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The present paper studies the effect of polyaniline grafting on magnetite functionalized with aminopropyltrimethoxysilane. All the compounds were characterized by analytical techniques (X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy, thermal analysis, Transmission electron microscopy), as well as by determining their magnetic properties. The electron microscopy analysis of the hybrids shows similar morphologies for all the samples. The presence of the iron atoms on the surface of the final product supports the idea of the existence of an inverted core-shell type structure, the more polar ferrite orienting itself towards water. The correlation between the maximum grafting probability and the maximum magnetization is evidenced, demonstrating the importance of the polymer grafting method on the magnetic properties.

Sol-gel derived organic-inorganic hybrid systems were obtained by applying alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), isobutyltriethoxysilane (IBTES), diethoxydimethylsilane (DMDES), and vinyltriethoxysilane (VTES), respectively, into a polymer latex functionalized with vinyltriethoxysilane (VTES). The properties of the latex hybrid materials were analyzed by FTIR, water contact angle, environmental scanning electron microscopy (ESEM), TEM and AFM analysis, respectively. FT-IR spectra confirmed that the chemical structures of the sol-gel derived organic-inorganic materials are changed as function of inorganic precursor and Si O Si networks are formed during the co-hydrolysis and copolycondensation reactions. The water contact angle on the sol-gel latex film containing TEOS + VTES increased to 135° ± 2 compared to 65° ± 5 for the blank latex, due VTES incorporation into latex material. TGA curves of hybrid sample modifies against neat polymer, the thermal stability being influenced by the presence of the inorganic partner. ESEM analysis showed that the latex hybrid films prepared with different inorganic precursors were formed and the Si-based polymers were distributed on the surface of the dried sol-gel hybrid films. TEM and AFM photos revealed that the latex emulsion morphology was modified due to the VTES incorporation into system.

Monolayer and bilayer coatings deposited on polypropylene (PP) surface were prepared by sol–gel process at room temperature. Monolayer coatings were produced from sol–gel acidic solutions, containing tetraethylorthosilicate (TEOS) and different co-precursors such as phenyltriethoxysilane (PhTES), octylmethyldimethoxysilane (OMDMS) and dodecyltriethoxysilane (DOTES). Bilayer coatings consist of one layer prepared in a similar way described for monolayer coatings, followed by a second layer, obtained from fluorinated silica nanoparticles dispersion. The fluorinated group has been confirmed by the presence of C F bonds along with network Si O Si vibrational mode. Water contact angle values registered for bilayer-coated polypropylene are higher, comparing with the reference (pristine PP) and with the monolayer-coated substrate, and varies as a function of the hydrophobic functional groups of the silica co-precursors: phenyl

Several fluorescent materials were prepared by embedding 3-methoxy-7H-benzo[de]anthracen-7-one in transparent sol–gel silica hybrids, in acid catalysis and at room temperature. The photophysical properties of the materials are studied in relationship with the structure and based on interactions established between the fluorophore, which display high sensitivity to minor changes in the local environments, and hybrid silica networks. Colored materials show marked differences in absorption and fluorescence spectra due to the environments around the dyestuff molecules created in the host matrices by grafting different organic moieties onto silica surface. The fluorescence emission spectrum of the obtained materials reveals a positive solvatochromism due to the intramolecular charge transfer character of the excited states and changes in the fluorophore dipole moment. Variations recorded in the fluorescence parameters of the hybrid materials confirm that some interactions are established between the fluorescent dyestuff and hybrid silica network.

The radical polymerization of aniline hydrochloride (ANIHCl) in the presence of ammonium persulfate was studied. 1D-Polyaniline (PANI) with fibrillar morphologies was obtained in the presence of anionic surfactants. The changes of the PANI-template structures in aqueous solution were studied using static fluorescence measurements. The dispersed PANI nanoparticles were characterized using dynamic light scattering, scanning electron microscopy (SEM), and Raman and Fourier transform infrared spectroscopies. The thermal analysis and the electrical conductivity of the dried samples were also performed. The fluorescence measurements indicated that nanocrystals of ANIHCl form in water complexes with the anionic surfactants at smaller concentrations than the critical micellar concentration. The same method revealed that other organic complexes with sulfonate groups do not induce an increase of the hydrophobic region due to short hydrocarbon tails. The SEM micrographs and Raman spectra revealed that the PANI nanofibers are compact and different compared to the nanoparticles prepared without surfactants.

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.

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.

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.

Ultra-hydrophobic bilayer coatings on a glass surface were fabricated by sol–gel process using hexadecyltrimethoxysilane (C16TMS) and tetramethoxysilane (TMOS) (1:4 molar ratio) as precursors. After coating, silica nanoparticles (SiO2 NPs) functionalized with different mono-alkoxy derivatives (methoxytrimethylsilane, TMeMS; ethoxydimethylvinylsilane, DMeVES; ethoxydimethylphenylsilane, DMePhES; and methoxydimethyloctylsilane, DMeC8MS) were added, assuring the microscale roughness on the glass surface. Influences of the functionalized SiO2 NPs and surface morphology on the hydrophobicity of the hybrid films were discussed. The successful functionalization of SiO2 NPs with hydrophobic alkyl groups were confirmed by Fourier transform infrared spectroscopy (FTIR). The thermal stability of hydrophobic SiO2 NPs showed that the degradation of the alkyl groups takes place in the 200–400 °C range. Bilayer coating with C16TMS/TMOS and SiO2 NPs modified with alkoxysilane substituted with C8 alkyl chain (SiO2 NP-C8) has micro/nano structure. Hydrophobicity of functionalized SiO2 NPs-C8 and its higher degree of nanometer-scale roughness gave rise to ultra-hydrophobicity performance for bilayer coating C16TMS/TMOS + SiO2 NPs-C8 (145°), compared to other similar hybrid structures. Our synthesis method for the functionalization of SiO2 NPs is useful for the modification of surface polarity and roughness.

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 describes a method to prepare silica particles able to encapsulate 3 different hydrophobic dyes: Disperse Red, Solvent Red and 2-{4-[4-(Benzyl-ethyl-amino)-phenylazo]-benzenesulfonyl}-ethanol (HESA). Dye doped silica particles were prepared by the sol–gel process in aqueous medium, with a base catalyst, using various concentrations of a “home made” surfactant (named NP9-Si). The surfactant is the addition byproduct of –OH groups of polyethylene glycol nonylphenyl ether Tergitol® NP-9 with -NCO groups from (3-isocyanatopropyl) triethoxysilane and was added to increase both the stabilization of the silica particles and the compatibility of the inorganic network versus the dopant (the aromatic dye). It was shown that there is an optimum range of the amount of surfactant which should be added in the sol–gel reaction system. If a higher amount of surfactant is used, it forms probably micelles which entrap the dye and prevent its encapsulation in the formed silica particles. Because the silica particles are designed to encapsulate systems containing aromatic derivatives (aromatic dyes) we used phenyltriethoxy silane and tetraethylorthosilicate as silica precursors. As coupling agent for the silica network we used a bis (trialkoxysilane) derivative—1,2-bis (triethoxy silyl) ethane.

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.

Cellulose nanofibers were obtained from microcrystalline cellulose (MCC) by the action of hydrodynamic forces associated with ultrasound. Nanofibers isolated from MCC by applying different ultrasonication conditions were characterized to elucidate their morpho-structural features by field emission scanning electron microscopy, atomic force microscopy, X-ray diffraction, and dynamic light scattering. Several differences were observed regarding the size of the nanofibers obtained in different ultrasonic conditions, but no significant changes in the crystalline structure of cellulose nanofibers were detected. The obtained cellulose fibers were used at low levels (1 to 5 wt.%) as reinforcements in a poly(vinyl alcohol) (PVA) matrix. The mechanical and thermal properties of the PVA/cellulose fibers nanocomposites films were determined. The tensile strength and modulus of the PVA film were significantly improved by the addition of cellulose nanofibers. Slightly higher onset degradation temperatures were obtained for PVA composites in comparison to neat PVA, showing an increase of the thermal stability caused by the addition of cellulose fibers.

Heterogeneous membranes were obtained by using styrene-acrylonitrile copolymer (SAN) blends with low content of ion-exchanger particles (5 wt.%). The membranes obtained by phase inversion were used for the removal of copper ions from synthetic wastewater solutions by electrodialytic separation. The electrodialysis was conducted in a three cell unit, without electrolyte recirculation. The process, under potentiostatic or galvanostatic control, was followed by pH and conductivity measurements in the solution. The electrodialytic performance, evaluated in terms of extraction removal degree (rd) of copper ions, was better under potentiostatic control then by the galvanostatic one and the highest (over 70%) was attained at 8 V. The membrane efficiency at small ion-exchanger load was explained by the migration of resin particles toward the pores surface during the phase inversion. The prepared membranes were characterized by various techniques i.e. optical microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis and differential thermal analysis and contact angle measurements.

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.

Polyacrylonitrile (PAN) and poly(acrylonitrile-co-vinylcarbazole) (PAN-VK) hybrids were obtained in presence of multiwalled carbon nanotubes (MWCNT) by a one-step free radical polymerization in miniemulsions. MWCNTs, in an unmodified state, as well as MWCNTs functionalized with maleic anhydride or monoethoxy dimethylvinyl silane, were used. The presence of MWCNT increased the molecular weights of the polymers and affected the polydispersity index. The polymers obtained next to the MWCNT showed a high value in their crystallinity index (33 %). The method was proven as an efficient route for dispersing nanotubes in the polymer matrix. Functionalized MWCNTs restrict the transfer reaction to areas next to the walls of the nanotubes during the polymerization and increase the dispersability in the final polymer matrix. MWCNT –polymer hybrids showed perspectives in membrane fabrication, as well as a specific profile, for carbon fibers precursors (with advantages in the three main stages: cyclization, dehydrogenation and decomposition).

The present study describes for the first time the synthesis of silica nanoparticles starting from sodium silicate and oleic acid (OLA). The interactions between OLA and sodium silicate require an optimal OLA/OLANa molar ratio able to generate vesicles that can stabilize silica particles obtained by the sol-gel process of sodium silicate. The optimal molar ratio of OLA/OLANa can be ensured by a proper selection of OLA and respectively of sodium silicate concentration. The titration of sodium silicate with OLA revealed a stabilization phenomenon of silica/OLA vesicles and the dependence between their average size and reagent’s molar ratio. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements emphasized the successful synthesis of silica nanoparticles starting from renewable materials, in mild condition of green chemistry. By grafting octadecyltrimethoxysilane on the initial silica particles, an increased interaction between silica particles and the OLA/OLANa complex was achieved. This interaction between the oleyl and octadecyl chains resulted in the formation of stable gel-like aqueous systems. Subsequently, olive oil and an oleophylic red dye were solubilized in these stable aqueous systems. This great dispersing capacity of oleosoluble compounds opens new perspectives for future green chemistry applications. After the removal of water and of the organic chains by thermal treatment, mesoporous silica was obtained.

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.