Band 88, Heft 10-11

The versatile reactivity of hexachlorocyclotriphosphazene (N 3 P 3 Cl 6 ) has been developed for the synthesis of specifically engineered dendrimers. Dendrimers are hyperbranched macromolecules built by concentric layers constituted of associated monomeric units. Many of the properties of dendrimers depend on the type of their surface (terminal) functions, which are generally all identical. For some specific purposes, it is desirable to have one function that is different at the level of the core. Hexachlorocyclotriphosphazene offers the possibility to differentiate the reactivity of one (or more) Cl from the others, for producing specifically engineered dendritic tools. These specific reactions on N 3 P 3 Cl 6 have produced highly dense dendrimers, Janus dendrimers (two faces), tools for functionalizing materials, with uses as catalysts, as chemical sensors, for trapping CO 2 , for the culture of cells, or for imaging biological events. These properties will be emphasized in this review.

Our recent results in the field of microwave (MW)-assisted organophosphorus syntheses, especially regarding esterifications, condensations, substitutions and additions are surveyed. Beside making organic chemical reactions more efficient, it was possible to perform transformations that are reluctant on conventional heating. Another option is to substitute catalysts, or to simplify catalyst systems under MW conditions. It is also the purpose of this paper to elucidate the scope and limitations of the MW tool, to interpret the MW effects, and to model the distribution of the local overheatings and their beneficial effect. All these considerations are possible on the basis of the enthalpy of activations determined by us utilizing the Arrhenius equation and the pseudo first order kinetic equation.

Polyphosphoesters are environmentally friendly and multifunctional materials. They were noted for their special properties, i.e. fire resistance, plasticity, lubricity, high physical-mechanical performance, thermal stability, and as degradable biopolymers which properties can be modified specifically to desired application in medicine, biology and agriculture. They have a wide range of application as: flame retardants, scaffolds for tissue engineering, gene carriers, drug delivery, carriers for the sustained release of nerve growth factor, pH/thermoresponsive materials, or as solid polymer electrolytes. In this paper we present our researches concerning the synthesis and application of polyphosphates, and polyphosphonates using different modern methods. Different approaches were used. These polyphosphoesters were used as solid polymer electrolytes for lithium polymer batteries by complexation of polyphosphoesters obtained from different phospho(n)ric dichlorides and aliphatic or aromatic diols with lithium salts. These polymers present two important features: they have good conductivity, around 10 −6 S/cm, and are fire proof.

The use of polyisobutylene and poly(4-dodecylstyrene) bound catalysts that contain transition metal or organocatalysts for cyclopropanation, ring-closing metathesis, and nucleophilic catalysis in flow chemistry schemes is described and compared with similar catalysts used in batch reactions. These Rh(II) carboxylate catalysts, N -heterocyclic carbene-ligated Ru(II) benzylidene catalysts, and analogs of 4-dimethylaminopyridine catalysts were used in reactions in heptane in flow and then separated in a gravity based liquid/liquid separation using a biphasic heptane/acetonitrile mixture. The less dense catalyst-containing phase in that separation was continuously used in flow with fresh substrate solution. Leaching of catalysts, yields, and turnover frequencies in these flow reactions were comparable with prior results obtained with the same phase isolable catalysts in batch reactions.

Calcium carbonate (CaCO 3 ) was synthesized by means of ultrasonic process in the presence of the water-soluble polymer carboxymethyl inulin (CMI). Synthesized CaCO 3 crystals were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET (Brunauer, Emmett and Teller) isotherm. Applying Box-Behnken experimental design, the effects of the amplitude of sonicator (Amp), biopolymer concentration (BC) and the application time of ultrasound (AT) on the preparation of CaCO 3 with respect to specific surface area (SSA) of final product was investigated. The experimental design was studied at three levels. The range of the amplitude of sonicator, polymer concentration and the application time of ultrasound were 25%–50%, 0.25–0.75 g/L and 1–5 min, respectively. The model equation representing specific surface area (SSA) of calcium carbonate was expressed as functions of three operating parameters namely the application time of the ultrasound, the amplitude of sonicator and polymer concentration. The results showed that the application time of ultrasound was the most significant variable that influenced the surface area of the crystals among three variables and the experimental results were in good agreement with those predicted by the proposed regression model. The highest value of specific surface area was obtained at the maximum application time of ultrasound.

The development of new materials for the consolidation of waterlogged archaeological wood from sustainable sources is an important area of research, as the most widely used consolidant today is petroleum based. Ideally a new consolidant will interact with the existing wood structure, ensuring maximum compatibility. Lignin is often the major component remaining in archaeological wood, as it is less susceptible to degradation than holocellulose. Therefore, in order to maximise the potential for interaction with the wood cells, lignin-like oligomers have been synthesized from isoeugenol using a water soluble copper salen catalyst at pH 10, giving a weight average M w of 1.6 kDa. Analysis by NMR spectroscopy has shown that the oligomers have a lignin-like structure with β-O-4′, β-β′ and β-5′ connections. A 10 w/w% solution of the oligomers in ethyl acetate was found to thoroughly penetrate 1 cm 3 samples of waterlogged archaeological wood (density of 0.146 g/mL, maximum water content of 620%) after 14 days impregnation, as determined by FTIR spectroscopy. No impregnation material could be seen by SEM, suggesting that it coats the cell walls upon drying. This indicates that dehydrogenated polymers penetrate waterlogged archaeological wood well and have the potential to be developed into consolidants.

Due to the large amount of industrial activity during the last century, heavy metal contamination of the environment has become a serious problem. Therefore, it is important to develop new and efficient methods of heavy metals removal from aqueous solutions. In this respect, three phosphonate metal organic frameworks were obtained in our labs by the reaction of divalent inorganic salt (CoSO 4 ·7H 2 O), phosphonic acid [phosphonoacetic (CP), N,N-bis(phosphonomethyl)glycine (Gly) and vinylphosphonic (VP)] in hydrothermal conditions. The synthesized compounds were characterized by FTIR, X-Ray crystallography scanning electron microscopy and thermogravimetric analysis. These materials were used in the removal process of lead ions from aqueous solutions in order to determine the possibilities of their use as adsorbent materials. The effect of pH, lead initial concentrations and contact time upon the adsorption properties were investigated. From the experimental data it can be observed that the Co-Gly material developed a higher adsorption capacity for lead metal ions than the Co-VP and Co-CP, increasing following Co-CP<Co-VP<Co-Gly trend.

In the present work, we describe the synthesis and characterization of styrene-6.7%-divinylbenzene copolymers functionalized with aminophosphonate groups by “one-pot” reactions. Different aminophosphonate groups were grafted on the copolymer with the aim of obtaining adsorbents for removal of phenolic compounds from aqueous solutions. Adsorption experiments were carried out in batch system. The phenolic compounds studied were phenol and 2,4,6-trimethyl-phenol. The best adsorption capacity was observed in the case of polymeric adsorbents functionalized with aminophosphonate groups in para- position of the aromatic nucleus for both phenol and 2,4,6-trimethyl-phenol. In comparison, the copolymers with the functional groups in ortho- position and respectively in meta- position were slightly less efficient. The differences in adsorption efficiency may be explained taking into account the structure of the adsorption active centers. The possible explanation is that the active functional groups responsible for the adsorption process, grafted in ortho- or meta- position could be affected by possible steric hindrance effects. The difference between the adsorption capacities of the polymers of the same series, are rather small and depending on the nature of the radical found in the structure of the aminophosphonate: isopropylamine or isobuthylamine.

A series of new paraphenylene-based 2D and 3D tectons has been designed for supramolecular self-assembly on both HOPG and Au. Several versatile chemical strategies have been developed to reach the target tectons, bearing either metaparacyclophane or paraparacyclophane cores, functionalized or not, allowing the obtention soon of more complex 3D tectons bearing functional unit such as chromophores. Moreover, preliminary STM results show that these compounds can successfully self-assemble both on HOPG and Au(111) substrates at liquid-solid interface, encouraging us in finding an universal surface-confined 2D/3D molecular binding motif. This feature combined with the preliminary results of the self-assembly on the plasmonic substrate Au(111) open-up opportunities in the field of Nanoscience.

Zinc oxide (ZnO) particles were synthesized from aqueous solution by chemical precipitation method. Self-aggregated rod-shaped particles were obtained. Silane modification and ultrasonic dispersion were compared in terms of effectiveness on particle deagglomeration. Complete deagglomeration was achieved with ultrasonic dispersion for untreated particles. Surface-treated and/or ultrasound-applied ZnO particles were incorporated into PHBV matrix by melt-extrusion. Good particle dispersion was achieved in the composites regardless of the agglomeration observed in particles prior to polymer matrix inclusion. Number of regular, rod-shaped particles observed was higher in the composites produced with ultrasound-dispersed particles. ZnO crystals did not affect the melting and crystallization temperatures of PHBV composites, but the degree of crystallinity was decreased. Thermal degradation temperature of PHBV was slightly decreased with ZnO addition. Tensile strength, elongation at break, and toughness of PHBV were affected positively when ultrasound-dispersed (treated or untreated) particles were incorporated into PHBV matrix; whereas application of both ultrasound and silane treatment produced better results.

Silicic acid polycondensation leads to the formation of amorphous silica. This process is of great importance to the survival of certain living organisms, such as diatoms and sponges, but presents a significant problem in various production facilities that use water for heating or cooling. In the latter, amorphous silica can be a recalcitrant deposit that can hamper proper system operation. Hence, inhibition of silicic acid polycondensation by chemical inhibitors is an intensely sought strategy by water system operators. In this manuscript, we report the inhibitory effect of zwitterionic phosphonated analogs (PPEI’s) of the cationic polymeric chemical additive polyethyleneimine (PEI) in mildly supersaturated silica solutions (500 ppm/8.3 mM “Si”) at pH=7. The inhibition efficiency of PPEI’s depends on a variety of parameters, such as concentration and degree of phosphonomethylation of the parent PEI polymer.

Very high energies of particulate (accelerated electrons, swift heavy ions) or electromagnetic wave (γ-, X-rays) radiation can be used to initiate free radical based reactions in solids, liquids or gases. Because of non-selectivity of absorption of X-rays, γ rays and accelerated electrons in matter free radicals are generated homogeneously in the bulk material. These free radicals on the polymers or monomers are used extensively in the synthesis and modification of polymeric materials. The unique properties of ionizing radiation make it a very useful tool in the top-down and bottom-up synthesis of nanomaterials. In this article the utilization of ionizing radiation in the form of swift heavy ions, accelerated electrons, X- and γ rays will be described for development of advanced materials by radiation-induced grafting in nanoscale, synthesis of polymeric nanoparticles, radiation-assisted synthesis of nanogels and nanocomposites. The properties difficult to be attained by other techniques will be described by giving examples for the cases of ion track-etched membranes, fuel cell membranes, sensors, detectors, cell culture media, polymer thin films embedded with metal nanoparticles, polymer/clay nanocomposites with a prospect for the future outlook.

Results of thorough investigations of tautomerism in the ground and excited electronic states performed for various organic molecules under different regimes: condensed phases, isolated and single molecules, with a special emphasis on porphycene, a porphyrin isomer, demonstrate that, in order to precisely describe the proton/hydrogen transfer path, one has to explicitly consider tunneling. Tautomerization is a multidimensional process, controlled by excitation of specific vibrational modes. Vibrational excitation can both enhance or hinder the reaction. The role of specific vibrational modes can now be assessed, even at the level of single molecules.

IUPAC recommendations on source-based nomenclature for single-strand polymers have so far addressed its application mainly to copolymers, non-linear polymers and polymer assemblies, and within generic source-based nomenclature of polymers. In this document, rules are formulated for devising a satisfactory source-based name for a polymer, whether homopolymer or copolymer, which are as clear and rigorous as possible. Thus, the source-based system for naming polymers is presented in a totality that serves as a user-friendly alternative to the structure-based system of polymer nomenclature. In addition, because of their widespread and established use, recommendations for the use of traditional names of polymers are also elaborated.