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Fixing the greenhouse gas CO2 through epoxide helps to mitigate worldwide ecological troubles. The applications of metal‐free and solvent‐free catalysts remain a challenge for CO2 catalytic conversion. In this work, an array of quaternary ammonium salts derived from polyethyleneimine with hydroxyl groups ([PEI‐GDMAB‐Cn]Br) were constructed by the reaction of branched PEI with a molecular weight of 10000 and glycidyl alkyl dimethylammonium bromide. A range of experiments were designed to demonstrate that [PEI‐GDMAB‐Cn]Br can be considered as a valid metal‐free and solvent‐free homogeneous catalyst for the CO2‐epoxide cycloaddition reaction. Among of [PEI‐GDMAB‐Cn]Br, [PEI‐GDMAB‐C18]Br catalyzed the model reaction of CO2 and epichlorohydrin under optimized reaction conditions (T=80 °C, 1.0 atm CO2, catalyst 1 mol%, ECH 15 mmol, 16 h) and the conversion achieved at 97.5 %. Moreover, the catalyst exhibited stable reusability and broad substrate applicability, which was used in the following cycle succinctly, because of self‐separated properties by temperature control. The [PEI‐GDMAB‐C18]Br catalyzed reaction process was detected as a pseudo‐first‐order reaction after kinetic studies and an Ea was calculated to be 50.65 kJ/mol. A combinatorial catalytic mechanism of hydrogen bonding and bromide ions is suggested to explain the remarkable catalytic performance of this bifunctional catalyst. [ABSTRACT FROM AUTHOR]

The properties of zein nanoparticles formed by anti-solvent precipitation are affected by solvent type, solvent composition, mixing method, and dilution ratio. Ultrasound is a non-thermal technology and can be used to assist in the fabrication of zein nanoparticles. Curcumin is a natural bioactive compound that has health benefits for humans. The objectives of this study were 1) to evaluate the effect of ethanol concentration, the ratio of the dispersed phase to continuous phase, and the amplitude of ultrasound on the properties of zein nanoparticles and 2) to assess the encapsulation and stability of curcumin in the zein nanoparticles via ultrasonic treatment. Zein nanoparticles were fabricated by ultrasonic treatment with various initial ethanol concentrations in the continuous phase, volume ratios of the dispersed to continuous phases, and ultrasound amplitudes. The particle size decreased as the concentration of ethanol in the continuous phase decreased. Curcumin was encapsulated by selected ultrasonic treatments and the particle size, encapsulation efficiency, and XRD of zein-curcumin nanoparticles were analyzed. The findings from this study provide insights and means for manipulating zein nanoparticles by adjusting processing conditions when using ultrasound. Also, encapsulation of bioactive compounds such as curcumin can be improved using controlled ultrasound treatment. • Zein nanoparticles were fabricated by ultrasonic treatment with various ratios of dispersed phase to continuous phase. • Zein-curcumin nanoparticles were fabricated by ultrasonic treatment with different initial ethanol concentrations. • The particle size increased as the ethanol concentration in the continuous phase increased. • The encapsulated curcumin was more stable toward heat and light than free curcumin. • At critical ethanol concentration, the nanoparticle formation and curcumin encapsulation changed significantly. [ABSTRACT FROM AUTHOR]

• Co-Salen complexes containing different groups and bearing potassium iodide (KI) complexed with crown ether (K@SCs) were prepared. • Salen derivative organic polymer as heterogeneous catalyst for CO 2 cycloaddition reaction. • Alkali metal halides and Lewis acids have good synergistic effects in catalytic reactions. Metallosalen presents very important applications in both homogenous and heterogeneous catalysis. Correspondingly, porous polymeric metallosalen combined with the performance of organometallics and heterogeneous polymers possess potential in CO 2 fixation reactions. Herein, a family collection of K@SCs were conceived and obtained by combining cobalt-salen complexes with different groups and diaminobenzene-18-crown-6 complexed with KI, which allows multiphase catalytic immobilization of CO 2 to epoxides. Catalyst K@SC-3 can fix CO 2 into a variety of substituted epoxides in >90% yields to the corresponding cyclic carbonates in co-catalyst-free and solvent-free conditions. Furthermore, K@SC-3 can be recovered and reused at least six times by simple centrifugal separation, demonstrating superior stability. The kinetics experiments were also carried out at varied temperatures catalyzed by K@SC-3. It is concluded that a first-order equation of epoxide was proved and the activation energy was calculated to be 27.13 KJ/mol. [Display omitted] [ABSTRACT FROM AUTHOR]

When konjac glucomannan (KGM) molecules are deacetylated under alkaline conditions, the aqueous KGM solution is transformed into a thermally stable gel. In this study, series of Na 2 CO 3 -induced and K 2 CO 3 -induced KGM hydrogels were prepared by deacetylation using different concentrations (0.1, 0.2, 0.3, and 0.4 M) of alkali. The hydrogels were characterized using texture profile analysis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy, X-ray diffraction, and rheological property analysis. The data showed that KGM hydrogel formation was facilitated at all the alkali concentrations used. The mechanisms of Na 2 CO 3 -induced and K 2 CO 3 –induced KGM hydrogels formation differed slightly. The hardness, springiness, chewiness, gumminess, and storage modulus G ′ of the Na 2 CO 3 -induced KGM hydrogels initially increased and then decreased with increasing alkali concentration. However, the values of the corresponding properties of the K 2 CO 3 -induced KGM hydrogels increased with increasing alkali concentration. All the data were consistent with the structures observed using SEM. The 0.3 M Na 2 CO 3 -induced KGM hydrogel had the highest hardness and storage modulus G ′, a well-proportioned network structure, and a dense architecture; 0.3 M Na 2 CO 3 was therefore the most suitable modifier for inducing KGM hydrogel formation. [ABSTRACT FROM AUTHOR]

• Additives affect recrystallization from the melt of commercial linear low density polyethylenes (LLDPE). • Additives are consumed after melt-reprocessing and the effect of melt-memory or self-nucleation on recrystallization can be followed by DSC. • The effect of melt-memory on recrystallization of LDPEs and metallocene LLDPEs differs from the behavior of broadly distributed Ziegler-Natta LLDPEs. • Studying the effect of melt-memory on recrystallization of LLDPEs by DSC is a simple avenue to identify if LLDPEs undergo liquid-liquid phase separation (LLPS) on cooling from the melt. Compared with a constant recrystallization rate of commercial linear low density polyethylenes (LLDPE) as a function of melt temperature, copolymers reprocessed in an open twin-screw extruder, display the expected strong melt-memory features upon melting followed by recrystallization. Precipitation from dilute solution had the same effect on melting-recrystallization of commercial copolymers. In the twin-screw melt re-processing, a small content of long-chain branches and crosslinks are incorporated to the copolymer's structure, but especially a further consumption of additives uncovers self-nucleation features that speed up recrystallization and are related to the major copolymer microstructure. The observed difference in re-crystallization behavior between metallocene type and Ziegler-Natta (ZN) type copolymers, both with equivalent average comonomer content and molecular mass, is due to the inter-chain comonomer distribution. While for metallocene-made and low density polyethylenes, below a critical melt temperature the recrystallization rate increases continuously with decreasing melt temperature, in broadly distributed ZN copolymers there is an inversion of the temperature gradient of the rate at the onset of liquid-liquid phase separation (LLPS). The mass fraction of highly branched molecules required to observe the onset of LLPS via melting followed by recrystallization was evaluated from the TREF profiles, and the effect of self-nucleated melts at different levels on the overall spherulitic morphology was observed via polarized optical microscopy. [Display omitted] [ABSTRACT FROM AUTHOR]

The orientation of the dispersed phase and crystals in the injection-molded bar of an impact polypropylene copolymer (IPC) containing isotactic polypropylene (iPP), ethylene-propylene rubber (EPR) and a β-nucleating agent (β-NA) were studied simultaneously. In the IPC, iPP and EPR act as the matrix and dispersed phase, respectively. The EPR is amorphous and the iPP is crystallizable in α- and β-crystalline forms in the presence of the β-NA. The orientation and orientation distribution for both of the EPR phase and the iPP crystals, as well as the crystallization behavior of iPP, were investigated by two-dimensional wide-angle X-ray diffraction (2D-WAXD), two-dimensional small-angle X-ray scattering (2D-SAXS), scanning electron microscope (SEM) and differential scanning calorimetry (DSC). The results of the experiment show that orientation exists for both the EPR phase and the iPP crystals. But their orientation distribution manifests an opposite tendency. The EPR phase was observed to be highly oriented in the core layer but the orientation of the iPP crystals was weakened gradually from skin to core. The difference in the orientation behavior between the EPR phase and the iPP crystals reflects the distinct response of the micrometer-scale EPR particles and nanometer-scale iPP chains upon the flow field and temperature gradient in the mold. The diffraction geometry of the β-crystals has also been discussed in detail. The observations in this study may shed light on the study in the structure and property relationship for the IPC injection-molded products. • The orientation of the rubber phase and polypropylene crystals were studied simultaneously in an impact propylene copolymer (IPC). • Morphology, calorimetry, and X-ray methods were applied. • The rubber particles and polypropylene crystals were oriented differently. • The orientation of the polypropylene in the presence of the β-nucleating agent was analyzed. • The findings are important for the research and application of IPC. [ABSTRACT FROM AUTHOR]

This paper proposes a new framework of defining an overall constitutive model of the fibrous composite material with separated constitutive models of the fiber and the matrix phases. The framework stems from the first-order reduced-order-homogenization (ROH) method. The ROH method requires a set of influence functions to describe the interaction between material phases, which can be computed by solving a number of finite element problems of the fibrous meso-structure with periodic boundary conditions. This paper proposes an analytical methodology to evaluate the influence tensors. In this way, the overall constitutive model of the fibrous composite material is constructed by analytical influence tensors and stand-alone material models of the fiber and matrix phases, which can represent comprehensive material degradation mechanism at meso-scale. Finally, an example of overall constitutive model is defined and tested, with both fiber and matrix phases are assumed as the isotropic continuum damage model. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SP-COPs exhibited high catalytic efficiency of CO 2 conversion and excellent I 2 adsorption capacity. • The synergistic mechanism of CO 2 conversion was proved by experimental and kinetics. • The iodine adsorption kinetic process was described. The fixing reactions of carbon dioxide with epoxides will not only help to ameliorate the problem of global warming, but also facilitate the synthesis of cyclic carbonates that have a multitude of applications. Herein, a new sequence of Salen cobalt complexes adjusted with different counterions and interconnected with pyrene group were synthesized through Friedel–Crafts alkylation, which were served as conjugated organic polymers (SP-COPs) for taking advantage of catalytic CO 2 fixation reactions and iodine adsorption. Further characterizations were carried out through FT-IR, UV, TGA, and SEM to comprehend the intact structure, thermal stability, morphology and other physical and chemical properties. All materials exhibited effective catalytic performance, and in particular, SP-COP-1 with co-catalyst of TBAI achieved 96.2% conversion under ultra-mild conditions. The E a was obtained to be 46.4 kJ·mol−1 by performing kinetic experiments at different temperatures by fitting the experimental data. The performance of iodine vapor adsorbed by these materials at ambient pressure of 75°C reached 2.8 g·g−1, 2.2 g·g−1 and 2.6 g·g−1 respectively, and the adsorption process is describable in terms of pseudo-first-order and pseudo-second-order adsorption kinetics. [ABSTRACT FROM AUTHOR]

• The Tröger base analogue coordinated with potassium iodide and containing crown ether CATB-KI was fabricated. • The acidified CATB-KIs shown high catalytic efficiency to cyclic carbonates. • The synergistic mechanism has been proved in terms of experimental results and calculation of dynamics. Tröger's bases (TB) containing two steric nitrogen atoms, are alternated as building block for constructing molecular acceptors to form covalent bonds with acids, making TB a promising catalyst. Herein, TB analogs fabricated with crown ethers were knitted by condensation reaction and combined with potassium iodide as a brand-new catalytic system (CATB-KIs), which were characterized using FT-IR, 13C CP MAS NMR, SEM, TGA, and XPS spectroscopy respectively. The generated CATB-KIs exhibited excellent performance for CO 2 fixation reaction with epoxides to produce cyclic carbonates under mild conditions, and the catalytic activity could be further improved by coordinating with acids beforehand, in which HBr performs fascinated activity. After 12 h, the corresponding cyclic carbonate from epichlorohydrin with 95.1% yield was detected at mild conditions with solvent-free in the presence of CATB-KI-2 and HBr. A series of terminal epoxides were converted into desired cyclic carbonates with desirable yields. The catalyst could be recovered successfully and reused six times without significant loss of activity. Finally, dynamics study on catalytic mechanism has been accomplished and the activated energy was calculated as 72.1 kJ/mol. A synergistic catalytic mechanism of hydrogen bonding and I anion has been proposed to account for the excellent catalytic activity of this catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

In recent years, rubber toughened polypropylene (PP) blends have been extensively investigated with special regard to the importance of PP matrix properties (e.g., crystal morphology and structure) in tailoring the toughening efficiency. Unfortunately, although high melt flowability is indispensable to the processing of polymers into complex thin-wall products, it remains a huge challenge to achieve a marvelous balance between stiffness and toughness in the blends with relatively low matrix molecular weight. Herein, taking PP/EPR (ethylene-propylene copolymer) blends as an example, the combined effects of matrix molecular weight and crystallinity on the mechanical properties of PP/EPR blends have been examined in both experiment and theory. The experimental results show that decreasing molecular weight leads to significant deterioration in notched impact toughness, tensile strength and Young's modulus. Impressively, the toughness loss caused by the decrease of molecular weight can be well-compensated by a slight reduction in the matrix crystallinity, without evidently sacrificing the strength and modulus, demonstrating an improved stiffness-toughness balance. Theoretical analysis indicates that the impact toughness of PP/EPR blends is heavily dependent on the chain entanglement density (v e) of PP matrix, and a linear relationship between critical interparticle distance (ID c) and the v e 1/3 has been verified from both experiment and theory. Moreover, it is interesting to find that decreasing matrix crystallinity can increase the v e of low-molecular-weight PP matrix, which enables the effective toughening at lower concentration of EPR and thus gives rise to less loss in the strength and modulus. We believe this work not only gives a new insight into the role of chain entanglement in the toughening but also provides a promising guidance for the design of high-performance PP with high melt flowability. [Display omitted] • Combined effects of M n and crystallinity on the toughening efficiency of PP/EPR blends were studded. • The relationship between the ID c and v e of PP matrix i.e. ID c ∼ v e 1/3 , was given for the first time. • Matrix with higher M n or lower crystallinity has higher v e , exhibiting larger ID c. • Toughness loss caused by decreasing M n can be compensated by reducing crystallinity. • Low-viscosity PP/EPR blends with good toughness-stiffness balance were obtained. [ABSTRACT FROM AUTHOR]