Search

Through using modified masterbatch method which comprised the wet kneading and intercalated modifiers process, the fully exfoliated nylon clay hybrids (NCHs) were achieved. In the wet kneading procedure, the organoclay plates were easily wetting by the intercalated modifiers. Then the shearing force could completely exfoliate the organoclay with nylon 6 matrix even which only had lower molecular weight during the extrusion process. NCEs and NCAs, two series of NCHs, were prepared from the intercalated modifiers, alkylamide and polyamide, respectively. The XRD and TEM examinations show that the fully exfoliated NCHs can easily be made. The NCEs show a faster crystallization rate because alkylamide with the lower molecular length and the melting temperature act as a soft segment to make crystallization more easily and more regularly. The tensile test shows that the NCEs have higher values of modulus and yield strength and the NCAs can keep better elongation properties. Furthermore, the tensile specimen shows a cone-like fracture, which is considered more perfectly exfoliated and arranged because of the good interaction between the silicate plates and nylon 6. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

ABSTRACT A series of anatase TiO2-based nanocomposite incorporated with plasma-modified multi-walled carbon nanotubes (MWNTs) was prepared by physical blending and shows its capability for efficient electron transport when used as photoanode in dye-sensitized solar cells (DSSCs). These MWNTs characterized with good dispersal performance were obtained by functionalization technique via in situ plasma treatment and subsequent grafting with maleic anhydride (MA) onto the external walls reported previously. Compared with the conventional DSSCs, the TiO2 film with 1D carbon nanotubes possesses more outstanding ability to transport electrons injected from the excited dye within the device under illumination. As a result, at an optimum addition of 0.3 wt% MWNTs-MA in TiO2 matrix, the photocurrent-voltage ( J-V) characteristics showed a significant increase in the short-circuit photocurrent ( Jsc) of 50%, leading to an increase in overall solar conversion efficiency by a factor of 1.5. Electrochemical impedance spectroscopy analyses reveal that the MWNTs-MA/TiO2 incur smaller resistances at the photoanode in assembled DSSCs when compared with those in the anatase titania DSSCs. These features suggest that the conducting properties of the MWNTs-MA within the anodes are crucial for achieving a higher transport rate for photo-induced electrons in TiO2 layer by exhibiting lower resistance in the porous network and hence retard charge recombination that could result in poor conversion efficiency. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The use of bipolar membranes (BMs), modified by plasma-induced polymerization, as diaphragms for H2 production from water electrolysis, is discussed in this paper. The performance is demonstrated by measuring the cell voltage and rate of hydrogen production for cells operated with or without the BMs, as a function of current densities. The results of the electrochemical properties of the BMs show that the polyvinylidene fluoride-grafted 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxyl-propyl ester (PVDF-grafted-GMA-IDA) BM has great potential for water electrolysis in 0.1M KCl. As a result of characterization of the steady-state E–I curves, cell voltage reductions of up to 500 and 300mV by using the PVDF-grafted-GMA-IDA and polyethersulfone-grafted-GMA-IDA (PES-grafted-GMA-IDA) BMs, respectively, are observed at 250mA/cm2 in 0.1M KCl, compared to the water system. The efficiency of H2 production, by using the BMs grafted onto the GMA-IDA monomer as diaphragms is enhanced about 10–20% compared with the water system. In addition, the energy saved by using the GMA-IDA grafted BMs is decreased by around 10–40% at certain values of current densities. [Copyright &y& Elsevier]

Polypropylene-graft-maleic anhydride (PP-g-MAH) ionically modified with zinc(II) (PP-g-MAHZn) in varying amounts of ionic associations were prepared via melt reaction. Absorption bands in FTIR-ATR and shifted binding energy in X-ray photoelectron spectroscopy showed the formation of zinc carboxylates in PP-g-MAHZn. Decreased crystallinity, gradually increased viscosities, and storage modulus with the increment of zinc carboxylates in the PP-g-MAHZn were investigated by thermal and rheological analysis, which were attributed to the restriction of chain mobility via ionic interactions between polymer chains and aggregations of ionic domains. Furthermore, PP-g-MAHZn was introduced to polypropylene as an additive to promote foamability, and the PP/PP-g-MAHZn blends displayed higher viscosities and storage modulus compared with pristine PP in rheological measurements. In addition, the PP/PP-g-MAHZn blends were foamed by supercritical CO 2 and cryogenically fractured surfaces were observed by scanning electron microscope. PP/PP-g-MAHZn foams presented high closed-cell content, uniformity of cells, and increasing cell density owing to the combined effects of rheological properties, while maintaining the cell structures and good dispersion of the PP-g-MAHZn as nucleating sites. These results reveal that PP-g-MAHZn is a suitable additive to produce high melt strength PP for foam production. Image 1 • Polypropylene-graft-maleic anhydride ionically modified with zinc(II) (PP-g-MAHZn) in varying amounts of ionic associations. • Chain mobility was restricted by ionic interactions between polymer chains and aggregations of ionic domains in PP-g-MAHZn. • Foamability of PP was promoted by addition of PP-g-MAHZn with supercritical CO 2 as a blowing agent. [ABSTRACT FROM AUTHOR]

Hydrogenated bisphenol-A polycarbonate (PHBPA) was successfully synthesized from dimethyl carbonate (DMC) and hydrogenated bisphenol-A (HBPA) by the method of two-step polycondensation. The chemical structure and the molecular weight of PHBPA was identified by 1H-NMR spectra and gel permeation chromatography (GPC), respectively. In order to analyze the thermal degradation mechanism of PHBPA, a non-isothermal pyrolysis process was conducted and the violate products were detected using Fourier-transform infrared spectroscopy (FTIR) and gas chromatography–mass spectrometry (GC-MS). There were some reactions occurred during the pyrolysis including decarboxylation, disproportionation of the C–H transfer and β–H transfer, and the Fries rearrangement. In addition, the well-known Flynne–Walle–Ozawa (FWO) and Coats–Redfern kinetic analysis methods were used to calculate the values of activation energy and pre-exponential factors. Furthermore, isothermal pyrolysis experiments were performed and revealed that the reaction of decarboxylation occurred at 225 °C. This decarboxylation suggests that the molecular chain of PHBPA does not easily grow to a high-molecular-weight polymer. [ABSTRACT FROM AUTHOR]

Aliphatic polycarbonate (PDCM) was synthesized from dimethyl carbonate and 1,4-cyclohexanedimethanol via melting polymerization in this study. The molecular weight of PDCM was determined by gel permeation chromatography (GPC) to be ca. 49,900. The crystallization behavior and crystallinity of polyethylene terephthalate (PET) were significantly modified by adding 0.3–5.0 wt% PDCM, which was confirmed by differential scanning calorimetry (DSC), photomicrography with a heating stage and SAXS analysis. In nonisothermal crystallization kinetics analysis, the reciprocal of half-time crystallization (i.e., G parameter) for the 1.0 wt% PDCM/PET blends is 3.5 times greater than that of pristine PET at a cooling rate of 10 °C/min. Observation via polarized optical microscopy showed that the spherulites size of PET was condensed by PDCM. In addition, the fold surface energy (σ e) decreased with the presence of PDCM. According to the results of dynamic mechanical analysis (DMA) examination, the mechanical strength of 1.0 wt% PDCM/PET thin film was enhanced as the transparency still maintained above 85%, which illustrated the transparent thin film has better thermal stability and has high potential to be used such as in the electronic appliances. Image 1 • The aliphatic polycarbonate (PDCM) acted as an efficient nucleating agent for PET. • The crystallization rate of PET was enhanced 3.5 times as 1 wt% PDCM was added. • The transparent PET thin films with added PDCM exhibited great thermal stability. [ABSTRACT FROM AUTHOR]

Maleic anhydride grafted onto atactic polypropylene (aPP- g -MAH) using a solution grafting reaction with ε-caprolactam promoter was investigated in this study. FTIR-ATR and elemental analysis (EA) measurements showed that the optimal degree of grafting (DG) of aPP-g-MAH could be achieved at a 5.03 wt% when ε-caprolactam was added as the radical protecting agent. aPP-g-MAH was then introduced to PP and PP/Nylon 6 (PP/Ny6) as a nucleation and compatibility agent, respectively. The DSC curve of the PP/aPP-g-MAH blend showed that the crystallization temperature of the blend was increased to 115.3 °C, higher than that of pristine PP. In addition, POM observations demonstrated that the size of the spherulites present in pristine PP shrank obviously. Moreover, the dynamic temperature variations in the POM observations revealed that the initial crystallization temperature of PP/aPP-g-MAH was much higher than that of pristine PP. The results indicate that the aPP-g-MAH additive was an excellent nucleating agent for the PP materials. When aPP-g-MAH was added as a compatibility agent for PP/Ny6 blending, the cryogenically fractured surface of the PP/Ny6/aPP-g-MAH (5 wt%) blend presented good compatibility between PP and the Ny6 domains. The crystallization temperatures of PP/Ny6 blends with 10–50 wt% Ny6 were higher than that of pure PP, and the blends with aPP-g-MAH had much higher of that. These findings reveal that aPP-g-MAH is a good nucleation and compatibility agent in PP/Ny6 blends. Image 1 • Maleic anhydride grafting atactic polypropylene (aPP- g -MAH) can be improved by using ε-caprolactam additive. • The β-scission reaction would be suppressed by the addition of caprolactam. • Crystallization behavior of polypropylene (PP) was induced significantly by addition of aPP-g-MAH. • Compatibility between PP and nylon 6 was improved by properly added aPP-g-MAH. [ABSTRACT FROM AUTHOR]

• Triblock copolymers poly(styrene)- block -poly(isoprene)- block -poly(styrene) (PS-b-PI-b-PS, SIS) and poly(isoprene)- block -poly(styrene)- block -poly(isoprene) (PI-b-PS-b-PI, ISI) with different vinyl group contents were successfully synthesized by a simple two-step anionic polymerization using a difunctional t -BuLi initiator. • The PI domain with tunable vinyl group content was readily synthesized by adjusting the polar regulator and reaction temperature. Triblock copolymers poly(styrene)- block -poly(isoprene)- block -poly(styrene) (PS- b -PI- b -PS, SIS) and poly(isoprene)- block -poly(styrene)- block -poly(isoprene) (PI- b -PS- b -PI, ISI) with different vinyl structure contents were successfully synthesized by anionic polymerization using a difunctional t -BuLi initiator. The difunctional t -BuLi initiator was prepared from tert- butyllithium (t -BuLi) and 1,3-diisopropenylbenzene, and characterized by 1H NMR, 13C NMR, DEPT135, 7Li NMR, and GC–MS analysis. According to the results of 1H NMR, 13C NMR, and 2D HSQC analysis, the contents of 1,2- and 3,4-addition (vinyl group) structures for PI in SIS and ISI were in the range of 3.7%–94.6%, and depended on the reaction temperature and amount of tetrahydrofuran (THF) added. The M n and PDI of SIS and ISI obtained by GPC were in the ranges of 13,400–281,000 Da and 1.09–1.24, respectively. The presence of two glass transition temperatures (T g) on the DSC curve indicated microphase separation of the PI and PS domains. The low T g was attributed to the PI domain, which was correlated with the vinyl group content in the block copolymer. For vinyl group contents of 6.9% and 94.6% in the SIS triblock copolymer, and 6.6% and 94.2% in the ISI triblock copolymer, the corresponding T g values of the PI block were −64 °C and 12 °C, and −62 °C and 17 °C, respectively. [ABSTRACT FROM AUTHOR]

The bulk copolymerization of methyl methacrylate (MMA) with vinyl monomers initiated by ε-caprolactam (CL) and n-dodecyl mercaptan (RSH) was investigated. Acrylonitrile (AN) and vinyl acetate (VAc) were used to copolymerize with MMA at 90 °C in the presence of CL and RSH, respectively. As evidenced by first-order kinetics of polymerization, linear increase of molecular weights with monomer conversions, and relatively low PDI values within a range of 1.3 to 1.6, both the copolymerization reactions exhibited living characteristics. Dependences of the copolymerization on the monomer feed ratio was also studied. An increase in the feed ratio of MMA induced an increased rate of copolymerization. In contrast, an increase in the initial loading of vinyl monomer leaded to the decrease in rate of copolymerization. The reactivity ratios of each pair of comonomers were also assessed using Fineman-Ross (FR) method. The results showed that the CL has an important influence on the kinetics of copolymerization, which caused the copolymerization parameters different from the most previously reported values. [ABSTRACT FROM AUTHOR]

Shell crosslinked nanoencapsulate were prepared via crosslinking reaction between double hydrophilic grafted copolymers poly(N-isopropyl acrylamide)-co-poly(L-lysine) (PNIPAm-co-PLLys) and natural crosslinking agent genipin. These shell crosslinked nanoencapsulate possess spherical structures and the hydrodynamic radiuses are about 18.5 nm to 37.7 nm. Drug-loaded shell crosslinked nanoencapsulate were applied as drug carriers. Model drug methotrexate (MTX) were loaded into polymeric nanoencapsulate with different loading ratios (polymer / MTX = 10 / 0.5 and 10 / 1.0), then crosslinking agent genipin was added into micelle solution to form drug-loaded shell crosslinked nanoencapsulate. Entrapment efficiency and drug loading content of the drug-loaded shell crosslinked nanoencapsulate are about 12.66 wt% to 20.1 wt% and 0.84 wt% to 1.28 wt%, respectively. In-vitro drug release experiments of drug-loaded shell crosslinked nanoencapsulate were carried out in pH 7.4 phosphate buffer solution at 37 °C. All of these samples possess burst release in initial 8 h, and final accumulate MTX release amounts are about 71% to 97%. [ABSTRACT FROM AUTHOR]

Abstract In this study, we have fabricated a simple disposable electrochemical immunosensor for the point of care testing of microalbuminuria, a well-known clinical biomarker for the onset of chronic kidney disease. The immunosensor is fabricated by screen-printing carbon interdigitated microelectrodes on a flexible plastic substrate and utilizes electrochemical impedance spectroscopy to enable direct and label free immunosensing by analyzing interfacial changes on the electrode surface. To improve conductivity and biocompatibility of the screen-printed electrodes, we have modified it with gold nanoparticles, which are electrodeposited using linear sweep voltammetry. To enable efficient immobilization of HSA antibodies, we have developed novel PS/Ag/ab-HSA nanoprobes (polystyrene nanoparticle core with silver nanoshells covalently conjugated to HSA antibodies), and these nanoprobes are trapped on the electrode surface using dielectrophoresis. Each immunosensor has two sensing sites corresponding to test and control to improve specificity by performing differential analysis. Immunosensing results show that the normalized impedance response is linearly dependent on albumin concentration in the clinically relevant range with good repeatability. We have also developed a portable impedance readout module that can analyze the data obtained from the immunosensor and transmit it wirelessly for cloud computing. Consequently, the developed immunosensing platform can be extended to the detection of a range of immunoreactions and shows promise for point of diagnosis and public healthcare monitoring. Highlights • A novel electrochemical immunosensor for chronic kidney diseases (CKD). • Microelectrode surface is modified with Au nanoparticles and trapped PS/Ag/ab-HSA nanoprobes by DEP force. • A linear response to HSA concentration from 30 to 300 µg/ml which enable early detection and effective treatment of CKD. [ABSTRACT FROM AUTHOR]

The usage of green polymers are widely increased from day-to-day as detergent builders, paper-sizing agents, flocculants, thickeners, emulsifiers, and scale inhibitors due to their friendly nature with the water systems. Minimizing the formation of inorganic scale deposits in processing industrial waters presents a challenge for water treatment systems. In the present investigation, we have developed water soluble green polymers based on malic acid (MA) and citric acid (CA) through a bulk-melt condensation process and applied as water scaling inhibitors. The copolymer of poly(malic acid-citric acid) (PMC) was synthesized by varying the ratio of MA and CA monomers with 1:3, 1:1, and 3:1, and studied their descaling property with carbonate, sulfate and phosphate ions. The scale inhibition property of the homopolymers was also investigated and compared with the copolymers. As the ratio of CA was increased in the copolymer formation, there was a greater influence on the scale inhibition. Interestingly, copolymers showed the highest phosphate inhibition (98%) and have no significant change with its homopolymers. The results indicate that the synthesized green copolymers PMC were water soluble, biodegradable, non-toxic and hence, have a good water descaling property without disturbing the taste, quality and purity of water. Characterization techniques such as Fourier Transform Infrared Spectroscopy (FTIR) analysis and Thermal Gravimetric Analysis (TGA) were performed in order to understand its thermal properties and copolymer confirmation. [ABSTRACT FROM AUTHOR]

Modified masterbatch method comprising of the wet kneading and intercalated modifiers process was successfully applied to prepare exfoliated polylactic acid (PLA) clay hybrids. The crystallization rate of PLA/clay nanocomposite was improved by introducing alkylamide, an intercalated modifier with higher crystallinity. Both XRD and TEM analyses showed that the exfoliated and partially intercalated PLA nanocomposites can be obtained. The effect of clay and intercalated modifier on the nonisothermal, isothermal crystallization kinetics, and morphology of PLA was investigated using DSC instrument. The PLA nanocomposites showed faster crystallization rate because the alkylamide modifier act as a nucleation agent that successfully promoted crystallization. Notably, the crystallinity of PLA/clay hybrids dramatically increased from 9.0 to 42.1 %. The nucleation and crystal growth rate of PLA when crystallized from melt state is greatly influenced by the presence of organoclays. Therefore, as revealed from this isothermal crystallization investigation, the crystallization rate is enhanced by a factor of about 7-17. [ABSTRACT FROM AUTHOR]

Abstract: A novel in situ chemical precipitation method to directly synthesize CdS nanocrystal arrays in the presence of microporous templates of poly(glycidyl methacrylate-grafted-3,3′-dimethyl-(4-hydroxyphenylazanediyl) bis(2-methylpropanoate))-random-polystyrene (PGHS), which were formed by self-assembling dendritic-linear PGHS copolymers via the solvent-induced phase separation process, were investigated. The surface morphology of the PGHS template and the spatial positions of the CdS nanocrystals in the PGH-CdS could be easily and quickly controlled by altering the content of the dendritic GMA-HPAM segments. The diameters of the CdS nanocrystals on the PGHS-CdS template were uniform in the range of 3–4nm. Large-area, hexagonally ordered CdS nanocrystal-array domains were discovered in the PGHS2-CdS template used in this study. [Copyright &y& Elsevier]

Abstract: A series of dendritic-linear copolymers, composed of poly(glycidyl methacrylate-grafted- 3,3′-dimethyl-(4-hydroxyphenylazanediyl) bis(2-methylpropanoate))-random-polystyrene (PGMA-HPAM-r-PS), were successfully synthesized via a macromonomer route. Characterization of the copolymers and investigation of their thermal behavior revealed a significant influence of the dendritic GMA-HPAM segment. The thermal degradation temperature (T d) of the dendritic-linear PGMA-HPAM-r-PS copolymer was elevated as the weight percentage of dendritic segment (GMA-HPAM) increased. The glass transition temperatures of the copolymers exhibited a strong, complex dependence on the dendritic GMA-HPAM segment, with three behavioral ranges. DSC data were attributed to two distinct effects of the dendritic segment: (i) the effect of the dendritic segment grafting on copolymer chains, and (ii) intermolecular interactions between the dendritic and styrene segments. Microporous dendritic-linear PGMA-HPAM-r-PS copolymer matrices were prepared using solvent-induced phase separation at room temperature. The self-assembled surface morphology was affected by (i) the micellar domains of the dendritic and styrene segments and (ii) inter- and intramolecular interactions between the dendritic and styrene segments. An interesting relationship between thermal behavior and surface morphology was discovered, which can provide a simple, accurate and rapid means of finding the optimum dendritic segment content for producing a hexagonally ordered microporous matrix for different dendron generations. [Copyright &y& Elsevier]

Abstract: We used ionic poly((methyl methacrylate)-co-(methacrylic acid)) (PMA-MAA) copolymer spheres (500nm) as a core template, synthesized using a soap-free emulsion polymerization method, to prepare monodispersed hollow nanocomposite spheres (HNCS). Ceramic type (CoFe2O4/SiO2) HNCS and metallic type (CoSiO2) HNCS were prepared by calcining PMA-MAA/CoFe2O4/SiO2 hybrid core/shell composite spheres in air and a reducing gas, respectively. The crystalline phase involved in ceramic HNCS had a cubic spinel ferrite structure with an average crystallite size between 3.4 and 10.5nm, while the phase embedded in the metallic HNCS revealed a body-centered cubic structure with an average crystallite size of 28.7nm. Scanning electron microscope and transmission electron microscope photographs show that the hollow spheres were uniform and had a shell thickness of about 40nm. Based on an energy-dispersive X-ray line scan composition analysis of a cross-section of hollow spheres it was found that the SiO2 not only coated the surface of the spheres, but was also distributed over the shell of the hollow spheres. The HNCS exhibited hysteresis loops of a ferromagnetic nature, and coercivity and saturation magnetization varied with the size of the magnetic nanoparticles embedded in hollow spheres. The magnetic properties of HNCS were also evaluated as a function of temperature. [Copyright &y& Elsevier]

Abstract: Partially crystalline bisphenol A polycarbonate (BPAPC) nanofibers were successfully fabricated using a combination of a centrifugal field (1800rpm) and an electrostatic field (25kV). The BPAPC solution properties are key factors for adequately electrospinning the partially crystalline BPAPC nanofibers. The correlation times (τ c) of methyl (τ c =9.3 ns) and of benzene-ring (τ c =15.3 and 15.8 ns) motions in the 14wt.% BPAPC/THF solution were longer than in CH2Cl2 and CHCl3, as determined by NMR. The distribution-peak maximum of the hydrodynamic radius of BPAPC in the 14wt.% THF solution (R h =15Å) was higher than in CH2Cl2 (R h =9.2Å) and CHCl3 (R h =7.9Å), as evidenced by DLS data. We conclude that the BPAPC assumed a denser, more worm-like chain conformation in THF solvation. [Copyright &y& Elsevier]

Abstract: In this study, 2-methacryloxyethyl phenyl phosphate (MEPP), a phosphorus-containing flame retardant, was synthesised via the esterification of phenyl dichlorophosphate (PDCP) with 2-hydroxyethyl ethylene methacrylate (HEMA), followed by hydrolysis. A two-stage bulk polymerisation process prepared MEPP/methyl methacrylate (MEPP/MMA) copolymers containing various amounts of MEPP. The condensed-phase and volatized products produced at various temperatures during the thermal degradation of MEPP/MMA copolymer were monitored by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis with Fourier transform infrared spectroscopy (TGA/FT-IR). Finally, we propose the possible mechanisms for the thermal degradation of MEPP/MMA copolymer according to the analytical results of the condensed-phase and volatilized products. [Copyright &y& Elsevier]

Novel thermoplastic polyurethanes with chelating groups were synthesized from 4,4′-diphenylmethane diisocyanate (MDI), poly(ethylene glycol) (PEG), and EP-IDA. Differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR), and impedance spectroscopy (IS) were used to monitor changes in the morphology of these polyurethanes with the concentration of lithium perchlorate (LiClO4) dopants. Adding the salt significantly changes the FTIR spectrum of the polyurethane, indicating an interaction between the lithium cation within the urethane group and the chelating group. The soft segment Tg increases with LiClO4 concentration, as determined by DSC, indicating that solubility of the lithium cation in the host polyurethane increases with the chelating groups. IS shows that the bulk conductivity reaches a maximum as the salt concentration is increased. One of the investigated polyurethane electrolytes has an ionic conductivity as high as ∼10−6 S cm−1 at room temperature. [Copyright &y& Elsevier]

A series of aliphatic oxalate-polycarbonate polyols (AOPC) was synthesized from dimethyl carbonate, 1,6-hexanediol, and diethyl oxalate, made from oxalic acid that is a kind of bio-based material, via melting polycondensation. The aliphatic polycarbonate-based polyurethanes with oxalate units (AOPCUs) were successfully prepared using the AOPCs and hexamethylene diisocyanate (HDI) with 1,4-butanediol (1,4-BD) as the chain extender. The results of the 1H NMR analysis showed that the Mn of AOPCs was approximately 2900. Whereas, the Mw of the AOPCUs was ca. 48,200–53,000 from the gel permeation chromatography (GPC) measurement. The oxalate unit effectively impeded the crystallization of the AOPCUs as shown in the Differential scanning calorimetry (DSC) analysis. Based on the stress-strain curves, the AOPCUs with 10 M ratio of oxalate unit had best strength and elongation at break; however, their Young's modulus decreased from 130 MPa to 26 MPa. In addition, the biodegradation of the AOPCUs was studied using the fungi, Aspergillus sp. and Fusarium sp. The more oxalate units in the AOPCUs, the better biodegradability they presented after the 84-day degradation test. The characteristics of the biodegradation analysis for the AOPCUs presented the bulk erosion, and the oxalate unit played an important role in their biodegradability. Image 1 • Polycarbonate-based polyurethanes with oxalate unit (AOPCUs) were synthesized. • The oxalate unit impeded the crystallization of AOPCUs based on DSC curves. • AOPCUs with more oxalate unit have lower melting temperature and melting enthalpy. • Strain hardening behavior occurred readily for AOPCUs with oxalate unit. • The biodegradability of AOPCUs by fungi was enhanced by the oxalate unit. [ABSTRACT FROM AUTHOR]

The functional polymer (PMA- co -MAA) latex microspheres were used as a core template to prepare magnetic hollow spheres consisting of CoFe 2 O 4 /SiO 2 composites. The spinel type crystal structure of CoFe 2 O 4 ferrite is formed under annealing, whereas the polymer cores are completely removed after annealing at 450 °C. Magnetic and Mössbauer spectroscopy measurements reveal very interesting magnetic properties of the CoFe 2 O 4 /SiO 2 hollow spheres strongly dependent on the particle size which can be tuned by the annealing temperature. In the ground state of low temperatures, the CoFe 2 O 4 nanoparticles are in antiferromagnetic state due to the canted magnetic structure. Under heating in the applied field, the magnetic structure gradually transforms from canted to collinear, which increases the magnetization. The Mössbauer data revealed that the small size CoFe 2 O 4 /SiO 2 particles (2.2–4.3 nm) do not show superparamagnetic behavior but transit from the magnetic to the paramagnetic state by a jump-like magnetic transition of the first order This effect is a specific property of the magnetic nanoparticles isolated by inert material, and can be initiated by internal pressure creating at the particle surface. The suggested method of synthesis can be modified with various bio-ligands on the silane surface, and such materials can find many applications in diagnostics and bio-separation. [ABSTRACT FROM AUTHOR]

SiC nanowires (NWs) and nanoparticles (NPs) fabricated by carbothermal reduction of rice straws with/without FeSi catalysts were characterized by transmission electron microscopy to study the catalyst-facilitated vapor-liquid-solid (VLS) growth against the oriented attachment of the crystals, which underwent 2H- to 3C-type transformation. The cotectic melt of the FeSi catalyst in the Fe-Si-C-O system turned out to promote the VLS growth to form straight and occasionally tapered NWs in contrast to the zigzag ones via the ( hkl )-specific coalescence of the faceted NPs. The SiC NWs showed [0001] 2H -directed growth more or less stacked with {111} 3C interlayers following the optimum crystallographic relationship (0001) 2H //{111̅} 3C ; [21̅1̅0] 2H //⟨101⟩ 3C with zigzag {111} 3C lateral steps and polysynthetic twins/faults near the (0001) 2H /(111) 3C interface. The FeSi-assisted VLS growth and twinning/stacking fault-coupled 2H to 3C phase change may be extended to novel green manufacturing and design of sustainable resources for other semiconductor NWs., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

A novel method to prepare Ag dendrites on the surface of polymer membranes, which was synthesized by using the soap-free emulsion copolymerization of n-butylacrylate (BA) and acrylonitrile (AN), as well as 2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxy-propyl ester (GMA-IDA) that was used as a chelating group, is presented in this study. The characteristics of polymer membranes were investigated by Fourier transform infrared (FT-IR) spectroscopy and elementary analysis (EA). The weight fraction of the chelating group (GMA-IDA) in the polymer was 4.2% as revealed by elemental analysis. The chelating group, -N(CH(2)COO(-)Na(+))(2) on the polymer was used to coordinate nickel(II) ions, whose chelating amount was estimated by an atomic absorption spectrophotometer (AA). The coordinated Ni(2+) ions were subsequently reduced to nickel nanoparticles, which functioned as templates for growing Ag dendrites from aqueous solution of Ag(+)/poly(vinyl pyrrolidone) (PVP) aqueous solution. The phase identification of the Ag dendrites was confirmed by X-ray diffraction (XRD). Scanning electronic microscopy (SEM) showed the averaged dimension of Ag dendrites was about 2-3 microm in length and ca. 100 nm in diameter. Moreover, the amount of Ag dendrites increased with the decreasing PVP concentration present in the aqueous solution. The energy dispersive X-ray spectrometer (EDX) reveals that the formation of the Ag dendrites was chiefly through the redox reaction of nickel nanoparticles and Ag(+) ions, namely galvanic reaction., (Crown Copyright (c) 2010. Published by Elsevier Inc. All rights reserved.)