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Herein, we reported a new bergenin: 4-aminobenzamide (BGN-4AM) cocrystal with significantly enhanced solubility and low hygroscopicity probed from two aspects such as phase solubility ...diagrams and theoretical calculations. Compared with anhydrous BGN, BGN-4AM solubilities in water and different buffer solutions (pH = 1.2, 4.5, 6.8) increase significantly. It is noted that BGN-4AM solubility in pH = 6.8 buffer solution presents 32.7 times higher than anhydrous BGN. Interestingly, BGN-4AM (0.31 ± 0.07%) showcases lower hygroscopicity than anhydrous BGN (9.31 ± 0.16%). The predicted and experimental solubilities agree with each other when considering solubility product (Ksp) and solution binding constant (K11) in phase solubility diagrams, indicating the solution complexes formation occurs. Further crystal surface-water interactions and Bravais, Friedel, Donnay-Harker (BFDH) analyses based on Density Functional Theory with dispersion correction (DFT-d) methods support the enhanced solubility. The water probe demonstrates an average interaction energy of −6.48 kcal/mol on the 002 plane of BGN-4AM, and only −5.47 kcal/mol on the 011 plane of BGN monohydrate. The lower lattice energy of BGN-4AM guarantees its lower hygroscopicity than BGN monohydrate. BGN-4AM with enhanced solubility and low hygroscopicity can be a potential candidate for further formulation development.
Uncertainties in estimating the hygroscopicity of bulk aerosols under conditions of low relative humidity (RH) or below the deliquescent RH (DRH) of aerosols remain to be significant, mainly due to ...the presence of water-soluble organic matter (WSOM). To quantify the contributions of WSOM to aerosol hygroscopicity and associated uncertainties, a field campaign was conducted to measure the hygroscopic growth curve (f(RH)) of bulk aerosols online, dominant chemical compositions in PM2.5 online and offline, and size distributions of the dominant chemical compositions offline during the dry and wet seasons of 2019–2020 in urban Guangzhou of south China. Based on the measured f(RH), the hygroscopicity parameter (κ) of bulk aerosols (κ-f(RH)) exhibits a logarithmic increase with increasing RH until RH reaches 69 %. Beyond this threshold, κ-f(RH) increases very slowly with further increase of RH, reaching 0.32 ± 0.04 during the dry season and 0.31 ± 0.05 during the wet season. The κ of WSOM (κ-WSOM) was further estimated to be 0.22 ± 0.03 and 0.13 ± 0.04 in the dry and wet seasons, respectively, when RH > 69 %. WSOM significantly affects κ-f(RH) by retarding the deliquescence process of aerosols and altering the mass ratio of water-soluble inorganic salts (WSIS) to WSOM within the size range of 0.4–0.9 μm, especially under low RH conditions (<60 %). The κ-f(RH) under low RH conditions was revised based on the logarithmic regression equation between RH and the ratio of measured κ-f(RH) to estimated κ-f(RH>69%). f(RH) of WSIS and WSOM were then corrected using the revised κ-f(RH) under low RH conditions, which showed 22–31 % lower values than those produced by the IMPROVE formulas.
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•The hygroscopicity parameter of WSOM was estimated for dry and wet seasons.•κ-f(RH) increased with increasing RH before deliquescence of particles.•f(RH) was underestimated under low RH conditions due to the presence of WSOM.•A revised f(RH) for hygroscopic chemical species was developed.
Thin (ca. 340 nm) chitosan coatings were deposited onto glass substrates via dip-coating, then modified with the methanol solution of decanoic anhydride (0.17–56 mM). NMR, FTIR and XPS measurements ...confirmed that the acylation degree increased from 18 % to 45 %, and at the highest degree, the whole layer was acylated homogeneously by the reagent molecules. The coating thickness increased (up to 60 %), and the refractive index decreased (from 1.541 to 1.532) due to the acylation, that was determined by UV–visible spectroscopy. The AFM did not reveal morphological changes, but wetting tests showed that the acylation rendered the coating hydrophobic (water contact angle increased from ca. 75° to 100°). The contact angle, however, decreased to 85° due to the development of a second molecular layer of the decanoic acid by-product at the highest (over 25 mM) reagent concentrations. XRD studies showed a self-assembling structuring of the alkyl-chains in the bulk phase, which occurred in the case of the highest degree of acylation. This also manifested itself in a significant decrease of the layer hygroscopicity: the swelling degree decreased from 40 % to 8 % in a saturated water atmosphere monitored by spectroscopic ellipsometry.
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•ADN-based composite microspheres show high sphericity and narrow particle size.•The hygroscopicity of ADN-based composite microspheres was significantly reduced.•ADN-based composite microspheres ...show a greatly improved safety performance.•The ADN/fluorine rubber(F2602) sample possesses a lotus leaf-like hydrophobic effect.•Is expected to help realize the application of ADN in composite solid propellants.
Ammonium dinitramide (ADN) is an ideal solid composite propellant oxidizer. But it also exhibits high hygroscopicity and low safety. Solving these issues will be crucial of ADN in practical applications. In this study, three ADN-based energetic composite microspheres were prepared by suspension assembly process coating ADN with different polymeric materials (glycidyl azide polymer (GAP), fluorine rubber(F2602), and hydroxyl-terminated block copolyether(HTPE)). The experimental results showed that the three prepared samples were spherical particles with regular morphology and uniform particle size. The crystal structure was not changed. The contact angle, moisture absorption and mechanical sensitivity test showed that the ADN-based energetic composite microspheres have low moisture absorption and mechanical sensitivity. In particular, the ADN/F2602 sample, which possesses a lotus-like hydrophobic effect, exhibits a 57.24 % reduction in water absorption compared to the raw ADN, and the contact angle of ADN/F2602 (93.91°) is 4.24 times higher than that of the raw ADN (22.15°). The critical friction susceptibility of ADN/F2602 (168 N) is 2.1 times higher than that of raw ADN (80 N), and the critical impact susceptibility of ADN/F2602 (17 J) is 2.43 times higher than that of raw ADN (7 J). The combustion test showed that the combustion duration of ADN/F2602 increased from 1.353 s to 1.578 s for the raw ADN, and the flame intensity was enhanced. The successful ignition and flame stabilization of ADN/F2602 samples after 24 h storage under a relative humidity of 60 % indicates its good energy release performance in a propellant. Through this study, F2602 as a capping material has good anti-hygroscopic effect, mechanical insensitivity and combustion stability for ADN, which can support the application of ADN as an oxidizer in composite solid propellants.
Ammonium nitrate (AN) is widely used in agriculture, explosives and propellants, but its strong hygroscopicity limits its further application. In this paper, a novel water vapor modeling method is ...proposed to evaluate the hygroscopicity of AN particle under various temperature and relative humidity (RH) environments. Molecular dynamics simulations are employed to investigate the intermolecular interactions during the moisture absorption process. The simulation results demonstrate that the hygroscopicity of AN exhibits an increasing trend with both temperature and RH, and electrostatic force is the main reason for hygroscopicity. Moreover, the influence of temperature on hygroscopicity is found to be more significant compared to RH. Combining experiments and simulations, a mathematical formula has been developed for rapidly comparing the hygroscopicity of AN in specific environments. This method demonstrates simplicity, efficiency, and accuracy, enabling assessment of the hygroscopic performance of AN (or modified AN) across a broad spectrum of temperature and RH conditions.
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•A new method to simulate hygroscopicity at various temperatures and humidities.•The intermolecular interactions between AN and water were studied.•The variation rule of H-bond strength during hygroscopy was obtained.•The relative hygroscopicity pattern of AN in various environments was predicted.
The conditions of the storage environment, mainly related to temperature and relative humidity, influence the interaction of seeds with the environment and, consequently, the water content of the ...product. The study aimed to analyze the influence of ambient temperature and relative humidity on the water content of Annona squamosa seeds. The experiment was carried out in a completely randomized design with a 5x7 factorial scheme, with five temperatures (15, 20 and 25, 35, 40ºC) and seven conditions of relative humidity with nine replications. The equilibrium moisture content of the seeds was analyzed by mass difference. Data were subjected to analysis of variance by the F test and regression analysis. For significant interaction between the sources of variation, multivariate analysis was performed. Through regression analysis, linear models were obtained for the analyzed temperatures. Through multivariate analysis, a mathematical model was obtained to predict the equilibrium humidity of the pinecone considering temperature and relative humidity. The moisture in A. squamosa seeds is influenced by the temperature and relative humidity of the environment. Obtaining a mathematical model by multivariate analysis allows an adequate prediction of equilibrium moisture.
Poly(isosorbide carbonate) (PIC) is an example of the shift from fossil to bio‐based feedstocks in polymeric materials. However, the naturally high hygroscopicity of isosorbide may lead to the bad ...dimensional stability of its polymers, limiting its application. This work aims to develop a series of isosorbide‐based copolycarbonates by introducing hydrophobic groups, such as alkane chains and aromatic rings, into the polymer backbone via one‐pot melt polycondensation. As expected, the molecular structure and steric hindrance of the comonomer have a remarkable effect on the water absorption of the copolycarbonates. Among the comonomers, tricyclo5.2.1.0(2,6)decanedimethanol with an alkane skeleton bridge effectively reduces the saturation water absorption by 61% compared to PIC. The water absorption mechanism and kinetics of the copolycarbonates are investigated. Moreover, the incorporation of comonomers in PIC not only exhibits stronger hydrophobicity, but also significantly improves its optical properties. Copolycarbonates obtained have a light transmittance of 92% and a refractive index of 1.5394, which are higher than those of PIC, along with better thermal stability, flexibility, and lower glass transition temperature. This work provides a new strategy for the design of isosorbide‐based polycarbonates for use in optics.
In this paper, a series of novel poly(diol‐co‐isosorbide) carbonates (PDICs) have been designed and developed through the melt polymerization of ISB and seven hydrophobic comonomers catalyzed with the ionic liquid catalyst 1‐ethyl‐3‐methylimidazole lysine (EmimLys). The poly (tricyclo5.2.1.0(2,6)decanedimethanol‐co‐isosorbide carbonate) (PTIC) effectively reduced the saturation water absorption by 61% compared to poly(isosorbide carbonate) and exhibited excellent optical properties, thermal and mechanical properties.
Visibility is a simple indicator of air quality, and its drastic decrease is often related to poor air quality resulting from an increase in aerosol (particulate matter PM) concentration. Visibility ...is also related to water vapor due to the hygroscopicity of aerosols. As a result, water vapor may considerably influence PM measurements especially in the case of low-cost PM sensors which typically measure the ambient (wet) size of PM. Several possibilities are available to eliminate the effect of aerosol hygroscopicity on PM10 measurements, and we aimed to discuss and compare three of the methods: gravimetry (mass change of aerosol filters due to RH variation), application of the AIM model (based on aerosol chemical composition) and estimation derived from visibility data. In this work, we discuss how hygroscopic growth factors, obtained from different methods, are related, as well as the relevance of the hygroscopic growth rate derived from visibility observations in PM10 measurements. Moreover, since in PM monitoring – including the low-cost PM sensors – a quasi-real time, appropriate and simple method would be desirable for consideration of aerosol hygroscopicity, we aimed to construct a proxy for this purpose. We found that the visibility-derived mass growth rate could serve as a simple basis for these requirements.
•The hygroscopic growth factors obtained from different methods are compared.•The growth rates depend on chemical composition and the relative humidity history.•The relevance of visibility-derived hygroscopic growth rate in PM10 is studied.•A proxy from visibility-derived mass growth rate is constructed.•The proxy is in good correlation with the measurements.
Two intermolecular energetic materials are successfully designed and prepared by the self-assembly of 5-aminotetrazole and transition metal ions on the surface of ammonium perchlorate particles, ...which exhibit considerable application prospects in improving the combustion and energy performance and reducing the hygroscopicity of solid rocket propellants.
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•AP/Cu(5-ATZ)4Cl2 and AP/Co(5-ATZ)4Cl2 IEMs were successfully designed and prepared.•The prepared AP/Cu(5-ATZ)4Cl2 and AP/Co(5-ATZ)4Cl2 IEMs have high heat release.•M(5-ATZ)4Cl2 (M = Cu, Co) has high catalytic activity on thermal decomposition of AP.•The prepared IEMs can significantly improve the burning rate of propellant.•The prepared IEMs can resist moisture absorption and agglomeration.
Intermolecular energetic materials (IEMs) have become the focus of attention due to their excellent performance in combustion, ignition, energy release and sensitivity. In this paper, two IEMs were successfully designed and prepared by the self-assembly of 5-aminotetrazole (5-ATZ) and transition metal ions on the surface of ammonium perchlorate (AP) particles. The scanning electron microscope, infrared spectroscopy, powder X-ray diffraction, thermogravimetric analyses, and differential thermal analyses were employed to characterize the prepared samples. The results show that the surface of AP particles is completely covered by a uniform and dense M(5-ATZ)4Cl2 (M = Cu, Co) self-assembled layer. Thermal analyses show that the high-temperature decomposition peak temperatures of AP/Cu(5-ATZ)4Cl2 (10 wt%) and AP/Co(5-ATZ)4Cl2 (10 wt%) are decreased by 93.3 °C and 127.1 °C compared to the case of pure AP, while the heat releases of them are increased by 539 J∙g−1 and 580 J∙g−1. In addition, the burning rates of AP/Cu(5-ATZ)4Cl2/Al (10 wt%) and AP/Co(5-ATZ)4Cl2/Al (10 wt%) are increased by 6.8 mm∙s−1 and 7.8 mm∙s−1 compared with the case of AP/Al. Moreover, the hygroscopicity tests show that the prepared samples do not agglomerate aftter being placed in the atmosphere with a relative humidity of 79% for 66 h. This research shows considerable application prospects in improving the combustion and energy performance of solid propellants, it is also a reference for the design and preparation of other novel IEMs.
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