Poly Content Research Articles

In-situ one-step construction of poly(heptazine imide)/poly(triazine imide) heterojunctions for photocatalytic hydrogen evolution.

The construction of heterojunctions is challenging, requiring atomic-level contact and interface matching. Here, we have achieved atomic-level interfacial matching by constructing poly(heptazine imide)/poly(triazine imide) crystalline carbon nitride heterojunctions in an in-situ one-step method. The content of poly(triazine imide) in heterojunctions is positively related to the proportion of lithium chloride in potassium chloride and lithium chloride mixed-salts. The optimized heterojunction achieves an apparent quantum efficiency of 48.34 % for photocatalytic hydrogen production at 420 nm, which is at a good level in polymeric carbon nitride photocatalysts. The proposed ion-thermal assisted heterojunction construction strategy contributes to the development of polymeric carbon nitride photocatalysts with high crystallization and high charge separation efficiency.

Miscibility and crystallization behavior of Poly(butylene terephthalate)/Poly(ethylene terephthalate-co-1,4-cyclohexylene dimethylene terephthalate) blends

The miscibility and crystallization behavior of a series of polymer blends containing different content of poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate-co-1,4-cyclohexylene dimethylene terephthalate) (P(ET/CT)) have been studied. It is confirmed through DSC, SAXS and SEM that PBT is miscible with P(ET/CT) with different CT content. When the mole content of CT is 37 %, P(ET/CT) (abbreviated as P(ET/CT37 %)) is fully amorphous. But, as the mole ratio of CT is 66 %, P(ET/CT) (abbreviated as P(ET/CT66 %)) possesses crystallizability. Compared to the extremely fast crystallization of PBT, the crystallizability of P(ET/CT66 %) is so weak that non-isothermal crystallization (at a cooling rate of 10 °C/min) can hardly occur. Upon blending, however, it is interesting to find that the P(ET/CT66 %) could be involved in the crystallization of the blends within the entire composition range. In the DSC cooling curves, a double-peak crystallization could be observed, in which the Tc1 is attributed to the crystallization of PBT and the Tc2 to that of P(ET/CT66 %). Further, the two glass transition temperatures of the blends after crystallization confirm the occurrence of crystallization-induced phase separation at higher P(ET/CT) content. Therefore, the excluded P(ET/CT66 %) local domain or aggregation is regarded as the prerequisite of the P(ET/CT66 %) crystallization, and the previously formed PBT crystals act as its nucleating agent.

Removal of cadmium in contaminated soils by self-sustaining smoldering

Soil contamination by Cd presents a significant challenge for global eco-environment, while pyrolysis is an effectively method to removal of Cd in the soil, the further application of the technology has obstacle by the high device cost, large energy consumption and soil degradation. This study explored the application of self-sustaining smoldering as an energy-efficient technique for remediating of Cd-contaminated soils. The results shown that Cd could be desirable evacuated from soil by manipulate the key experiment parameter, especially the Cd-contaminated soil-to-PNs ratio. In this process, the content of Poly(vinyl) chloride (PVC) significantly influences the efficiency of Cd removal. Only 18.53 % of Cd was removed without PVC compared to that of 74.30 % after 3 % PVC was added into the soils. Chlorination of Cd(II) is the main reason for the removal of Cd during smoldering with PVC, which contrast to the volatilization of Cd is governed by reduction without PVC. Importantly, smoldering could effectively decline Cd species in the acid-soluble fraction and lower the bioavailability of Cd in treated soils with the DPTA-Cd decreased by 4.90–17.23 times compared with the untreated soils. Furthermore, due to the formed solid products, smoldering operation significantly increased soil total phosphorus and available phosphorus in the remediated soils, which is benefit for the reclamation goals. Overall, this study shows a great potential for remediation of Cd-contaminated soils by self-sustaining smoldering in the remediation industry.

The influence of poly(maleic anhydride - co - vinyl acetate) on polylactide/wood flour/calcium carbonate composites

In this paper, polylactide (PLA)/wood flour (WF)/calcium carbonate (CC) composites with different content of poly(maleic anhydride -co- vinyl acetate) (PMAVA) were prepared. PMAVA was obtained by radical solution polymerization and identified by FTIR. The torque - time curves showed that the balance torques of PLA/WF/CC composites with PMAVA were improved by the adding of PMAVA. SEM photographs showed that after the addition of PMAVA, the compatibility and interfacial adhesion between the filler (CC or WF) and PLA in each composite were increased. DSC heating curves showed that two cold crystallization temperature (Tcc) peaks appeared in each PLA/WF/CC composite, and the Tcc peak at high temperature and Tm peak in the composite containing PMAVA were split into two peaks, showing that the effects of WF and CC on the crystal of PLA were uncorrelated, and the presence of PMAVA decreased the crystal integrity of PLA. The tensile test results showed that the tensile strength and modulus of the composite were increased with the addition of PMAVA, and the composite with 0.5 wt% of PMAVA owned the best tensile performance. The hydrolysis results showed that the use of low content of PMAVA in the composite was beneficial to improve its hydrolysis rate.

Foreign Language Teaching: Content of Poly- And Multicultural Education

The paper considers foreign language teaching through addressing the issues of quality in education and highlighting the significance of including certain methodologies connected with educating poly- and multicultural personalities in teacher training processes. The mentioned anticipates changes to be made not only to the structure of teaching foreign languages in polyand multicultural education but also to the educational content. Therefore, what is discussed first relates to a huge dilemma on the terrains of Ukraine, neighbouring and some post-Soviet countries in respect of wrong and/or misleading usage of the terms ‘polyculturalism’, ‘multiculturalism’, ‘polycultural education’, ‘multicultural education’, etc., as well as disconnection of major researches in the clear differentiation among poly- and multicultural education, intercultural and cross-cultural communication and so on. The paper scratches tentatively on the discrepancies identified in the foreign publications of Russian scholars, which might have been built up on verified research data but fail to meet the factual reality as per surveys and questionnaires conducted by independent trusted global agencies. The principal value of the work may associate with the objectives of poly- and multicultural education described in the main body, and a list of expected qualities of a future foreign language teacher who is poly- and multiculturally diverse and ready to face today’s challenges in a globalising world.

Foreign Language Teaching: Content of Poly- And Multicultural Education

Foreign Language Teaching: Content of Poly- And Multicultural Education

Amphiphilic chitosan-g-poly(trimethylene carbonate) – A new approach for biomaterials design

The paper presents the synthesis and characterization of poly(trimethylene carbonate) grafted chitosan as a new water soluble biopolymer suitable for in vivo applications. The synthesis was performed via ring-opening polymerization of 1,3-dioxan-2-one (trimethylene carbonate) (TMC) monomer, initiated by the functional groups of chitosan in the presence of toluene as solvent/swelling agent. By varying the molar ratio between the glucosamine units of chitosan and TMC, a series of chitosan derivatives with different content of poly(trimethylene carbonate) chains was synthetized. The structural characterization of the polymers was realized by FTIR and 1H NMR spectroscopy and their solubility was assessed in water and in organic solvents as well. The biocompatibility was investigated by MTS assay on Normal Human Dermal Fibroblasts, and the biodegradability was evaluated in lysozyme buffer solution. Further, the surface properties of the polymer films were analyzed by polarized optical microscopy, atomic force microscopy and water-to-air contact angle measurements. It was established that, by 5% substitution of chitosan with poly(trimethylene carbonate) chains having an average polymerization degree of 7, a water soluble polymer can be attained. Compared to the pristine chitosan, it has improved biocompatibility in solution and moderate wettability and higher biodegradability rate in solid state, pointing its suitability for in vivo applications.

Fabrication of Open‐Cell Microcellular Acrylonitrile Butadiene Styrene Composite Foams with Enhanced Electrical Conductivity and High‐Performance Electromagnetic Interference Shielding

Porous materials are becoming progressively more popular because of their potential applications in the fields of oil−water separation, drug delivery, gas adsorption, and chemical sensing. Herein, acrylonitrile butadiene styrene (ABS) porous materials by the etching method and supercritical CO2 (SC‐CO2) foaming after the etching method are proposed. On this basis, ABS porous conductive composites are prepared by adding conductive carbon black (CCB). The results show that as the content of poly (ethylene oxide) (PEO) in the blend increases to 50 phr, the ABS materials prepared by SC‐CO2 foaming after the etching method all become open‐cell structures. When the content of CCB reaches 6%, the conductivity of ABS porous materials prepared by the etching method is 2.56 Sm−1; after etching, the conductivity of ABS porous materials prepared by SC‐CO2 foaming can reach 15 Sm−1 and electromagnetic shielding can reach 23 dB. When the content of CCB is greater than 6%, the conductivity is significantly improved. The conductivity of the ABS open‐pore materials prepared by the two methods can reach 15 Sm−1, and the maximum electromagnetic shielding can reach 33 dB. The developed foam has a great potential in electronics and electromagnetic interference (EMI) shielding application.

Tailoring the properties of waterborne polyurethanes by incorporating different content of poly(dimethylsiloxane)

A series of novel waterborne polyurethanes (WBPUs) was synthesized using α,ω-dihydroxypropyl poly(dimethylsiloxane) (PDMS), isophorone diisocyanate (IPDI), 2,2-bis-(hydroxymethyl) propionic acid (DMPA) and triethylamine (TEA). Different DMPA/PDMS molar ratio (from 0.2 to 0.7) and fixed –NCO/–OH molar ratio of 1.7, has been applied for the synthesis of six different WBPU films, without utilization of chain extension step during the synthesis. The structure of the prepared WBPUs was examined and confirmed by FTIR and NMR spectroscopy. The particle size of the prepared WBPU dispersions and molecular weight of WBPU films decrease with increasing DMPA content. In order to investigate the effect of the DMPA/PDMS ratio on thermal, mechanical and morphological properties, as well as the water resistance of the prepared WBPUs, diverse experimental techniques, such as thermogravimetric analysis, dynamic mechanical analysis, tensile tests, X-ray diffraction analysis (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and water contact angle measurements have been carried out. This research has shown that the incorporation of PDMS in WBPUs led to the appearance of microphase separation and provided surface hydrophobicity, good thermal and mechanical properties, which allow application of these WBPUs as coatings for various purposes.

Zwitterionic semi-IPN electrolyte with high ionic conductivity and high modulus achieving flexible 2.4 V aqueous supercapacitors

Polymer electrolytes (PEs) have the widespread interest for solid-state supercapacitors. As an ideal PEs, it is requested to possess high ionic conductivity, high electrolyte content, and excellent mechanical properties. Here, we present the zwitterionic semi-interpenetrating polymeric network electrolytes (ZSIPNEs) that enable achieving ultra-high ionic conductivity and excellent mechanical properties. ZSIPNEs are synthesis by interpenetrating various content of poly(sulfobetaine methacrylate) (pSBMA) into zwitterionic polymer (ZP) matrix, being simply prepared by 17 m NaClO4(aq) intake. At content of pSBMA of 0.1%, ZS-0.1 possesses the ultra-high ionic conductivity of 135.2 mScm−1 at 25 °C. In addition, ZS-0.1 shows excellent mechanical properties, including the compressive strength of 0.36 MPa, compressive strain of 74.5%, compressive modulus of 33.7 kPa, and toughness of 4.329 Jm−3. Furthermore, the electrochemical performances of electrolytes are studied using carbon-based supercapacitors which are assembled with 17 m NaClO4(aq) (C-aq), ZS-0 (C-ZPE), and ZS-0.1 (C-ZSIPNE), being evaluated by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge. C-ZSIPNE shows the wide electrochemical window of 2.4 V and the superior electrochemical performance by delivering high energy density of 83.6Whkg−1, and high power density of 19.1kWkg−1. Under bending angles of 90°, the capacitance of C-ZSIPNE keeps at almost 100%, being potential application in flexible supercapacitors. 3 brief informative subheadingsZwitterionic polymer electrolyte, Semi-interpenetrating polymeric network, High performance supercapacitors BackgroundPolymer electrolytes (PEs) have the widespread interest for solid-state supercapacitors. As an ideal PEs, it is requested to possess high ionic conductivity, high electrolyte content, and excellent mechanical properties. MethodsThe ionic conductivity of PE was evaluated by electrochemical impedance spectroscopy. The mechanical properties of PE were evaluated by compressive strain-stress curve. The electrochemical properties of PE were evaluated by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge. Significant FindingsZSIPNEs enable achieving ultra-high ionic conductivity of 135.2 mScm−1 and excellent mechanical properties (compressive modulus of 33.7 kPa). C-ZSIPNE shows the wide electrochemical window of 2.4 V and the superior electrochemical performance by delivering high energy density of 83.6Whkg−1, and high power density of 19.1kWkg−1. Under bending angles of 90°, the capacitance of C-ZSIPNE keeps at almost 100%, being potential application in flexible supercapacitors.

Effect of Different Molecular Weight of PEG on the Crystallization Behaviors of Binary Polymer Blends PLA/TPS

Serial poly (lactic acid) (PLA) and thermoplastic starch (TPS) blends (with a fixed content of 20 wt.% TPS) were prepared by melt extrusion process. The effect of different molecular weight of PEG on the thermal and rheological properties of PLA/TPS blends was studied by the melt flow rate (MFR) and DSC analysis. The results showed that the molecular weight of PEG influenced the miscibility and crystallization behavior of PLA/TPS blends. Blend added with PEG400 showed a single Tg, and blends with PEG600 provided remarkable improvement of rheological properties with an increase in flow rate to 49.02 g/10 min. 4% content of poly (ethylene glycol) (PEG) can positively contribute to improve crystallization rate of PLA by reducing the melting temperature and cold crystallization temperature.

Effect of the molecular weight of poly(vinyl acetate) on the polymorphism and thermomechanical properties of poly(L-lactic acid)/poly(D-lactic acid) blends

The effects of molecular weight (Mw) and content of poly(vinyl acetate) (PVAc) on the crystallization behaviors, competing crystallization of homocrystallites and stereocomplex crystallites (SCs), crystalline structure, and mechanical properties of poly(L-lactic acid) (PLLA)/poly(D-lactic acid) (PDLA) blends were investigated. The crystallization of PLLA/PDLA component is accelerated after the addition of low-Mw PVAc and is suppressed with high-Mw PVAc. The ability of SC formation is enhanced via blending with PVAc, irrespective of its Mw, and becomes prominent with low-Mw PVAc. The exclusive SCs are obtained in the blends with 30 mass % low-Mw PVAc. The improvement in thermomechanical property above 170 °C is ascribed to the enhancement of SC content. This work presents guidance for achieving the melt processability of SC-PLA, thus proving their potential as a high-performance substitute for conventional plastics.

Influence of the PVOH molar mass on the morphology and functional properties of EVOH/PVOH films prepared by melt blending

AbstractThe influences of the molar mass (low, medium, and high) and content of poly(vinyl alcohol) (PVOH) dispersed by melt‐blending in an ethylene vinyl alcohol (EVOH) copolymer on the morphology, microstructure, thermal, mechanical, and oxygen barrier properties were investigated. Multilayer films with external low‐density polyethylene layers and inner EVOH/PVOH blend layer and respective monolayer films were elaborated and characterized. EVOH/PVOH blends exhibited a good compatibility because of the initial presence of PVOH segments in EVOH. The detailed quantitative analysis of the morphology performed for all blends showed that the finest dispersion was obtained with the PVOH with the lowest molar mass. The properties of the films as a function of the PVOH content and its molar mass were determined herein. Significant improvement of barrier properties was obtained at moderated water activities (up to aw = 0.6) by using the PVOH with the lowest molar mass. Compared to the neat EVOH material, the oxygen permeability coefficients decreased by a factor 2 by adding 15 vol% PVOH while the thermal and mechanical properties remained similar.

Thermal analysis studies on the compatibility of furosemide with solid state and liquid crystalline excipients

In the context of the present study, the thermal behavior of furosemide and the solid state excipients, sodium alginate, poly(ethylene oxide), poly(vinylpyrrolidone), lactose mono-hydrate and magnesium stearate, using Differential Scanning Calorimetry (DSC), was probed. It was found that the thermal behavior of these solid-state pharmaceutical excipients and furosemide correlates nicely with the literature relevant data. Regarding the furosemide-excipients mixtures, the DSC scans appear as a compilation of the thermal curves of each excipient. This suggests that the formulations containing these mixtures, may retain their stability over time. This information, which arises from the cooperativity of materials, their thermal stability and behavioris very helpful for the research and development of safe and effective pharmaceutical formulations. DSC experiments were also carried out with chimeric bilayers (called ?liposomes?), composed of hydrogenated soy phosphatidylcholine (HSPC) and poly(n-butylacrylate)-b-poly(acrylic acid) block copolymer with 70 % content of poly(acrylic acid (PnBA-b-PAA 30/70) with the addition of furosemide at the molar ratio of 9:0.1:1.0 in the system HSPC:PnBA-b-PAA 30/70:furosemide. Chimeric liposomal systems were characterized as ?fluid-like? by their DSC curves, which may be potentially translated as an easy way for release of furosemide from the advanced delivery system.

BDNF elevates the axonal levels of hnRNPs Q and R in cultured rat cortical neurons

Local translation plays important roles in the maintenance and various functions of axons, and dysfunctions of local translation in axons are implicated in various neurological diseases. Heterogeneous nuclear ribonucleoproteins (hnRNPs) are RNA binding proteins with multiple functions in RNA metabolism. Here, we identified 20 hnRNPs in the axons of cultured rat cortical neurons by interrogating published axon mass spectrometric databases with rat protein databases. Among those identified in axons are highly related hnRNPs Q and R. RT-PCR analysis indicated that axons also contained low levels of hnRNPs Q and R mRNAs. We further found that BDNF treatments raised the levels of hnRNPs Q and R proteins in whole neurons and axons. BDNF also increased the level of poly(A) RNA as well as the proportion of poly(A) RNA granules containing hnRNPs Q and R in the axon. However, following severing the connection between the cell bodies and axons, BDNF did not affect the levels of hnRNPs Q and R, the content of poly(A) RNA, or the colocalization of poly(A) RNA and hnRNPs Q and R in the axon any more, although BDNF still stimulated the local translation in severed axons as it did in intact axons. The results are consistent with that BDNF enhances the axonal transport of RNA granules. The results further suggest that hnRNPs Q and R play a role in the mechanism underlying the enhancement of axonal RNA transport by BDNF.

Effect of the configuration of poly(lactic acid) and content of poly(oxyethylene) blocks to the structure and functional properties of poly(lactic acid)-block-poly(oxirane)-based nanofibrous electrospun polyester-ether-urethanes used as potential drug-delivery system.

Poly(lactic acid)-block-poly(oxirane)s (PLA-b-POE) of various compositions were prepared using a one-pot approach and then extended in a reaction with l-lysine diethyl ester diisocyanate, thereby forming polyester-ether-urethanes (PEU) with prolonged chains and units with increased degradability. The PEUs are processed by electrospinning to prepare degradable nanofibrous sheet materials with and without encapsulating the antibiotic Vancomycin (VAC). PLA block isomerism and POE blocks oligomeric content (1000 g/mol) affect the thermal properties, processability, nanofibrous sheet morphology, abiotic degradation, cytocompatibility, and encapsulated antibiotic release rate of prepared PEUs. Therefore, our findings provide an effective approach to tuning the functional properties of these advanced biocompatible materials. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2378-2387, 2019.

Effect of pore structure on gas permeability constants of porous alumina

Porous alumina was fabricated using different particle size, sintering temperature, and particle size and content of poly (methyl-methacrylate) (PMMA) as pore former. The Forchheimer equation was used to investigate the relationship between porosity and average pore size, and obtain the permeability constants k1 and k2 (the viscous effect and the inertial effect, respectively). Compared to Darcy's law, the Forchheimer equation established a more realistic and reliable relationship between fluid pressure and fluid velocity. k1 and k2 were found to be more sensitive to the average pore size than to the porosity of alumina. Moreover, reliable relationships were confirmed between the average pore size and k1, k2, and their ratio (k1/k2).

Effect of Varying Chain Length and Content of Poly(dimethylsiloxane) on Dynamic Dewetting Performance of NP-GLIDE Polyurethane Coatings.

Polyurethane coatings containingnanopools of a grafted lubricating liquid ingredient for dewetting enablement (NP-GLIDE)are prepared by curing a commercial polyol P0, a hexamethylene diisocyanate trimer, and P1- g-PDMS, which is a graft copolymer consisting of a polyol backbone P1 bearing poly(dimethylsiloxane) (PDMS) side chains. These materials are known as NP-GLIDE because most test liquids have no problem to cleanly glide off them and because segregated nanopools of the grafted lubricating ingredient (PDMS) for dewetting enablement are dispersed throughout the coating matrix. To optimize the dewetting performance of the NP-GLIDE coatings, the molecular weights of the PDMS side chains in the P1- g-PDMS samples were increased from 1.0 kDa (1k) to 5.0 kDa (5k) and 10.0 kDa (10k). A comparative study of the coatings containing three different P1- g-PDMS samples at a constant PDMS mass fraction of either 6.0 or 2.00% (m/m) showed that P1- g-PDMS5k-based coatings exhibited the best dewetting properties. These properties included the lowest sliding angles for test liquids that were incompatible with PDMS and the fastest and most effective contraction of marker ink traces and a paint. Coatings containing 0.50 and 1.00% (m/m) of PDMS5k were also prepared from P1- g-PDMS5k and compared with those containing 2.00 and 6.0% (m/m) of PDMS5k. The coatings were shown to retain their dewetting properties with the PDMS contents as low as 1.00% (m/m). Although the results of this study provided valuable insight into the design of future practical NP-GLIDE coatings, a model has also been proposed for the surface structure of the coatings to justify our observations.

Spontaneous Approach To Prepare Damping Structural Integration Materials via Gradient Plasticization Mechanism at Nanometer Scale

The gradient phenomenon is commonly seen in nature, and the gradual changes in structure could make materials with unique excellent performances compared with homogeneous materials. In this study, a novel approach to prepare damping structural integration epoxy thermosets has been developed. The damping mechanism was systematically discussed through TEM, SAXS, DSC, and DMA. It is shown that the damping property was obviously improved via the gradient plasticization at nanometer scale. Dynamic mechanical analysis showed that when the content of poly(e-caprolactone)-b-polystyrene was 40 wt %, the glass transition temperature was decreased from 171.66 to 107.84 °C while the damping temperature range (tan δ > 0.2) of the composites was broadened from 28.02 to 52.95 °C. Meanwhile, the tensile properties of epoxy thermosets were also improved when the concentration of poly(e-caprolactone)-b-polystyrene diblock copolymer was below 20 wt %. It is expected this method could provide a new idea to fabricate damping ...

Optically transparent poly(methyl methacrylate) with largely enhanced mechanical and shape memory properties via in-situ formation of polylactide stereocomplex in the matrix

Optically transparent poly(methyl methacrylate) (PMMA)-based blends with significantly enhanced mechanical and shape memory properties have been successfully prepared via in-situ formation of micro-scale polylactide stereocomplex crystallites (sc-PLA) in the PMMA matrix in this work. To achieve this goal, a certain content of poly(l-lactide) (PLLA) was firstly melt-blended with PMMA to obtain completely miscible PMMA/PLLA blends, and then an equimolar poly(d-lactide) (PDLA) was incorporated into the blends, giving rise to the in-situ formation of sc-PLA between PLLA and PDLA. In this way, the micro-scale sc-PLA particles were successfully fabricated and homogeneously dispersed in the PMMA matrix. Consequently, these resultant PMMA/sc-PLA blends possess extremely superior optical transparency, even when the content of sc-PLA reaches up to 12 wt%. A further increase in the content of sc-PLA would lead to the formation of sc-PLA network and aggregation, resulting in the deterioration of optical transparency. Moreover, the incorporation of sc-PLA micro-particles significantly enhances the mechanical property of PMMA and the maximum (≈103 MPa) of these blends demonstrates 50% increase than that (≈70 MPa) of PMMA. More importantly, it has been found that the shape recovery performance of PMMA could be effectively improved by the incorporation of sc-PLA. The optimal shape recovery ratio (86%) and high shape fixing ratio (almost 100%) can be obtained for the PMMA/sc12 blend which exhibits excellent optical transparency. It is reasonable to believe that these optically transparent blends with largely enhanced mechanical and shape memory properties possess great application potential in advanced shape memory fields.