS), and 2-acrylamido-2-methylpropane sulfonic acid (AMPS, with or without addition) as precursors. Under ball milling, these copolymers are blended with aluminum sulfate and glass fibers to produce two series of cement admixtures. Compared to systems without admixtures or with pure aluminum sulfate as sole admixture, the admixture obtained from p(SA-co-SMAS) and aluminum sulfate significantly shortens the initial setting time (4.47 vs. 33.59 and 29.51 min) and final setting time (8.46 vs. 45.26 and 35.12 min), while markedly improving compressive strength (9.2 vs. 3.5 and 4.3 MPa) and flexural strength (3.5 vs. 1.0 and 1.1 MPa). This enhancement is attributed to the formation of a unique boehmite (AlO(OH)) phase in synthesized admixture, which rapidly reacts with tricalcium silicate, gypsum, and water in cement to form ettringite (Ca6Al2(SO4)3(OH)12·26H2O). The ettringite interlocks with the two-dimensional C–S–H gel, creating a stable three-dimensional network. Further blending this admixture with 200-mesh glass fibers yields a new admixture containing Al4SO4(OH)10·36H2O. Compared to boehmite, this phase further reduces setting times and increases average compressive strength (10.2 vs. 9.2 MPa). The admixture derived from p(SA-co-SMAS-co-AMPS) and aluminum sulfate shows even better performance: setting times are further shortened and flexural strength is significantly enhanced, owing to the presence of the more effective Al4SO4(OH)10·36H2O phase. Incorporating 200-mesh glass fibers into this system results in the shortest setting times (initial: 2.24 min, final: 5.73 min) and an excellent 24 h compressive strength (9.4 MPa), likely due to a unique and unexpected pore-filling effect. In contrast to conventional uses of sodium alginate as a retarder, glass fibers as mere reinforcements, and aluminum sulfate as a strength-impairing accelerator, this work demonstrates a synergistic strategy, which enables an ultra-rapid and high-strength cement setting process, offering highly significant scientific and practical value.

Baeyer-Villiger oxidation is an efficient method of synthesizing value-added esters or lactones by inserting of an oxygen atom into ketones. Inexpensive bimetallic MIL-100(Fe,Cu) catalysts are prepared with a green and mild experimental technique. The catalysts have been comprehensively characterized and tested their catalytic performance of aerobic Baeyer-Villiger oxidation. Screening experiments are conducted to evaluate the effects of reaction time, temperature, the molar ratio of benzaldehyde to cyclohexanone, and catalyst mass on the oxidation of cyclohexanone. Surprisingly, it is observed that a catalyst in a ratio of 6:1 (Fe to Cu) exhibits high catalytic activity (99 % cyclohexanone conversion and 99 % epsilon-caprolactone yield). The scope of substrates indicates that the screened catalyst demonstrates moderate to high activity for five- and six-membered cyclic ketones. Furthermore, the prepared catalyst is thermally stable and exhibits significant recycling activity (>96 %). The reaction mechanism and the role of the catalyst are clarified through computational study. The catalyst can first trap and activate O-2 to oxidize benzaldehyde towards benzoyl peroxy acid. Significantly, the high catalytic activity would be attributed to the copper-modulated morphology of the catalyst. The activation energy is estimated to be 19 kcal/mol in the kinetic experiments. Consequently, we have developed an inexpensive MIL-100(Fe,Cu) catalyst via a green synthetic method for an aerobic Baeyer-Villiger oxidation of cyclic ketones to lactones.

Potassium hexatitanate whiskers are prepared and characterized in this study. The reinforcement of polyethylene with potassium hexatitanate whiskers is also investigated. The potassium hexatitanate whiskers are prepared through the calcination of TiO2 and K2CO3 at 1000 °C. It is determined that a polyvinylpyrrolidone additive is crucial for the formation of slender rod-like structures with smooth and flat surfaces and a high length-to-diameter ratio. For the surface modification of the whiskers, γ-aminopropyl triethoxysilane has been identified as the most effective coupling agent for enhancing mechanical properties. The whiskers have little change in shape after surface modification, and the majority of the whiskers still retain a considerable length-to-diameter ratio. The results of mechanical tests indicate that the tensile strength and the modulus of elasticity, as well as the shear strength and the shear elasticity, are enhanced to some extent. The tensile strength and the modulus of elasticity increase by 18.6% and 3.6%, respectively. The modified polyethylene composites show enhanced softness and elasticity. The elongation at the break for the prepared PE/PHT-2-1 composites increases significantly to 38.1%, significantly exceeding that of unfilled polyethylene (6.84%). Nevertheless, a suitable method is established for reinforcing thermoplastic polymers using inexpensive potassium hexatitanate whiskers.

Environment and health are two of the main concerns in the 21st century, driving increased demands for personalized monitoring technologies. Among these, micro- and nano- electromechanical systems (M/NEMS)-based resonant gravimetric gas sensors have garnered significant research attention because of their potential for continuous, real-time, and in-site monitoring of air pollutions and breath biomarkers for human disease diagnostics. Resonant gravimetric gas sensors combine mechanics, chemistry, and materials, with challenges in achieving stable, repeatable, and durable sensing performances because of the instability and susceptible feature of the sensing materials. This review provides a comprehensive summary of the state-of-the-art resonant gravimetric gas sensors. The fundamental mechanisms of these sensors, as well as the most commonly used sensing materials and functionalization techniques, are introduced. Recent progress in strategies to enhance the sensor’s key performance metrics, such as selectivity, sensitivity, limit of detection, repeatability, and response time, are discussed in detail. Further, we summarize recent advances in the applications of resonant gravimetric gas sensors in environmental pollution detection and healthcare monitoring. Finally, the challenges and perspectives of this type of gas sensor are discussed. This review is helpful for researchers interested in developing resonant gravimetric gas sensors and in tackling the remaining challenges to accelerate the realization of this class of sensors toward practical applications.

Two hydrophilic copolymers containing functional groups such as carboxyl, amido, and sulfonic acid are synthesized using ammonium persulfate-catalyzed free radical polymerization in water. Aluminum sulfate is then introduced, resulting in two polymer complexes that exhibit reduced cement setting times (initial, 1.16–2.44 min; final, 2.02–3.14 min) and improved compressive (24 h, 5.81–7.25 MPa) and flexural (24 h, 2.80–2.99 MPa) strengths compared to pure aluminum sulfate-facilitated cementing (initial, 19.11 min; final, 37.05 min; compressive, 24 h, 5.51 MPa; flexural, 24 h, 2.56 MPa). Following this, ball-milled illite powder is added, and the resulting admixtures further display slightly prolonged setting times (initial, 2.35–2.99 vs. 1.16–2.44 min; final, 3.98–4.35 vs. 2.02–3.14 min), along with comparable compressive strengths (5.85–7.11 vs. 5.81–7.25 MPa) and enhanced flexural strengths (3.92–5.83 vs. 2.80–2.99 MPa). Notably, a unique adhesive pozzolanic clinker, Ca54MgAl2Si16O90 (54CaO·MgO·Al2O3·16SiO2), emerges in the presence of illite-based admixtures, contributing to the mechanical strength development of the hydrated mortars. Although illite itself is hydrophobic, the coating of ball-milled illite powder with aluminum sulfate and copolymers facilitates its dispersion into the gaps and pores of the cement matrix during setting, thereby increasing the flexural strength. This work presents an interesting approach to utilizing illite materials in cement applications, which is significant for reducing CO2 emissions during cement production and use.

This study develops a series of functional admixtures for ordinary Portland cement based on a synthesized watersoluble terpolymer and its ball-milled composites with aluminum sulfate. The foundational admixture significantly accelerates cement setting, achieving an initial setting time of 4.33 min and a final setting time of 7.98 min, performance that exceeds the Chinese National Standard GB/T 35159-2017 requirements for flashsetting admixtures (which specify <= 5 min for initial setting and <= 12 min for final setting), while delivering a 24-hour compressive strength of 5.0 MPa and flexural strength of 1.6 MPa. The acceleration mechanism is attributed to the in-situ formation of the active intermediate (H3O)Al3(SO4)2(OH)6. Incorporating potassium titanate whiskers-A3 derived from anatase (TiO2) and A4 from metatitanic acid (TiO2 & sdot;H2O)-forms microcapsule-structured composites that further enhance performance. The A3-based composite reduces initial setting time to 3.83 min and final setting time to 7.10 min, while significantly improving mechanical strength, achieving a 24-hour compressive strength of 6.8 MPa that nearly meets the GB/T 35159-2017 standard requirement of >= 7.0 MPa at 24 h. A4-based whiskers provide comparable acceleration and demonstrate superior long-term flexural strength, reaching 5.1 MPa at 28 days. Mechanistic analysis reveals aluminum species drive rapid setting while whiskers enhance strength through distinctive phase transformations during hydration. Furthermore, 3-aminopropyltriethoxysilane-modified whiskers (both A3 and A4) produce admixtures that function as potent set retarders while simultaneously increasing 24-hour compressive and flexural strengths by 113 % and 91 % respectively compared to plain cement mortar, demonstrating exceptional superplasticizer characteristics. A key finding is the whisker-specific optimization strategy: silane pretreatment benefits A3 for achieving both accelerated setting and high strength, whereas unmodified A4 performs better in the same application. This work elucidates the design principles and mechanisms of tunable multifunctional cement admixtures, establishing strategic pathways for developing advanced construction materials suitable for applications ranging from shotcrete to oil well cementing.

This study introduces an innovative method for synthesizing multifunctional water-retaining agents via ammonium persulfate-initiated alkaline copolymerization of sodium humate with diverse functional components. The resulting materials exhibit exceptional and reproducible water/saline absorbing capabilities, outstanding water retention performance, and remarkable UV resistance. Structural characterization demonstrates that sodium humate's graphite backbone can be either preserved or modified depending on the copolymerized components, with polyvinyl alcohol (37.41-93.82 g g-1) and polyvinyl pyrrolidone (39.23-97.66 g g-1) composites showing particularly superior water absorption properties over 18 recycling cycles. A significant discovery is the concurrent formation of ammonium nitranilate, a high-energy-density salt, whose production from humic acid not only confirms Stevenson's structural model featuring quinone moieties but also offers an economical alternative to conventional chloranil-based synthesis that requires hazardous chlorine gas and expensive precursors. This work thus accomplishes dual breakthroughs: developing high-performance irrigation materials for arid regions while establishing a highly effective valorization pathway for humic acid to produce valuable energetic compounds.

This study presents a new ternary copolymer synthesized via aqueous free-radical polymerization from sodium humate, sodium 2-methylprop-2-ene-1-sulfonate (SMAS), and 2-acrylamido-2-methylpropane sulfonic acid (AMPS). The resulting highly water-soluble, three-dimensional porous copolymer is complexed with aluminum sulfate to form a composite admixture containing AlO(OH), which acts as a highly effective accelerator for cement hydration. This system significantly shortens the initial and final setting times to averages of 2.62 min and 4.53 min, respectively, and enhances early-age mechanical strength (1.7 MPa compressive, 1.4 MPa flexural at 6 h). These improvements are correlated with the formation of key crystalline phases, including Al2Si2O5(OH)4 and Ca3Al2O6·xH2O gel. Incorporation of 50-mesh carbon fibers further reduces setting times (2.21 min initial, 3.93 min final) and increases 24 h strength (5.2 MPa compressive, 2.7 MPa flexural), despite a slight reduction in early strength (at 6 h). In contrast, 200-mesh carbon fibers extend the initial setting time and diminish early strength, associated with the formation of less effective gel phases such as Ca3Al2O6·xH2O, (CaO)x(Al2O3)11, and Ca4Al2O7·xH2O. Among these, the Al2Si2O5(OH)4 phase demonstrates superior performance, while finer carbon fibers show limited effectiveness in bridging hydration products. Conventionally employed as retarders or reinforcing agents, humate-based polymers and carbon fibers are shown here to function as dual-functional admixtures—serving as efficient setting accelerators while enhancing mechanical properties through tailored material design. This strategy offers a promising pathway for developing advanced multifunctional cement admixtures.

This study develops a series of functional admixtures for ordinary Portland cement based on a synthesized water-soluble terpolymer and its ball-milled composites with aluminum sulfate. The foundational admixture significantly accelerates cement setting, achieving an initial setting time of 4.33 min and a final setting time of 7.98 min, performance that exceeds the Chinese National Standard GB/T 35159–2017 requirements for flash-setting admixtures (which specify ≤5 min for initial setting and ≤12 min for final setting), while delivering a 24-hour compressive strength of 5.0 MPa and flexural strength of 1.6 MPa. The acceleration mechanism is attributed to the in-situ formation of the active intermediate (H3O)Al3(SO4)2(OH)6. Incorporating potassium titanate whiskers—A3 derived from anatase (TiO2) and A4 from metatitanic acid (TiO2·H2O)—forms microcapsule-structured composites that further enhance performance. The A3-based composite reduces initial setting time to 3.83 min and final setting time to 7.10 min, while significantly improving mechanical strength, achieving a 24-hour compressive strength of 6.8 MPa that nearly meets the GB/T 35159–2017 standard requirement of ≥ 7.0 MPa at 24 h. A4-based whiskers provide comparable acceleration and demonstrate superior long-term flexural strength, reaching 5.1 MPa at 28 days. Mechanistic analysis reveals aluminum species drive rapid setting while whiskers enhance strength through distinctive phase transformations during hydration. Furthermore, 3-aminopropyltriethoxysilane-modified whiskers (both A3 and A4) produce admixtures that function as potent set retarders while simultaneously increasing 24-hour compressive and flexural strengths by 113 % and 91 % respectively compared to plain cement mortar, demonstrating exceptional superplasticizer characteristics. A key finding is the whisker-specific optimization strategy: silane pretreatment benefits A3 for achieving both accelerated setting and high strength, whereas unmodified A4 performs better in the same application. This work elucidates the design principles and mechanisms of tunable multifunctional cement admixtures, establishing strategic pathways for developing advanced construction materials suitable for applications ranging from shotcrete to oil well cementing.

Two hydrophilic copolymers containing functional groups such as carboxyl, amido, and sulfonic acid are synthesized using ammonium persulfate-catalyzed free radical polymerization in water. Aluminum sulfate is then introduced, resulting in two polymer complexes that exhibit reduced cement setting times (initial, 1.16-2.44 min; final, 2.02-3.14 min) and improved compressive (24 h, 5.81-7.25 MPa) and flexural (24 h, 2.80-2.99 MPa) strengths compared to pure aluminum sulfate-facilitated cementing (initial, 19.11 min; final, 37.05 min; compressive, 24 h, 5.51 MPa; flexural, 24 h, 2.56 MPa). Following this, ball-milled illite powder is added, and the resulting admixtures further display slightly prolonged setting times (initial, 2.35-2.99 vs. 1.16-2.44 min; final, 3.98-4.35 vs. 2.02-3.14 min), along with comparable compressive strengths (5.85-7.11 vs. 5.81-7.25 MPa) and enhanced flexural strengths (3.92-5.83 vs. 2.80-2.99 MPa). Notably, a unique adhesive pozzolanic clinker, Ca54MgAl2Si16O90 (54CaOMgOAl2O316SiO2), emerges in the presence of illite-based admixtures, contributing to the mechanical strength development of the hydrated mortars. Although illite itself is hydrophobic, the coating of ball-milled illite powder with aluminum sulfate and copolymers facilitates its dispersion into the gaps and pores of the cement matrix during setting, thereby increasing the flexural strength. This work presents an interesting approach to utilizing illite materials in cement applications, which is significant for reducing CO2 emissions during cement production and use.

A water-soluble ternary copolymer bearing carboxyl, sulfonic, and amide functional groups was synthesized using ammonium persulfate-catalyzed free radical polymerization in water, resulting in high monomer conversion. This copolymer was then complexed with aluminum sulfate, forming an admixture containing Al(SO4)(OH)·5H2O, which was subsequently combined with silica gel. Characterization revealed that the synthesized copolymer formed a large, thin membrane that covered both the aluminum compounds and the silica gel blocks. The introduction of this complex admixture, combining the copolymer and aluminum sulfate, not only reduced the setting times of the cement paste but also enhanced the mechanical strengths of the mortar compared to using aluminum sulfate alone. The complex admixture led to the formation of katoite, metajennite, and C3A (tricalcium aluminate) in the mortar, demonstrating significant linking effects, whereas pure aluminum sulfate could not completely transform C3S within 24 h. Further addition of silica gel to the complex admixture further shortened the setting times of the paste, slightly reduced compressive strength, but improved flexural strength compared to the initial complex admixture. The silicon components appeared to fill the micropores and mesopores of the mortar, accelerating cement setting and enhancing flexural strength, while slightly decreasing compressive strength. This study contributed to the development of new cementing accelerators with improved hardening properties.

A series of Fe–Ba mixed oxides, including a pure Fe-containing sample as a reference, have been synthesized via a sol–gel process using Fe3+ or Fe2+ salts and BaSO4 as raw materials, with Pluronic P123 serving as a template. These oxides have been thoroughly characterized and subsequently utilized as catalysts for the chlorination of various organic molecules. Commercial hydrochloric acid, known for its relative safety, and environmentally friendly aqueous hydrogen peroxide were employed as the chlorine source and oxidant, respectively. The pure Fe-containing catalyst displays excellent thermal stability between 600 and 800 °C and exhibited moderate to high conversions in the chlorination of toluene, benzene, and tert-butyl hydroperoxide, with remarkable ortho-selectivity in chlorination of toluene. The combination of Fe3+ salt with BaSO4 in the sol–gel process results in a Fe–Ba mixed oxide catalyst composed of BaO2, BaFe4O7, and Fe2O3, significantly enhancing the chlorination activity compared to that displayed by the pure Fe catalyst. Notably, the chlorination of tert-butyl hydroperoxide (TBHP) does not require additional oxidants such as H2O2, and involves both electrophilic substitution and nucleophilic addition. Notably, the chlorination of bromobenzene yields chlorobenzene as the sole product, a transformation that has not been previously reported. Overall, this catalytic chlorination system holds promise for advancing the chlorination industry and enhancing pharmaceutical production.

In order to improve the limited compatibility of existing polymer/ceramic dielectric composites and further enhance the energy storage density, MOF/polymer composite dielectrics have been explored, which exhibit good compatibility to the polymer matrix from abundant organic groups of the inorganic–organic hybrid metal-organic framework (MOF) fillers. However, they still lack a clear composition–structure–property rule, and the precise design of MOF fillers and polymer matrix becomes a prominent problem in these composites due to the diversity of the metal ions and the organic groups. Thus, in this paper, we present a series of formic acid MOFs/polylactic acid dielectric composites in which ferroelectric formic acid MOFs, namely PDLLA/[NH[Formula: see text](CH[Formula: see text])[Formula: see text]NH[Formula: see text]][M[Formula: see text](HCOO)[Formula: see text]][Formula: see text] and PDLLA/[CH[Formula: see text]NH[Formula: see text]][M[Formula: see text](HCOO)[Formula: see text]][Formula: see text], in which the formic acid MOFs are with different structures and different metal ions as fillers, including [NH 3 (CH[Formula: see text]NH 3 ][M II (HCOO) 3 ] 2 (namely MOF–Co (M [Formula: see text] Co), MOF–Mg(M [Formula: see text] Mg), MOF–Mn (M [Formula: see text] Mn), with 1, 4-butanediamine ion as guest) and [CH 3 NH 3 ][M[Formula: see text](HCOO) 3 ] 2 (namely MOF–Co[Formula: see text] (M = Co), MOF–Ni[Formula: see text] (Ni), with methylamine ion as guest). The composition and morphology of composite films were characterized by XRD, IR, SEM, DSC and UV, respectively, while the dielectric characterizations of the composites including the dielectric permittivity, the dielectric loss, the breakdown field strength and the energy density were also performed. The composition–structure–property relationships were also investigated including the influence of MOF content and MOF category. With the introduction of MOFs, the dielectric constant of the polylactic acid substrate was improved slightly while the breakdown field strength can be improved in some systems. Interestingly, the Co(II)-containing formic acid MOF has advantages over other formic acid MOFs with similar structure for the enhancement of the dielectric constant and breakdown field strength. Also, in some composite films with methylamine ion guest MOF fillers and low-MOF content (MOF–Co[Formula: see text] (1 vol.%) and MOF–Ni[Formula: see text] (1 vol.%)), the breakdown electric field enhanced significantly and further led to improved energy storage density which was about 43% higher than that of the polylactic acid matrix. The possible reason is that in these composites, the orientation of C–H bonds of MOFs seems more beneficial to the formation of hydrogen bonds between the carboxyl group of formic acid and the polylactic acid matrix. These relationships obtained from formic acid MOFs/polylactic acid composites are valuable to the design of high-performance polymer/MOF energy storage composites and may be a new perspective to the practical use of ferroelectric MOFs.

In this work, a sensor based on a modified porous aromatic framework (PAF-1-S) was successfully fabricated for humidity detection. The prepared sensor possesses promising sensing performance with balance response/recovery speed (both 18 s), narrow humidity hysteresis (similar to 4%RH), good sensitivity (617 k Omega/%RH), and stability in 11%RH-95%RH. The sensing mechanism was investigated by impedance spectrum (IS), equivalent electrical circuit, and density functional theory, indicating that the structure of PAF-1-S significantly improves the affinity of water molecules. These results show that PAF-1-S has the promising potential for humidity detection and provide a new design strategy for high-performance sensors.

Humidity sensors are of great significance in industry, agriculture and human activities, and many nanomaterials are already used for humidity sensing. Linear ionic polymers with hydrophilic groups have exhibited good humidity detection performance because they can adsorb water and then dissociate charged carriers. However, it suffers from the instability under high relative humidity that caused by polymer chain swelling and disengagement. To overcome this shortage, in this work, a new sensor based on hypercross-linked porous organic polymer (POP) with sulfonic acid group was fabricated to humidity detection in wide humidity range. The POP with strong covalent bonds exhibits remarkable chemical and thermal stability, and sulfonic acid group in the pore can act as fully accessible active site to enhance its ability to adsorb water. The obtained sensor shows high response (similar to 77) in a wide relative humidity range (11%-95% RH), short response/recovery time (9 s/21 s) and good stability. Complex impedance curves and density functional theory have been carefully investigated to understand its sensing mechanism. This work provides a new direction for the development of the impedancetype humidity sensitive materials in subsequent research and practical applications.

Solvent vapor-driven soft actuators are promising devices for human-environment interaction and have gained considerable attention in recent years. To enhance the interaction with the solvents and deliver a fast response and superior sensitivity, polymer/MOF composites are promising candidates for the fabrication of solvent-driven actuators. This paper presents a multiple-solvent-driven intelligent MOF-polymer soft actuator, namely MIL-88B/PVDF asymmetric film, and compares it to analogs based on other MIL-88(Fe) series flexible MOFs. This comparison investigates the deformation-structure relationship and the solvent-driven mechanism. The deformation of the MIL-88(Fe)/PVDF composite films in response to various organic solvents has been studied, and the structure and composition of the MOF fillers and the composites were characterized by SEM, FT-IR, and XRD. Furthermore, the MIL-88B/PVDF composite, which shows ability to respond to multiple solvents and a fast deformation response to several organic solvents through the solvent swelling/adsorption of the MOF skeleton and the appropriate flexibility and group affinity from the terephthalic acid ligand, was used to fabricate an inverted opal gradient actuator composed of MIL-88B, carbon black (CB) and PVDF, namely MIL-88B/CB/PVDF. The MIL-88B/CB/PVDF film not only realizes excellent dual-responsive deformation and discoloration to methanol vapor with fast visible deformation within 1 s with a maximum crimp angle of up to 558 degrees (10 vol% concentration) and a wide color change range covering six viewing-angle-dependent high-saturation colors (red, orange, yellow, green, blue and purple) but also shows an approximate linear relationship between the maximum curl angle and the solvent concentration for three solvents (methanol, toluene and chloroform). In addition, several smart devices have also been fabricated, including methanol-driven bionic petals, a worm robot, an alertor and a LIG sensor. Therefore, such polymer/MOF soft actuators have great potential in bio-robots and this work provides a new design strategy for smart materials. A multiple-solvent-driven soft actuator based on MIL-88B(Fe)/PVDF asymmetric film exhibits deformation response to methanol, toluene and chloroform.

A novel humidity sensor based on ionic porous polymer (IPP) microspheres was prepared in this work. The chemical structure and morphology of IPP microspheres were carefully characterized. The intrinsic hydrophilic ionic units of IPP, -N+R- and Br-, could enhance the adsorption of water molecules and ionic conductivity. The aromatic groups in IPP can adjust its hydrophobicity and ensure stability. Meanwhile, the structure of microspheres provides a favorable space of channels for water molecules transport, which improves the response speed of sensing film further. The impedance of the sensor based on IPP microspheres changed more than three orders of magnitude in the relative humidity (RH) range of 11-95 % RH with a good linearity (R-2=0.996) and a fast response speed (6 s/ 27 s). Finally, the mechanism was systematically studied by complex impedance spectrum and theoretical calculation. This study shows a new type of sensor based on ionic porous polymer microspheres, which will pave the way for IPP applications in humidity sensing.

Two water-soluble block copolymers composed of acrylic acid (AA), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), and optionally maleic anhydride (MAH) were synthesized through ammonium persulfate-catalyzed free radical polymerization in water. The introduction of aluminum sulfate (AS) into the resulting mixtures significantly reduced the setting times of the paste and enhanced the mechanical strength of the mortar compared to both the additive-free control and experiments facilitated solely by pure AS. This improvement was primarily attributed to the inhibition of rapid Al3+ hydrolysis, which was achieved through coordination of the synthesized block copolymers, along with the formation of newly identified hydrolytic intermediates. Notably, the ternary copolymer (AA–AMPS–MAH) exhibited superior performance compared to that of the binary copolymer (AA–AMPS). In the early stages of cement setting, clusters of ettringite (AFt) were found to be immobilized over newly detected linkage phases, including unusual calcium silicate hydrate and epistilbite. In contrast to the well-documented role of polymers in retarding cement hydration, this study presents a novel approach by providing both accelerating and hardening agents for cement setting, which has significant implications for the future design of cement additives.

Two-dimensional (2D) metal-organic framework (MOF) nanosheets have recently received extensive attention due to their ultra-thin thickness, large specific surface area, chemical and functional designability. In this study, an unconventional method using surface acoustic wave (SAW) technology is proposed to exfoliate large quantities and uniform layers of 2D MOF-Zn2(bim)4 nanosheets in a microfluidic system. We successfully demonstrated that the thickness of 2D MOF is effectively and accurately controlled by optimizing the SAW parameters. The mechanisms for the efficient exfoliation of 2D MOF nanosheets is attributed to both the electric and acoustic fields generated by the SAWs in the liquid. The electric field ionizes the methanol to produce H+ ions, which intercalate Zn2(bim)4 sheets and weaken the interlayer bonding, and the strong shear force generated by SAWs separates the MOF sheets. A yield of 66% for monolayer MOFs with a maximum size of 3.5 mu m is achieved under the combined effect of electric and acoustic fields. This fast, low-energy exfoliation platform has the potential to provide a simple and scalable microfluidic exfoliation method for production of large-area and quantities of 2D MOFs.