Search

In this research, both commercially available (Cloisite 93A) and advanced functionalized clay mineral were used to obtain clay–epoxy nanocomposites. Cloisite 93A was modified with three different alkoxysilanes and was incorporated in Epon 862 epoxy resin which was crosslinked using tetraethylenepentamine as a curing agent. The determination of color grades of the composite samples was followed. The morphology of the composites was analyzed using X-ray diffraction and ESEM micrographs which provided insight into the fracture mechanism. Thermal behavior was evaluated by TGA and DSC and thermo-mechanical properties of the cured samples have been evaluated by DMA technique. The data indicated that intercalated or agglomerated silylated Cloisite–epoxy nanocomposites were obtained. The silylated Cloisite samples are more compatible with the polymer matrix due to their enhanced hydrophobic behavior leading to an improvement in storage modulus and stiffness but also to the increase of glass transition temperature up to 30 °C.

The effect of orientation induced during the manufacturing process on the self-assembled morphology and mechanical properties of poly(styrene-b-ethylene/butylene-b-styrene) block copolymer (SEBS), maleated SEBS (SEBS-MA) and their composites with graphite was examined in this paper. The roll milling process induced higher stiffness along the rolling direction, emphasized by the increase of Young’s modulus with 645% in this direction relative to the perpendicular one and the increase of storage modulus at room temperature with one order of magnitude. The addition of graphite particles diminished the anisotropy of static and dynamic mechanical properties but contributed to the increase of the total energy absorbed till break. The different self-assembled morphologies and degree of order observed by polarized optical microscopy (POM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) in SEBS and SEBS-MA explained some of the differences in their static and dynamic mechanical behavior. For the first time the anisotropy was emphasized by the different glass transition values obtained on the two stretching directions.

We focused on preparing cellulose nanofibrils by purification, separation, and mechanical treatment of Kombucha membranes (KM) resulted as secondary product from beverage production by fermentation of tea broth with symbiotic culture of bacteria and yeast (SCOBY). We purified KM using two alkaline solutions, 1 and 4 M NaOH, which afterwards were subjected to various mechanical treatments. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) were employed to evaluate the purification degree, the size and aspect of cellulose fibrils after each treatment step, the physical-chemical properties of intermediary and final product, and for comparison with micro-crystalline cellulose from wooden sources. We determined that 1 M NaOH solution leads to approx. 85% purification, while a higher concentration assures almost 97% impurities removal. XRD analysis evidenced an increase in crystallinity from 37% to 87% after purification, the characteristic diffractograms of Iα and Iβ cellulose allomorphs, and a further decrease in crystallinity to 46% after microfluidization, fact correlated with a drastically decrease in fibrils’ size. FTIR analysis evidenced the appearance of new chain ends by specific transmission bands at 2941 and 2843 cm−1.

Obtaining composite materials based on multiwalled carbon nanotubes (MWCNT) from water dispersion is viable nanotechnology with low impact on the environment and with concrete directions for advanced materials used in coating application. Emulsion, miniemulsion, or microemulsion polymerization techniques can offer by their nature the reducing of the interfacial tension (between MWCNTs and monomers). By free radical polymerization, MWCNT-polymer composites can be obtained in a greener manner by cutting off several supplementary technological steps involved by functionalizing (toxic reagents, energy consuming), solvent phase purification, and separation of the fillers. Providing such examples involving large tonnage polymers like polystyrene, SAN copolymer, polyacrylonitrile, poly(methyl methacrylate) and other, a detailed picture of the state of the art can be achieved for synthesis and application in automotive industry, aerospace, coating materials, antistatic materials, sensors, actuators, membrane production, fibers industry, and others. The chapter tries to answer to some technological bottlenecks: decreasing the environment impact and extending the areas of application by reducing the costs of MWCNTs processing for polymer composites as a natural step for the sustainable development of an MWCNT-composite industry.

The aim of this paper was to prepare composites of bacterial cellulose (BC) and collagen to evaluate both the effect of collagen on the morphological, mechanical and thermal properties of BC and the effect of BC on the thermal stability of collagen for designing composites with increased potential biomedical applications. Two series of composites were prepared, the first series by immersing BC pellicle in solutions of collagen obtained in three forms, collagen gel (CG), collagen solution (CS) and hydrolysed collagen (HC), followed by freeze drying; and the second series of composites by mixing BC powder in solutions of collagen (CG, CS and HC), also followed by freeze drying. The properties of obtained composites were evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), mechanical tests, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results revealed that BC acts as a thermal stabilizer for CS matrix, while with CG matrix it interacts synergistically leading to composites with improved properties. On the other hand, the BC sheet impregnated with collagen has a significantly improved thermal stability. Collagen (as HC, CS or CG) has also a positive influence on the mechanical properties of lyophilized BC sheet. A four times increase of modulus was observed in BC/HC and BC/CG composites. and an increase of 60 times for BC/CS. The spectacular increase of elastic modulus and tensile strength in the case of BC/CS composite was explained by the easier penetration of collagen solution in the BC network and impregnation of BC fibrils as revealed by SEM and AFM analyzes.

The increased interest in silica nanowires for nanophotonics, mechanical applications, microsurgery, chemical and biological sensors strongly motivates the search for new discoveries involving complex silica nanowire-clay mineral layers (SiNW), particularly focusing on their growth mechanism, their involvement during polymer synthesis and the generation of a new class of polymer nanocomposites. This paper addresses the major findings involving the growth mechanism of silica nanowires on the clay mineral layers as well as their high segmental mobility and influence on the kinetics of butylacrylate mini-emulsion radical polymerisation. The growth mechanism for the silica nanowires was a sol-gel process involving tetraethylorthosilicate at the edge groups of the clay layers after blocking the reactive sites with a monofunctional alkoxysilane. To demonstrate the mobility of the network, an indirect method was utilised, specifically the interaction between the ethoxylated molecules and Tween 60. No cross-linking side effects occurred in the silica nanowires. SiNW enhance the free radical polymerisation of butylacrylate in dispersed media, increasing the monomer conversion from 2.5% to 33%. The kinetics of the polymerisation process can be tuned by SiNW, modulating the system between emulsion- and mini-emulsion-like systems by acting on the pseudo-steady state interval of the radicals (10%–40% conversion).

This paper reports the synthesis of coating silica particles, in order to design hybrid materials with hydrophobic surface properties. The silica particles were prepared in basic conditions under atmosphere of carbon dioxide (CO 2 ), using tetraethylorthosilicate (TEOS) as a precursor and octyltriethoxysilane (OTES) as a surface modifying agent. It was demonstrated that the contact angles of silica hybrid films could be changed by varying temperature and pressure of CO 2 . The investigation of the prepared hybrid materials by dynamic light scattering (DLS) and environmental scanning electron microscopy (ESEM), respectively, showed that they consisted mainly of particles with a diameter of 100–250 nm. Fourier transform infrared (FT-IR) spectra indicate that the interaction between the coupling reagents, at different conditions, is mainly through chemical bonding.

The objective of this study is to design new hybrid silica materials as templates with hydrophobic properties, prepared at room temperature by a base catalyzed sol–gel process. As silica sources, organoalkoxysilanes functionalized with short hydrophobic chains were used: tetraethylorthosilicate (TEOS), methyltriethoxysilane (MTES), vinyltriethoxysilane (VTES), octyltriethoxysilane (OTES) and isobutyltriethoxysilane (iTES). It was shown that hydrophobicity of the functionalized silica nanoparticles increased as a function of length of the aliphatic chains (MTES < iTES < OTES) or when, instead of a hydrophobic alkyl chains (substituting group of silica precursors), a monounsaturated group was used (VTES). It was observed that the samples responded in a specific way to each type (hydrophilic or hydrophobic) of the dropped liquid. Even though the experiments were limited to short hydrocarbon chains, they showed that there is a threshold to reach high hydrophobicity of the hybrid surface.

In this report, we present the versatile and effective technique, using environmental friendly reductant glucose, to prepare stable silver nanodispersions by reduction of Ag+ ions. Alternant copolymers of maleic anhydride with vinyl acetate and styrene sulphonate sodium acid salt polyelectrolytes were synthesized in aqueous solution and used as stabilizers. The formation of nano silver particles was confirmed by UV-Vis spectrophotometry and TEM measurements. Dynamic Light Scattering (DLS) measurements were needed to study how the reagents and their concentrations influence particle size. SEM images show the nanostructure of the hybrid films and indicate a strong interaction between the polyelectrolyte and the silver NPs. Moreover, the silver NPs could be stored for one year without observation of aggregates or sedimentation. The final solid products obtained after evaporating to dryness can be used to produce stable dispersions upon mixing with water. Few of the final products were found to exhibit a high antibacterial and antifungal activity.

Modifications to the refractive indices of meso-structured organic–inorganic films caused by variations in the mole fraction of precursors in ethanolic solutions were investigated. The refractive indices were dependent on the mole fraction of C16TMS (hexadecyltrimethoxysilane) and of the C16TMS/TMOS (tetramethoxysilane) (1/1) mixture in ethanol. The dependency was determined to be nonlinear, and the phenomenon was attributed to self-assembly caused by the long alkyl groups (C16) on the C16TMS. Changes in the maximum decreasing rate of dn/dx values [(dn/dx)max—for dn/dx estimation, the curves from Fig. 1 were associated with a polynomial; using a dedicated program, dn/dx was calculated; maximum values of dn/dx were taken into account and were included in Table 1)] were used to distinguish the behavior of alcoholic precursor mixtures. In the case of using pyrene as a fluorescent probe, the ratio between two peaks from the pyrene emission spectra (I1/I3) strongly decreased as hydrophobic micro-surroundings formed due to the self-assembly process. The UV–VIS spectra of a cationic dye solution, R6G, was studied because dilute solutions of the dye in equilibrium form measurable ratios of dimers and monomers. The absorbance was modified as micro-surroundings with different polarities were formed. These three methods demonstrated that nano-structuration was present prior to the occurrence of the sol–gel process. The combination of C16TMS with other alkyltrialkoxysilane precursors having hydrocarbon chain lengths between C1 and C8 provided further evidence for a nonlinear dependence of the refractive indice and fluorescence spectra of pyrene. The properties of the final hybrids obtained by the sol–gel process were significantly affected by the precursor hydrocarbon chain lengths. DSC, XRD and FTIR measurements were used to show the plasticizing phenomena of C16 as other alkyltrialkoxysilanes (i.e., C1–C8) were added.

This study is aimed at developing an innovative approach for Indigo Carmine dye removal from synthetic solutions by electrodialysis, carried out using ion exchange membranes. The batch electrodialysis system was operated at various current intensities: 0.05, 0.1 and 0.15 A. The pH and conductivity of solutions were measured before and after using electrodialysis process. The colour removal efficiency (CR %) was determined by spectrographic analysis and the energy consumption (EC) was calculated. The obtained results show that the pH of treated solution increases due to the increase in solution conductivity. Moreover, the values of CR % and EC increase when increasing current intensity. The optimal value was obtained at 0.15 A (CR > 97%). The membranes were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy.

Magnetite alternating copolymers divinylbenzene–maleic anhydride (DVB–MA) composites were prepared by dispersion polymerization. Because magnetite is used as a complex with oleic acid (Fe3O4OLA), the final hybrids show good dispersion of inorganic nanofillers in the polymer matrix. The obtained composites were analyzed by infrared absorption spectrometry, diffuse reflectance in visible light, thermogravimetry, X-ray fluorescence, X-ray diffraction, dynamic light scattering, scanning electron microscopy and vibrating sample magnetometry. The obtained results indicate the successful preparation of magnetite nanoparticles with an average size of about 23 nm dispersed in micrometer size copolymer spherical particles, which relative content can be controlled via the processing parameters. A relationship between the relative content of magnetite nanoparticles and the size of the polymer particles, with direct influence on the diffuse reflectance in the visible domain, was observed. A superparamagnetic behavior was evidenced at room temperature with a blocking temperature lower than as expected from the bulk anisotropy constant and the average size of the magnetite nanoparticles. Both the unexpected low blocking temperature and the observed low specific magnetizations were explained by a defected and poor crystalline structure of the magnetite nanoparticles, giving rise to spin disorder and diminished crystalline anisotropy constant.

This paper reports the synthesis of hydrophobic and antireflective coatings by sol–gel process at room temperature (25 °C), using tetraethylorthosilicate (TEOS) as a precursor and methyltriethoxysilane (MTES), phenyltriethoxysilane (PTES), vinyltriethoxysilane (VTES), and octyltriethoxysilane (OTES) as surface modifying agents. The silica sol was prepared by keeping the molar ratio of TEOS:RTES at 1:1, in acidic conditions with ethanol and 0.1 M HCl. All hybrid systems were enriched with titanium(IV) isopropoxide as the cross-linking agent. It was observed that the obtained silica films become hydrophobic with the introduction of the hydrophobic organic group. The higher value of static water contact angle (107 ± 3°) was obtained for the silica film prepared with TEOS + OTES. Under optimal synthesis condition, we obtained antireflection coatings, exhibiting a low reflection in the visible range.

Sodium montmorillonite (NaMMT clay) derivatives were encapsulated in polymer particles obtained through dispersion copolymerization of divinyl benzene (DVB) with maleic anhydride (MA). To evidence the effect of alkyl monoalkoxysilanes upon MMT reaction, a variety of MMT clay functional derivatives were investigated. Particles with an increased size of modified MMT clay dispersed in dichloromethane were obtained using alkyl monoalkoxysilanes with a longer hydrocarbon chain. Relatively long hydrocarbon chains can exhibit a low substitution degree of MMT clay with alkyl monoalkoxysilanes. MMT class with a low substitution degree leads in the presence of alkoxysilanes to particles with average size between 700 and 1200 nm, and when DVB–MA copolymer is added the particles size decreases (~480 nm). The influence of layered silicates on the thermal stability of DVB–MA copolymer as a function of the used vinyl siloxanes derivatives for functionalization of MMT, on one hand, and the nonlinear variation of refractive index of used silanes on the other hand, pointing out the autoassociation during initial reaction of substitution.

Polymers filled with inorganic nanoparticles have become interesting materials as dielectrics because of their improved mechanical and electrical properties compared with the unfilled polymers and with polymer microcomposites. These improvements are mainly due to the large surface area of nanoparticles and new polymer–nanofiller interface characteristics. In the present work, polyethylene nanocomposites with SiO2 and Al2O3 nanoparticles were prepared by melt mixing. Mechanical and electrical properties of these composites were determined and morphological aspects were revealed by scanning electron microscopy, wide-angle X-ray diffraction, and atomic force microscopy. The effect of nanostructure and the importance of nanofiller dispersion were analyzed in connection with mechanical and electrical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

New nanocomposites based on polyacrylates and five types of montmorillonites modified by edge covalent bonding, were obtained. The alkoxysilanic substituent strongly influenced the physical–chemical properties of the final material. All modified clay minerals exhibit a lower wettability compared to pure montmorillonite. FTIR and TGA analyses confirmed the incorporation of montmorillonite in the polyacrylate matrix. Rugged spherical particles indicated that the platelets were predominantly on the polymer particles.

Nanocomposites from polyethylene and TiO2 with different shape and size were prepared by direct mixing and masterbatch dilution, respectively. The mechanical properties of nanocomposites were determined and discussed in relation to the nanofiller dispersion. Moreover, the morphological aspects of polyethylene with and without nanofiller were revealed by means of SEM and WAXD. A better dispersion of the nanoparticles and increased mechanical properties were observed in the case of the masterbatch method. No important differences in mechanical and morphological characteristics of anatase and rutile containing polyethylene composites were observed, except a higher increase of the elastic modulus in case of anatase-containing composites.

Nanocomposites of divinylbenzene-maleic anhidride (DVB-MA) copolymers were synthesized in aqueous medium by generating silver nanoparticles from AgNO3-NaBH4 reaction. SEM images evidence the forming of metal nanoparticles on the particles surface of DVB-MA copolymers. The copolymer particles have larger diameters in the presence of monoesther maleic of nonyl phenol ethoxylate or sodium montmorillonite than DVB-MA copolymer particles although the nanoparticles' forming is still possible. The average size and the Zeta potential of the hybrid particles decrease in water, toward the initial copolymers sustains the forming of nanocomposites with Ag nanoparticles on the surface.

The sol–gel synthesis strategies combined with the templated growth of organic–inorganic hybrid networks provide access to an immense new area of innovative multi-functional advanced materials. One possible way to prepare such new advanced materials is to encapsulate liquid active agents (such as monomers, dyes, catalysts and hardeners) in microcapsules. Silica microcapsules of tetraethylortosilicate (TEOS) and 3-(trimethoxysilyl)propyl methacrylate (MPTS) were prepared in a precursor-monomer/NH4OH water microemulsion system. Trimethylolpropane triacrylate (TMPTA)—a trifunctional monomer useful in manufacturing of coatings, inks and adhesives—and a corresponding photoinitiator (DAROCUR 1173) were entrapped inside the obtained microcapsules. MPTS was used to increase compatibility between TMPTA and the sol–gel precursors. As stability agent we added a “home made” product resulted from functionalization of poly (ethylene glycol) methyl ether (MPEG) with (3-isocyanatopropyl) triethoxysilane (NCOTEOS). Were obtained microcapsules containing incorporated monomer and having average particle size in range of 0.5–50 μm. Thermal analysis, morphology study and the increase of the silica microcapsules average diameter, measured by DLS technique confirm the monomer encapsulation.

From an environmental and cost-effective perspective, a number of research challenges can be found for electronics, household, but especially in the automotive polymer parts industry. Reducing synthesis steps, parts coating and painting, or other solvent-assisted processes, have been identified as major constrains for the existing technologies. Therefore, simple polymer processing routes (mixing, extrusion, injection moulding) were used for obtaining PMMA/HNT nanocomposites. By these techniques, an automotive-grade polymethylmethacrylate (PMMA) was modified with halloysite nanotubes (HNT) and an eco-friendly additive N,N&prime, ethylenebis(stearamide) (EBS) to improve nanomechanical properties involved in scratch resistance, mechanical properties (balance between tensile strength and impact resistance) without diminishing other properties. The relationship between morphological/structural (XRD, TEM, FTIR) and tribological (friction) properties of PMMA nanocomposites were investigated. A synergistic effect was found between HNT and EBS in the PMMA matrix. The synergy was attained by the phase distribution resulted from the selective interaction between partners and favourable processing conditions. Modification of HNT with EBS improved the dispersion of nanoparticles in the polymer matrix by increasing their interfacial compatibility through hydrogen bonding established by amide groups with aluminol groups. The increased interfacial adhesion further improved the nanocomposite scratch resistance. The PMMA/HNT-EBS nanocomposite had a lower coefficient of friction and lower scratch penetration depth than PMMA/HNT nanocomposite.

Synthesis of nanocomposites based on polystyrene/polybutylacrylate with layered silicates using emulsion polymerization procedure in aqueous medium allowed obtaining stable nanolatexes with sodium dodecyl sulfate as surfactant. Monomer and layered silicate nature influences the average diameter of the particles and the zeta potential appeared on the particle-disperse medium interface, as it was shown by dynamic light scattering analyses. In order to evidence the layered silicate structure, two structural evaluation methods were used. A new approach was used based on Fourier transform infrared analyses as a method to asses the clay delamination. The method was followed in conjunction with X-ray diffraction patterns and showed the pronounced delamination of the clay in the polymer matrix. The thermal stability was investigated by thermogravimetric analyses and the morphologies in solid state observed by environmental scanning electron microscope measurements.

The aim of this work was to select a fungal strain with degradative potential upon PVA based materials. The polymeric materials tested were PVA films which contain different percentages of PVA, starch and glycerol. These materials are of interest for food packaging applications, which presume to solve the problems concerning accumulation, disposal and degradation. Eleven strains were tested in solid culture for the ability to use PVA based composites as carbon and energy sources. The fungal strain selected was cultivated in liquid medium with different compositions. The scanning electron microscopy (SEM) investigations revealed the effects of microorganism growth upon polymeric films. Significant changes in polymer surface aspects were observed depending on the medium culture composition, the presence of supplementary carbon source facilitating microbial growth and degradation process.

A polymer encapsulated fertilizer, in urea-formaldehyde matrix, was prepared and tested. The fertilizer was obtained in solid form, through a two-stage process, and was tested for activity index and degree of leaching in soil. Analyses were performed using modern techniques, such as 1H-NMR, FT-IR or SEM. The process leads to high yields of microcapsules, both in terms of quantity of microcapsules and content of nutrients. The product presented very good characteristics for use in controlled fertilization.

We report surfactant-free emulsion polymerization of styrene by using five types of montmorillonite modified by grafting monofunctional alkoxysilanes. Dynamic light scattering (DLS) determinations were strongly influenced by the presence of modified montmorillonite. FTIR and XRD spectra confirmed the incorporation of montmorillonite in the polymer matrix. The morphology of the latex particles was changed. Spherical and snowman particles indicated that the platelets were both inside and outside of the polymer particles.

Styrene (St) and butyl acrylate (BuA) microemulsion polymerizations were investigated in presence of layered silicates (LS) and sodium dodecyl sulfate (SDS) as surfactant. Two main LS categories were used: one in the sodium form as Na montmorillonite (MMT) and the other in organomodified form LS (OLS) with quaternary ammonium salts having different hydrophobic modifiers. The swelling capacity of OLS in presence of monomers with different polarity is more pronounced for partners with closer hydrophobicity to St. The latexes obtained by microemulsion polymerization showed larger particles size for BuA polymer and BuA copolymer with sulfonated styrene than for St. Analyzing the dried hybrid polymers by XRD, we found structures which corresponds to exfoliated LS. The thermal behavior of hybrids, examined by TGA, showed higher rates of decomposing temperatures in the case of OLS, in comparison with the NaMMT hybrids. The obtained hybrids were evaluated by DLS, FTIR, DSC, and SEM.

It was studied the polymerization of styrene (St) and of butyl acrylate (BuA) in nonionic microemulsions in the presence of a layered alumino silicates, montmorilonit (MMT) type. In time, the latexes separate in two distinct strata, MMT being distributed in the inferior strata where forms aggregates with on order of size bigger than the diameters of nanoparticles of latex. The solid products obtained are nanohybrids of intercalate type whose structural order increases direct proportional with the increase of hydrophobic character of the quaternary ammonium salts used for organophilization of MMT. The presence of nonionic surfactant, nonyl phenol with 25 mols of ethylene oxide, intercalated between the lamellar strata of MMT produces the decrease of thermal stability of hybrids and decreases the glass transition temperature of PSt which is more compatible than PBuA.

New hybrid materials based on polyether polyols were prepared by using a sol-gel reaction of alkyltriethoxysilanes, in the presence of propylenoxide-ethylenoxide trifunctional block copolymers. The resulting composites are transparent and have a filmogene behavior. Two types of filler systems were used: one based on silane precursors and one based on both the silane precursors and nanoclay (sodium montmorillonite). FT-IR spectra were evaluated to prove both the covalent interaction at the functional groups level and the presence of silica nanodomains formed by sol-gel process. The polarity changes were analyzed in the UV spectra, which shift according to the nature of different cationic dyes. Polyether hybrids were also obtained in the presence of some layered silicates. The X-ray diffraction reflects the changes in basal spacing of the Cloisite Na+, when it is added to different formulations. The modification of film morphology, depending on the reactants nature, can be observed in the SEM images.

The styrene (St), butyl acrylate (BuA), and methyl methacrylate (MMA) polymerization in microemulsion in the presence of sodium dodecylsulfate is studied. This process is conducted in the presence of some comonomers having groups that can participate in sol–gel processes: 3(trimethyloxysilyl) propyl methacrylate (MPTS), triethoxy vinylsilane (VTES), and a comonomer with a sulfate group, styrene sodium sulfonate (StSO3Na). It has been observed that stabile latexes are obtained by radical polymerization at pH = 7, followed by a sol–gel process in the presence of ammonia. Latex particles sizes and zeta potential grow with MTPS concentration and in StSO3Na presence. VTES effect depends on its reactivity in St, MMA, and BuA copolymerization. Glass transition temperature and thermal decomposing temperature are influences by functional comonomer concentration and chemical structure. The Fourier transform infrared spectrum and inorganic residue growth after organic part thermal decomposition shows the presence of silica in obtained latexes.

Polymer composites with cellulose microfibrils are materials with unique properties compared to existing materials: high strength, formability, and geometrical complexity at very small scale, low density, and abrasivity, biomedical compatibility, and possibility of recycling. Polymer composites from polypropylene and two types of cellulose microfibrils were prepared and characterized. To enhance the compatibility of cellulose microfibrils with polypropylene matrix, a silane-coupling agent and a modified polypropylene were used. Depending on the applied method, composite materials with enhanced mechanical properties were obtained. Morphostructural properties of cellulose microfibrils and polymer composites with treated and untreated microfibrils were investigated using scanning electronic microscopy (SEM), FTIR spectroscopy, and differential scanning calorimetry (DSC).

In this paper, an innovative method that uses hypericin "phyto-template" molecules is being applied herein for the first time to produce molecularly imprinted polymer (MIP) pearls able to selectively retain hypericin from Hypericum Perforatum L primary extracts. For this purpose, the wet phase inversion method was preferred for preparing the hypericin-MIP pearls for several reasons referring to economical benefits but also due to the fact that hypericin "phyto-template" molecules can be generated along with the phase inversion of the copolymer. Practically, the precursor poly(acrylonitrile-co-methacrylic acid) solution was mixed with a purified and concentrated naphtodianthrone phyto-extract (consisting only of hypericin and pseudo-hypericin). In the subsequent phase inversion step hypericin was trapped in the copolymer droplets, as a result to its poor solubility in the inversion water bath, and further served as "phyto-template" in the imprinting step. This in situ repartition of hypericin and pseudo-hypericin was sustained by HPLC-DAD chromatograms which recorded only the presence of hypericin during the extraction stage of imprinted pearls. Batch rebinding measurements, all together, validated the efficiency of this innovative imprinting procedure. The hypericin rebinding of imprinted pearls was quantitative (up to 318 µg/L) and approximately 5 times more specific relative to the blank pearls. Competitive re-binding revealed a more selective behaviour of imprinted pearls for hypericin when the up-take was measured against pseudohypericin (selectivity coefficient above 4.50).

The main goal of this study was to explore the suitability and performance of bicomponent polymer membranes based on acrylonitrile copolymers-polyvinyl alcohol (PVA) mixtures and small quantities of anion (Purolite A100) or cation exchange resin (Purolite C150), prepared by phase inversion. Membranes were used for copper removal from synthetic wastewater solutions. A three detachable cylindrical compartment electrodialysis cell without recirculation of the electrolytes and synthetic solutions of various concentrations, similar to a copper electrowinning electrolyte, were used. The electrodialysis unit operates under galvanostatic control. The effect of pH on electrodialysis separation of Cu2+ and on the solution conductivity has been also investigated. The laboratory electrodialysis cell performance was evaluated in terms of percent of extraction (pe) and current efficiency (ce). Experimental results showed that the ionic transfer in electrodialysis cell was especially affected by concentration. The highest values for the pe (>81 %) and the ce (>25 %) of copper ions were obtained at maximum concentration in copper ions (3 g/L), indicating a better performance of the ion extraction. The transport of copper ions was also correlated with flux data. The ion exchange membranes were characterized using FT-IR spectroscopy, ESEM, and electrochemical impedance spectroscopy.

Free radical miniemulsion polymerization of styrene (St), St/acrylonitrile 3 : 1 mixture or methylmethacrylate in the presence of multiwalled carbon nanotubes (MWCNT) was proven as a convenient way to obtain homogenous hybrids with perspectives in associated applications like foams specialties materials. Miniemulsion polymerization was viable up to 2% wt. MWCNT to monomer, without agglomerations. The grafting on MWCNT during the polymerization occurs without the need for supplementary functionalization and the polymer grafted nanotubes showed stable dispersions in the polymer solvent. Monomer polarity affected the grafting ability during the polymerization process. The nanocomposites obtained after purification and drying were used in foaming process. MWCNT presence in the related nanocomposites decreased the pore sizes in foam-like materials (for all three different matrices). At 1 wt % MWCNT content, low density ( 109 cell/cm3) were achieved. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41148.

Noncovalent entities (consisting of liposomes, phyto-nanosilver and carbon nanotubes) with interesting properties were constructed by a “green” bottom-up method. Phytosynthesis of silver nanoparticles using the Mentha piperita extract combines the benefits of this herb with the interesting properties of silver. The obtained silver-based biohybrids showed antioxidant and antimicrobial properties that have been considerable improved in the presence of carbon nanotubes. Thus the eco-designed bioconstructs consisting of cholesterol-containing liposomes , phytonanosilver and carbon nanotubes exhibited high antioxidant activity (AA = 90.8%) and have been shown to be strong biocides offering inhibition zone of 25 mm against Escherichia coli and 23 mm against Staphylococcus aureus and Enterococcus faecalis .

Polypropylene-based composites containing 10–30% by weight cellulose microfibrils were studied. Composites with polypropylene and cellulose microfibrils were characterised by MS-coupled simultaneous TGA-DSC and the reinforcing effect of cellulose microfibrils was emphasised by mechanical characterization. Experimental results are discussed in connection with the composite preparation method by mixing and extrusion. The effect of cellulose on the thermal stability and degradation behaviour of the polypropylene matrix is pointed out.

It is well-known that hydroxyapatite have multiple applications in tissue engineering due to compositional similarities with bone tissue. In this work, hydroxyapatite powders obtained by modified chemical precipitation route, has been investigated by AMF and SEM analysis grain size, X-ray diffraction and infra-red spectroscopy. The particle size of hydroxyapatite was observed to be very fine, uniform, around 50 -60 nm. SEM observation of the HA coatings showed the presence of nano-sized needles, with a significant level of agglomeration. The infrared analysis show the characteristic peaks of absorbed water, hydroxyl, phosphate and carbonate species. The XRD pattern clearly indicated the crystallites responsible for the Bragg reflection of the (002) and (003) planes are useful for size determination by Sherrer relationship (around 68 nm).

In the last decade, on the world wide it has been started to be applied the conservation of cultural heritage with nanomaterials. A deep investigation about the degradation mechanism of cultural heritage means the decisive step in the historical paper conservation. In particular, by using these compatible methods, it is possible to perform interventions without modification of the physicochemical and mechanical behavior of the materials, ensuring long-lasting effects. In this study alkaline nano-sized particles have been synthesized, as non-aqueous dispersions, because of their efficiency for the preservation of cellulose-based materials. The particles size and theirs size distribution have been measured by Dynamic Light Scattering (DLS) technique. The historical papers have been treated with the obtained nanoparticles and then the initial and treated book papers have been examined by Scanning Electron Microscopy (SEM).

The synthesis, characterization and application of biologically synthesized nanomaterials have become an important branch of nanotechnology. A wide range of nanophasic and nanostructured particles are being fabricated globally with the aim of developing clean, nontoxic and eco-friendly technologies. In this paper, we report the synthesis of highly dispersed nanoparticles using a marine plant (Mayaca fluviatilis) extract as the reducing agent. Silver nanoparticles was investigated employing UV/Visible spectrophotometry, SEM (Scanning Electron Microscopy) and TGA (Thermal Analysis). Mayaca fluviatilis was found to exhibit strong potential for rapid reduction of silver ions. It was observed that there is no correlation always between the colour development and the increase in absorbance exhibited by the nanometal synthesised. The work adds to the confirmation of previous reports on biosynthesis of nanometals using a marine plant.

We obtained a new system containing nematic liquid crystal doped with nanostructured copolymer-clay particles. The clay (Cloisite-type) was modified by copolymerization of maleic anhydride and divinyl benzene and the nanocomposite has intercalated structure. Current-voltage characteristics of the liquid crystal/copolymer-clay systems were analyzed and the electro-optical response at heating –cooling cycles for different applied electric fields is discussed. Dielectric spectroscopy measurements in the low frequency domain have shown different regimes of its temperature dependence as function of the sample nature and the applied voltage. Comparison is made with the bulk liquid crystal. Changes of the phase transition temperature are thus revealed.