Polythiophenes and oligothiophenes in zeolite hosts

The polymerization of different thiophenes in the channels of molecular sieve zeolite hosts is described. Thiophene, 3-methyIthiophene, 2,2'-bithiophene, and terthiophene were introduced into dehydrated proton-, Cu(II)- or Fe(III)-containing zeolites (NaY and Na-mordenite) from organic solvents or vapor-phase. In the large-pore hosts, green-black products are formed from the monomers within several minutes. Spectroscopic characterization (IR, UV-NIR) confirms the formation of oxidized polymer chains in the zeolite channels. UV-Near IR reflectance spectra of the zeolite/polythiophene samples exhibit a broad absorption from 500 to about 2500 nm as the bulk and not the resolved spectra of short oligomers, thus fairly long polymer chains are formed in the zeolites. Conducting polymers can be recovered after dissolution of the zeolite host in HF. 2, 2'-bithiophene and a-terthiophene in acidic H2Y and U^Y zeolites (2 and 6 protons per super cage/ß-cage) yield yellow-green and purple products, respectively. UV-NIR reflectance data indicate that the acidic zeolite hosts oxidize the thiophene oligomers to yield stable radical cations and dications in their channel systems

Patenting activity in manufacturing organoclays for nanocomposite applications

peer reviewedFor the last two decades, intensive research has been focused on developing reinforced polymers with incorporation of nanometric fillers. Amongst the different types of nanofillers, those based on layered silicates (commonly known as clays), have been most widely investigated. Dispersing clay sheets on a nanoscopic scale (so-called exfoliation) indeed allows materials with enhanced thermal, mechanical, rheological, flame retardancy and barrier properties to be produced. However, the nanocomposite performances are strongly dependent upon the extent of clay exfoliation. In order to enhance the compatibility between the pristine clay, hydrophilic, and the polymer, hydrophobic, and to achieve a good delamination of the nanolayers, an organo-modification of the clay is most usually necessary. This mini-review will provide an outline of patenting activity in the field of manufacturing organoclays through ionic exchange. The variety of organic modifiers and the diverse processing techniques will be detailed, aiming to extract the most relevant organoclays for successful nanocomposite formation at industrial scale

Polyester layered silicate nanohybrids by controlled grafting polymerization

peer reviewedPoly( epsilon-caprolactone) (PCL) layered silicate nanohybrids were synthesized by ring opening polymerization of epsilon-caprolactone according to a well-controlled coordination-insertion mechanism. Montmorillonites were surface-modified by non functional (trimethylhexadecylammonium) and hydroxy functional alkylammonium cations, i.e., (2-hydroxyethyl) dimethylhexadecylammonium. The hydroxy functions available at the clay surface were activated into tin( II or IV) or Al(III) alkoxide initiators for lactone polymerization, thus yielding surface-grafted PCL chains. The surface-grafted PCL chains were recovered by an ionic exchange reaction with lithium chloride and they were analyzed by size exclusion chromatography. The PCL molar mass was measured as a function of the hydroxy content of the clay that was modulated by exchanging the Na cations with mixtures of non-functional and hydroxy functional ammonium cations of different compositions. Nanohybrids were also characterized by small-angle X-ray diffraction, transmission electron microscopy and thermogravimetry. The PCL molar mass and the nanocomposite morphology (i.e., exfoliation and/or intercalation) were readily tuned by the content of the hydroxy groups available at the clay surface. Surface-grafted aluminium trialkoxide species proved highly efficient in initiating polymerization that leads to PCL chains of controlled molar mass and narrow molecular weight distribution with polydispersity indices as low as 1.2

Syntéza a charakterizace práškových nanokompozitů typu polypyrrol/fylosilikát

Import 02/11/2016This work is focused on the preparation and characterization of powder nanocomposites of polypyrrole/phyllosilicate type. Conducting nanocomposites were prepared by one–step method in which simultaneously intercalation and polymerization of pyrrole in the presence of montmorillonite using two different oxidants – ferric chloride and ammonium peroxydisulfate – took place. Prepared nanocomposites were analysed using scanning electron microscopy, X–ray diffraction, infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. With molecular modeling was created a series of models that were optimized and compared with the results of thermogravimetric analysis and X–ray diffraction analysis. By evaluation of prepared models were obtained possible internal arrangements of prepared nanocomposites of polypyrrole/montmorillonite type.Tato práce je zaměřena na přípravu a charakterizaci práškových nanokompozitů typu polypyrrol/fylosilikát. Vodivé nanokompozity byly připraveny jednokrokovou metodou, při které současně proběhla interkalace a polymerace pyrrolu v přítomnosti montmorillonitu s využitím dvou různých oxidačních činidel – chloridu železitého a peroxodisíranu amonného. Připravené nanokompozity byly analyzovány pomocí skenovací elektronové mikroskopie, rentgenové difrakční analýzy, infračervené spektroskopie, Ramanovy spektroskopie a termogravimetrické analýzy. Pomocí molekulárního modelování byla vytvořena série modelů, které byly optimalizovány a porovnány s výsledky z termogravimetrické analýzy a rentgenové difrakční analýzy. Vyhodnocením připravených modelů bylo získáno možné vnitřní uspořádání připravených nanokompozitů polypyrrol/montmorillonit.9360 - Centrum nanotechnologiívýborn

Staining of RNA and DNA on electrophoretic gels and in cytology with juice of Vaccinium myrtillus berries

Article id e02666.201

Polymer/montmorillonite nanocomposites with improved thermal properties: Part II. Thermal stability of montmorillonite nanocomposites based on different polymeric matrixes.

In previous part of this work factors influencing the thermal stability of polymer nanocomposite materials were indicated, such as chemical constitution of organic modifier, filler content, nanocomposites’ structure and the processing- dependent degree of homogenization of nanofiller, were presented. In this part the basic changes in thermal behaviour of different polymeric matrixes (e.g. polyolefins, polyamides, poly(vinyl chloride) and styrene-containing polymers) upon addition of montmorillonite have been described. Brief description of the kinetics of the decomposition process in inert and oxidative environment, as well as analysis of volatile and condensed products of degradation, have also been present

Designing organometallic compounds for catalysis and therapy

Bioorganometallic chemistry is a rapidly developing area of research. In recent years organometallic compounds have provided a rich platform for the design of effective catalysts, e.g. for olefin metathesis and transfer hydrogenation. Electronic and steric effects are used to control both the thermodynamics and kinetics of ligand substitution and redox reactions of metal ions, especially Ru II. Can similar features be incorporated into the design of targeted organometallic drugs? Such complexes offer potential for novel mechanisms of drug action through incorporation of outer-sphere recognition of targets and controlled activation features based on ligand substitution as well as metal- and ligand-based redox processes. We focus here on η 6-arene, η 5-cyclopentadienyl sandwich and half-sandwich complexes of Fe II, Ru II, Os II and Ir III with promising activity towards cancer, malaria, and other conditions. © 2012 The Royal Society of Chemistry

Polyfuran Conducting Polymers: Synthesis, Properties, and Applications.

In this review, polyfuran (PFu) synthesis methods and the nucleation mechanism; the electrochemical, structural, morphological, and magnetic properties of PFu; thermal behavior; theoretical calculations on PFu, as well as its applications reported to date, have been compiled. Not only PFu homopolymers have been reviewed, but also PFu co-polymers, PFu bipolymers, and PFu composites. The results are listed, discussed, and compared. It is hoped that this assembly of all the relevant data might enhance knowledge about this conducting polymer and lead to new research fields