Search results for " Polymer"

Direct P-functionalization of azobenzene by a cationic phosphidozirconocene complex.

2016

International audience; We report that the cationic phosphidozirconocene complex [(eta(5)-C5H5)(2)Zr(PCy2)][CH3B(C6F5)(3)] (II) reacts with azobenzene, resulting in the expedient formation of Zr complex (2) bound to a tridentate PNN ligand. This reaction proceeds by a mechanism of cooperative nucleophilic substitution of hydrogen. The intermediate sigma(H) adduct (1) has been characterized by NMR spectroscopy.

Influence of aryl hydrocarbon- (Ah) receptor and genotoxins on DNA repair gene expression and cell survival of mouse hepatoma cells

2009

The aryl hydrocarbon receptor (AhR) mediates toxicity of a variety of environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs) and dioxins. However, the underlying mechanisms and genetic programmes regulated by AhR to cause adverse effects but also to counteract poisoning are still poorly understood. Here we analysed the effects of two AhR ligands, benzo[a]pyrene (B[a]P), a DNA damaging tumour initiator and promotor and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a pure tumour promoter, on cell survival and on nucleotide excision repair (NER) gene expression. NER deals with so called "bulky" DNA adducts including those generated by enzymatically activated B[a]P. Therefore, t…

Remarkable effect of organoaluminum activator on catalytic performance of bis(phenoxy-imine) titanium complexes in ethylene polymerization

2009

Zsyntezowano i sprawdzono w polimeryzacji etylenu, po uprzedniej aktywacji zarówno MAO, jak i prostymi związkami glinoorganicznymi (Et3Al, Et2AlCl, EtAlCl2), trzy kompleksy tytanu z ligandami fenoksy-iminowymi: dichlorek bis[N-(3,5-di-tert-butylosalicylideno)anilino]tytanu(IV) (kompleks I), dichlorek bis[N-(3,5-di-tert-butylosalicylideno)-1-naftyloamino]tytanu(IV) (kompleks II) i dichlorek bis[N-(salicylideno)-1-naftyloamino]tytanu(IV) (kompleks III). Stwierdzono, że zarówno struktura ligandów, jak i rodzaj glinoorganicznego aktywatora mają wpływ na aktywność badanych kompleksów. Kompleks I, zawierający podstawnik fenylowy przy iminowym atomie azotu okazał się najaktywniejszy w połączeniu z…

Removal of silicon from CFB-derived fly ash leachate in the context of phosphorus recovery

2018

High concentrations of dissolved silica in the acid leachate impose two major challenges on precipitation based recovery of phosphorus (P). Firstly, co-precipitation of colloidal silica in the acidic regimes decreases the purity and value of precipitated P-products. In addition, silica scaling on internal surfaces of equipment is also a problematic issue in industrial operations. Therefore, removal of dissolved silica prior to P-recovery process minimizes the risks of Si-contamination in P-products and Si-scaling. In the present study, silica removal was achieved by accelerated silica polymerization with higher acidity and ionic strength of mineral acid, which also assisted the leaching of …

Plasma polymer films and gold nanoparticles: coupling of properties to design a biosensor

The present investigation deals with the functionalization of gold nanoparticles (Au NPs) with primary amine-based plasma polymer films (NH2-PPF), to improve their properties for bioanalytical applications. Cyclopropylamine (CPA) plasma polymerization, in pulsed and continuous wave radio frequency discharges, was employed to growth CPA amino-based PPFs coatings (18 nm) onto Au NPs of 12 nm of diameter deposited on glass and silicon substrates. A multi-technique investigation, based on FT-IR and XPS spectroscopies, AFM and SEM microscopies and Tof-SIMS spectrometry, revealed peculiar features of the CPA PPFs. In particular, by FT-IR it was possible to obtain an overview about the rich chemis…

Toward Sustainable PLA-Based Multilayer Complexes with Improved Barrier Properties

2019

Poly(lactic acid) or PLA is currently considered as one of the most promising substitutes of conventional plastics, with low environmental impact, especially for food packaging applications. Nevertheless, some drawbacks, such as high permeability to oxygen, are still limiting its industrial applications. The objective of this study was to highly increase the oxygen barrier performance of PLA without compromising its sustainable nature and following the principles of circular economy perspective. Coproducts coming from mill industries, such as wheat gluten proteins (WG), were used to produce PLA-WG-PLA multilayer complexes with improved barrier performance. Different technologies of industri…

Facile and efficient chemical functionalization of aliphatic polyesters by cross metathesis

2016

International audience; An effective preparation of new tailor-made macromolecular materials via a combination of two (atom-efficient) catalytic transformations is reported. First, new aliphatic polyesters with alternated composition have been prepared using a salen aluminum catalyst system. Next, the pendant vinyl moieties in those copolymers have been selectively transformed into various functional groups by metathesis in the presence of homogeneous Grubbs catalysts. The latter metathesis reaction has been optimized in terms of catalytic activity and selectivity, to define the conditions for an effective and safe procedure that does not affect the macromolecular architecture. All polymer …

Silseskwioksany i ich zastosowanie w syntezie materiałów polimerowych

2015

Artykuł stanowi przegląd literatury dotyczącej syntezy oraz charakterystyki materiałów polimerowych zawierających silseskwioksany (POSS). Przedstawiono metody otrzymywania hybrydowych materiałów polimerowych z udziałem funkcjonalizowanych POSS na drodze click chemistry, polikondensacji, poliaddycji, metatezy z otwarciem pierścienia ipolimeryzacji rodnikowej zarówno konwencjonalnej, jak i kontrolowanej (ATRP).

Zastowanie cyklodekstryn w technologii wdrukowania molekularnego

2022

In the last decade molecular imprinted polymers (MIP) have gained great interest in the area of selective recognition various type substances. Scientific work in this field is carried out very intensively - the methods of synthesis are modified and improved, new types of hydride materials are created, as well as new reagents for synthesis. In this case, cyclodextrins (CD) and their analogues show good molecular recognition ability for its unique physical and chemical properties and suitable cavity structure. As a result, these supramolecular ligands can perform various functions in the MIP technology, and the resulting polymeric materials are characterized by high selectivity and binding sp…

Amphoteric, prevailingly cationic L-arginine polymers of poly(amidoamino acid) structure: Synthesis, acid/base properties and preliminary cytocompati…

2013

A linear amphoteric poly(amidoamino acid), L-ARGO7, is prepared by Michael-type polyaddition of L-arginine with N,N′-methylenebisacrylamide. Chain-extension of acrylamide end-capped L-ARGO7 oligomers with piperazine leads to high-molecular-weight copolymers in which L-arginine maintains its absolute configuration. Acid/base properties of L-ARGO7 polymers show isolectric points of ≈10 and positive net average charges per repeating unit at pH = 7.4 from 0.25 to 0.40. These arginine-rich synthetic polymers possibly share some of the unique biological properties of polyarginine cell-permeating peptides. In vitro tests with mouse embryo fibroblasts balb/3T3 clone A31 show that L-ARGO7 polymers a…