Search results for "polymer"
showing 10 items of 10504 documents
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…
Non-conventional synthesis and photophysical studies of platinum(ii) complexes with methylene bridged 2,2′-dipyridylamine derivatives
2019
Methylene bridged 2,2′-dipyridylamine (dpa) derivatives and their metal complexes possess outstanding properties due to their inherent structural flexibility. Synthesis of such complexes typically involves derivatization of dpa followed by coordination on metals, and may not always be very efficient. In this work, an alternative synthetic approach, involving the derivatization step after – rather than prior to – coordination of dpa on metal center, is proposed and applied to synthesis of a number of platinum(II) complexes with substituted benzyldi(2-pyridyl)amines. Comparison with the more conventional synthetic route reveals greater efficiency and versatility of the proposed approach. The …
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 …
Polypropylene/polyhedral oligomeric silsesquioxane nanocomposites – study of free volumes, crystallinity degree and mass flow rate
2016
Nanokompozyty polipropylen/poliedryczne oligomeryczne silseskwioksany (PP/POSS) przygotowano metodą mieszania w stanie stopionym polimeru. Wpływ struktury oraz ilości zastosowanych nanonapełniaczy POSS na objętości swobodne w polipropylenie określono z zastosowaniem spektroskopii czasów życia pozytonów (PALS). Ustalono zależności pomiędzy parametrami PALS: czasem życia o-Ps (τ3) i natężeniem (I3) składowej o-Ps oraz wartościami stopnia krystaliczności (Xc ) i masowego wskaźnika szybkości płynięcia (MFR) badanych materiałów. Obecność nanonapełniaczy POSS wpłynęła na liczbę i rozmiary objętości swobodnych w polimerze, co spowodowało zmianę mikrostruktury osnowy polipropylenowej. Wraz ze zwięk…
Polimeryzacja koordynacyjna alkenylosilseskwioksanów i ich kopolimeryzacja z olefinami lub styrenem
2015
Artykuł stanowi kontynuację przeglądu literatury dotyczącej koordynacyjnej polimeryzacji silseskwioksanów (POSS), zawierających zdolne do polimeryzacji wiązanie podwójne, oraz ich kopolimeryzacji głównie zolefinami, a także ze styrenem. Zastosowanie katalizatorów metalocenowych aktywowanych metyloaluminoksanem (MAO) zapewnia efektywną (ko)polimeryzację silseskwioksanów zarówno z olefinami, jak i styrenem. Wprowadzenie do materiału polimerowego komonomeru POSS korzystnie wpływa na właściwości otrzymanych produktów, które cechują się większą odpornością termiczną oraz wytrzymałością mechaniczną niż ich odpowiedniki niezawierające POSS.
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…