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    Wyświetlanie 1-8 z 8
    Tytuł:
    Polimery z pamięcią kształtu i ich otrzymywanie
    Shape-memory polymers and their preparation
    Autorzy:
    Andrzejewski, Kewin
    Czyżów, Wiktor
    Jacewicz, Dagmara
    Drzeżdżon, Joanna
    Powiązania:
    https://bibliotekanauki.pl/articles/2086740.pdf
    Data publikacji:
    2022
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    polimery
    synteza
    katalizatory
    zielona chemia
    polymers
    synthesis
    catalysts
    green chemistry
    Opis:
    SMP (shape-memory polymers) is an innovative class of programmable materials responsive to various stimuli. They are attracting increasing attention regarding possible new inventions, industrial use, and overall polymer research. After a brief introduction, this article examines the conventional shape-memory effect, methods of fabrication of shape memory polymers, and molecular and structural requirements for SMP to function. The shape memory behavior of such polymers is thoroughly presented, with the focus being on the thermo- and photo-induced SME. The uses in biomedical and industrial areas are also discussed.
    Źródło:
    Wiadomości Chemiczne; 2022, 76, 3-4; 183--205
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zastosowanie spektroskopii w podczerwieni w adsorpcji i katalizie (I)
    Application of infrared spectroscopy in adsorption and catalysis (I)
    Autorzy:
    Sarbek, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/171796.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    spektroskopia IR
    chemisorpcja
    adsorbenty
    katalizatory
    IR spectroscopy
    chemisorption
    adsorbents
    catalysts
    Opis:
    The review presents some key results of infrared investigations of adsorbents and catalysts, which were obtained in Laboratory of Adsorption and Catalysis at Adam Mickiewicz University – conducted under the author guidance. After short introduction, review is divided into seven parts. In the first chapter, there was described an application of infrared method devoted to examination of structure of different types of zeolites, such as A, X, Y and mordenite as well as alumina and fly ashes and their modifications. Moreover, some results were presented on cobalt–molybdena catalysts supported on alumina. In the next chapter chemisorption of pyridine and t-butylnitrile (TBN) molecules on the alumina and alumina modified with fluoride and sodium ions as well as Co(Ni)-Mo(W) catalysts supported on alumina were investigated. In the last case intensity of some spectra were correlated with catalytic activity for cumene cracking. Another set of experiments were devoted to transesterification on dealuminated mordenites containing cations of alkaline earths elements and correlation with infrared results. In the next part of review, chemisorption of ethanol was presented. It was concluded, that during chemisorption of ethanol different surface species were produced on alumina, silicaalumina and zeolites X and ZSM-5. In separate chapter, it was considered oligomerization of different alkenes on Phillips catalyst using IR methods. In the last chapter, ways of chemisorption of dihydrobenzenes on cobalt-molybdena catalyst were examined using IR reflectance spectra. It seems that above presented results based on infrared examination will help to better understand adsorbents and catalysts structure and their action during adsorption and catalytic reactions.
    Źródło:
    Wiadomości Chemiczne; 2011, 65, 5-6; 363-394
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kompozyty uporządkowanych krzemionkowych materiałów mezoporowatych z rodziny M41S
    Composites of ordered silica mesoporous materials from the M41S family
    Autorzy:
    Zabłocka, I.
    Wysocka-Żołopa, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/172593.pdf
    Data publikacji:
    2018
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    uporządkowana mezoporowata krzemionka
    kompozyty
    katalizatory
    sorbenty
    polimery
    ordered mesoporous silica
    composites
    catalysts
    sorbents
    polymers
    Opis:
    Report on the discovery of a new group of ordered mesoporous M41S molecular sieves initiated the extensive use of these materials in scientific research. There were 3 different pores differing in the pore system, generally called MCM (Mobil Composition of Matter): MCM-41 with hexagonal structure, MCM-48 with regular structure and MCM-50 with lamellar structure (Fig. 1). The first proposed synthesis of materials from the M41S group is based on the use of organic surfactants as matrices [4]. The applied modifications of the synthesis method allowed, among others for easy and fairly accurate control of morphology, change of physical properties of the obtained silicas and have an impact on time, cost and simplicity of execution [12, 16, 23–34]. They concerned the use of additional organic and inorganic substances [23–25], changes in reaction conditions [12, 16, 26–29], as well as the use of innovative surfactants [30–34]. Due to its porous structure, the mesoporous silica creates opportunities to improve the properties of many materials, which is why many composites have been synthesized with its used in catalysing, sorption or improving the properties of polymers. Mesoporous titanium catalysts (Ti-MCM-41) were used in the catalysis of the redox reaction or as photocatalysts [44–71]. In addition to titanium, other transition metals have also been introduced into the MCM-41 network, including vanadium, zirconium, niobium, iron, ruthenium, silver, nickel, tungsten [43, 72–98] used as catalysts in organic reactions or as catalysts in the ozonation process [ 99–111]. Polymer composites belong to hybrid materials made of an organic polymer matrix dispersed in inorganic silica. Conductive polymers such as polyaniline and polypyrrole are often used in mesoporous polymer composites due to the ability to conduct electric current [117–133]. The main use of composites with mesoporous silica in sorption processes is to use them to remove impurities from water and gases. MCM-48 composites with various amines were used in the carbon dioxide adsorption process, and composites with niobium and nickel in deodorization processes [141–155]. Synthesis of composites with organic compounds allows to obtain good adsorbents of heavy metals such as: lead, cadmium, arsenic, copper, nickel, zinc and mercury [146–152].
    Źródło:
    Wiadomości Chemiczne; 2018, 72, 11-12; 841-865
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synteza i zastosowanie nowych katalizatorów metatezy olefin
    Synthesis and application of new olefin metathesis catalysts
    Autorzy:
    Hryniewicka, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/172521.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    metateza olefin
    katalizatory rutenowe
    pochodne chromanu
    sole imidazolidyniowe
    glikokoniugaty
    olefin metathesis
    ruthenium catalysts
    chromane derivatives
    imidazolinium salts
    glycoconjugates
    Opis:
    Olefin metathesis has emerged as a powerful tool for the formation of carboncarbon double bonds. The success of this methodology has spurred the intense investigation of new catalysts showing a better application profile. The syntheses and the application profiles of the seven new ruthenium metathesis catalysts have been described. Five of them were modified in benzylidene part with 6-hydroxychromane- and 2H-3,4-chromenemethylidene moiety. In chromanol – α-tocopherol model compound, some specific stereoelectronic effects have been observed. Introduction of this ligand to the catalyst may provide new advantageous properties. The other new catalysts contained modified N-heterocyclic carbene ligand (NHC), in which N,N’-mesityl substituents of NHC system were linked with diethylene glycol chain as a “clamping ring”. This ring would contribute to a steric shield of the NHC and ruthenium coordination center. Probably it may inforce a proper orientation of substituents in metallacyclobutane (all-cis), leading to Z-olefin formation. The obtained catalysts were investigated in model reactions: ring closing metathesis, cross metathesis and enyne metathesis. The experiments proved they efficiency. In many reactions the catalysts showed activity comparable or superior to that of commercially available Grubbs and Hoveyda 2nd generation complexes. Stereochemistry Z/E of the cross-metathesis products obtained using new and known complexes were similar as well. The catalysts were applied in the synthesis of a new type of α-tocopherol glycoconjugates. An efficient method of the synthesis Hoveyda 2nd type complexes starting from ruthenium trichloride was developed. It is possible to circumvent using special laboratory equipment and expensive reagents. Hoveyda type complexes can be achieved with very good yield in gram scale. Keywords:
    Źródło:
    Wiadomości Chemiczne; 2014, 68, 11-12; 961-980
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zastosowanie spektroskopii w podczerwieni w adsorpcji i katalizie (II)
    Application of infrared spectroscopy in adsorption and catalysis (II)
    Autorzy:
    Sarbak, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/171816.pdf
    Data publikacji:
    2011
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    spektroskopia IR
    tlenek węgla
    chemisorpcja
    powierzchnia katalizatorów
    depozyt węglowy
    katalizatory
    FTIR
    carbon monoxide
    chemisorption
    catalyst surface
    coke deposition
    catalysts
    Opis:
    The review presents important results on infrared examination of adsorbents and catalysts, which were obtained in Laboratory of Adsorption and Catalysis in Environmental Protection at Adam Mickiewicz University – conducted under the author guidance. In the first chapter results on chemisorption of carbon monoxide on Pt and Pt–Sn catalysts supported on various carriers such as alumina with different specific surface area and silica were described. For these catalysts different amount of Pt or Pt and Sn were used. Besides, catalysts obtained by different preparation procedures were also investigated. Second chapter contains description of coke deposit on alumina and silica supports as well as on Pt and Pt–Sn catalysts supported on above mentioned carriers. Special attention was also devoted to coke deposition on aluminosilicate, zeolite type A, X and ZSM-5 and Pt–Cr, Pt-Mo and Pt-W catalysts supported on alumina. Moreover, coke deposition on alumina contained chloride ions and molybdena- (VI) ions on alumina activated by reduction and sulfidation were also investigated. It seems that above presented results based on infrared examination will help to better understand of adsorbents and catalysts structure and their action during adsorption and catalytic reactions.
    Źródło:
    Wiadomości Chemiczne; 2011, 65, 5-6; 395-426
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Karbeny N-heterocykliczne : synteza i zastosowanie
    N-heterocyclic carbenes : synthesis and applications
    Autorzy:
    Malinowska, M.
    Hryniewicka, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/171528.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    karbeny N-heterocykliczne
    sole imidazolidyniowe
    katalizator metatezy
    organokataliza
    reakcja sprzęgania
    N-heterocyclic carbenes
    imidazolinium salts
    methatesis catalysts
    organocatalysis
    coupling reactions
    Opis:
    N-Heterocyclic carbenes (NHCs) are powerful tools in organic chemistry, with numerous applications in academic and industrial laboratories. They are usually defined as singlet carbenes, in which the divalent carbonic centre is connected directly to at least one nitrogen atom in the heterocycle [1]. They have played an important role in organic chemistry ever since the first evidence of their existence. The isolation of stable, free 1,3‑diadamantylimidazol-2-ylidene (IAd, Fig. 1) by Arduengo et al. in 1991 was a milestone in the chemistry of carbenes [2]. From the beginnings as academic curiosities, N‑heterocyclic carbenes today are very useful compounds in a variety of organic transformations (Fig. 13). NHCs are neutral σ-donors, which form very strong bonds with the majority of transition metals (stronger than phosphines). These compounds are easy-to-make ligands with great potential in homogeneous catalysis (mainly ruthenium and palladium complexes) for large number of reactions, including the coupling reactions (Heck, Negishi, Stille, Suzuki or Sonogashira reactions) and olefin metathesis [3]. Moreover, they are very useful as organocatalysts used in the benzoin condensation, the Stetter reaction and ring-opening polymerization (ROP) or transesterification [4]. In this review, we aim to give an overview of the properties and applications of NHCs, which we expect will be a useful introduction for chemists interested in studying and applying these important compounds. The first part of this review is devoted to the main synthetic routes to NHCs, their properties and reactivity. In the second part we describe the metal complexes with NHCs as homogeneous catalysts and their applications in various types of reactions. At the end of this part of the paper the use of NHCs as organocatalysts is presented.
    Źródło:
    Wiadomości Chemiczne; 2015, 69, 3-4; 227-253
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kataliza przeniesienia międzyfazowego jako nowoczesna technika w syntezie organicznej
    Phase-transfer catalysis as a modern technique in organic synthesis
    Autorzy:
    Siewniak, Agnieszka
    Chrobok, Anna
    Powiązania:
    https://bibliotekanauki.pl/articles/1853730.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    kataliza przeniesienia międzyfazowego
    czwartorzędowe sole amoniowe
    poli glikole etylenowe
    katalizatory chiralne przeniesienia międzyfazowego
    phase-transfer catalysis
    quaternary ammonium salts
    polyethylene glycols
    chiral phase-transfer catalysts
    Opis:
    Phase-transfer catalysis (PTC) has been already known for 60 years and has an established position both on a laboratory and industrial scale. It is an energy-saving technique, ensuring high yields and selectivity under mild conditions. PTC is successfully used, among others, in the pharmaceutical, polymer, agrochemical industries, for the production of dyes, fragrances and flavors, to name a few. Currently, the development of phase-transfer catalysis is focused mainly on the search for active catalysts as well as extending the scope of its applications. In particular, catalysts immobilized on an insoluble carrier, which can be easily separated from the reaction mixture and recycled many times, are of great interest. The growing demand for chiral compounds has resulted in the development of phase-transfer catalysts which, while retaining the advantages of conventional PTC, will allow to obtain a product with high enantiomeric excess. This work characterizes the phase-transfer catalysis and presents examples of its applications in organic synthesis.
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 9-10; 1297-1315
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gold catalysts supported on zeolites
    Katalizatory złotowe osadzone na zeolitach
    Autorzy:
    Walkowiak, Adrian
    Powiązania:
    https://bibliotekanauki.pl/articles/2057912.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    heterogeniczne katalizatory złotowe
    nanocząstki złota
    zeolity
    metody modyfikacji zeolitów złotem
    zastosowanie zeolitów modyfikowanych złotem
    proces katalityczny
    heterogeneous gold catalysts
    gold nanoparticles
    zeolites
    methods of zeolites modification with gold
    application of gold-modified zeolites
    catalytic process
    Opis:
    Heterogeneous gold catalysis is a relatively young but dynamically developing field of chemistry. At the end of the 1980s, Masatake Haruta and Graham Hutchings provided experimental evidence of high activity of supported gold catalysts in CO oxidation and acetylene hydrochlorination. Thus, these two researchers challenged the prevailing chemists’ belief that gold is almost completely chemically inert and catalytically inactive. Since then, gold catalysis has been constantly in the centre of attention of a wide array of scientists from around the world. However, there are still many questions about the nature of catalysts containing this noble metal, which inspires in-depth research in this field. From among various potential supports for gold heterogeneous catalysts, zeolites have drawn much attention thanks to several unique properties of this group of materials, among which the most important are high thermal stability and the presence of a system of pores of strictly defined sizes. Zeolites have extremely large surface area, which is desirable to obtain high dispersion of the active phase. The article provides a concise overview of the methods of gold nanoparticles deposition on zeolitic supports and catalytic applications of such materials. The first chapter sheds light on the properties of bulk and nano-sized Au and depicts the background of gold catalysis development. In the following part, a brief description of zeolites and their properties is delivered. The third chapter is devoted entirely to the description of several preparation methods of zeolite-supported gold catalysts and their applications in different catalytic processes. The following post-synthetic methods of zeolite modification with gold are described: impregnation, ion exchange, deposition-reduction, chemical vapour deposition, and grafting. The most important advantages and disadvantages of each method are summarized. The article concludes with a résumé of literature reports concerning the use of zeolitesupported gold catalysts in various processes. Special attention was paid to selective oxidation of alcohols and biomass-derived chemicals (e.g. glucose).
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 11-12; 1259--1293
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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