Syndiotactic-atactic stereoblock polystyrene obtained with a hapto-flexible catalyst

Half-titanocene (CpCH2CH2OCH3)TiCl 3 (1), (Cp = cyclopentadienyl), activated by methylaluminoxane (MAO), has been tested in the polymerization of styrene in a suitable range of temperatures, obtaining a new material consisting of syndiotactic-atactic stereoblocks of polystyrene. The monoanionic bidentate ancillary ligand of the titanium based catalyst, consisting of a cyclopentadienyl bearing an alkyl ether, is a hapto-flexible ligand because the ether group can either be coordinated or not to the metal, depending on reaction temperature. Thus, the ether group can give rise to two possible catalytic sites: (i) syndiospecific, when the ether group is not coordinated to the metal center, and (ii) aspecific, when it is coordinated to titanium. Consequently, it produces polymer chains having syndiotactic and atactic stereoblocks. In fact, in the range of temperature considered (0-19 °C), syndiotactic polystyrene was produced at 19 °C, atactic polystyrene at 0 and 5 °C, and syndiotactic-atactic stereoblock polystyrene at 10 and 15 °C

New Application of Oxidized Nanocarbons: from Catalysis to Nanocomposites”

Oxidized Nanocarbons, mainly regarding Graphite Oxide (GO) and Oxidized Carbon Black (oCB) are 2D carbon nanostructures containing many hydrophilic groups, making them promising in many potential applications. In particular, GO and oCB has recently been used both as catalyst for important organic reactions (1-4) and as filler of polymers (5-7). The first part of the contributes will describe preparation and use of oxidized nanocarbons, their ability to catalyze some important reactions and how this catalytic activity can be technologically relevant for polymeric matrices, mainly regarding epoxide and phenolic resins. The second part of the contribution will be devoted to the incorporation of carbon nanofillers in several commercial biodegradable polyesters. In particular in this study we will show that the incorporation of oxidized nanocarbons induce polymer degradation during melt processing. On the contrary, their covalent functionalization minimizes polymer degradation in melt processing, thus allowing the production of polyesters/graphite-based nanocomposites. Furthermore, a nucleation effect was observed able to increase the crystallization kinetic ten times more than the usual filler. We carried out functionalization of GO (fG) and oCB (fG) by introduction of alkyl groups by a wellknown methodology (8) and acetyl groups by a new green procedure (9).With both functionalizations, improved melt stability and faster crystallization kinetic were achieve

Green and Facile Esterification Procedure Leading to Crystalline-Functionalized Graphite Oxide

A simple and eco-friendly procedure of esterification of graphite oxide (GO), which uses acetic anhydride as a model reagent and ethyl acetate as a green solvent, is reported. The procedure leads to high functionalization degrees (at least up to 4.5 mol % of acetyl groups, referred to as graphitic C atoms) and it is much more effective than the literature method based on pure acetic anhydride. Surprisingly, our acetylation procedure does not destroy or reduce GO crystallinity but, irrespective of a substantial increase of distance between GO layers (from 0.84 nm up to 0.95 nm), leads to an increased order in the direction perpendicular to the graphitic planes. This phenomenon indicates that acetyl groups of acetylated GO (AcGO) are easily accommodated between graphitic layers, even improving interlayer order. The esterification procedure is generally applicable with various anhydrides providing differently functionalized graphite oxide. Dispersion of crystalline functionalized GO in volatile organic solvents followed by solvent fast removal, can easily lead to complete exfoliation

Annurca (Malus pumila Miller cv. Annurca) apple as a functional food for the contribution to a healthy balance of plasma cholesterol levels: results of a randomized clinical trial

Recent human studies have evaluated the effect of daily apple consumption on plasma cholesterol level, which is recognized as an important risk factor for cardiovascular disease (CVD). Nevertheless, slightly significant effects have been generally registered although consuming more than two apples a day for several weeks

Insecta Hemiptera collected in the Mont Avic Natural Park (Aosta Valley, Northwest Italy)

The results are given of the Hemiptera collection exscursions in the Monte Avic Natural Park (Aosta Valley, NW Italy) that took place during the 4th European Hemiptera Congress held in Ivrea in September 2007. Altogether 126 species of Heteroptera, belonging to 89 genera, 108 species of Auchenorrhyncha, belonging to 75 genera, and 30 species of Sternorrhyncha Psyllomorpha, belonging to 8 genera were collected at the four different elevation sites of Capoluogo-Tendeur (500-600m a.s.l.), Chevrère (1200-1400m a.s.l.), Dondena (2100-2300m a.s.l.), and Miserin (2588m a.s.l.). Of these species, 2 were new records for Italy: the Mirid Lygus maritimus and Cicadellid Edwardsiana ishidai. New records for Italy are also the Pipunculid Dipteran Tomosvarjella freidbergi and the Halictophagid Strepsipteran Halictophagus languedoci, parasitoids of Auchenorrhyncha