Search results for "40"
showing 10 items of 17345 documents
Acid-Labile Surfactants Based on Poly(ethylene glycol), Carbon Dioxide and Propylene Oxide: Miniemulsion Polymerization and Degradation Studies
2017
Partially degradable, nonionic AB and ABA type di- and triblock copolymers based on poly(propylene carbonate) and poly(ethylene glycol) blocks were synthesized via immortal copolymerization of carbon dioxide and propylene oxide, using mPEG or PEG as a macroinitiator, and (R,R)-(salcy)-CoOBzF5 as a catalyst in a solvent-free one-pot procedure. The amphiphilic surfactants were prepared with molecular weights (Mn) between 2800 and 10,000 g·mol−1 with narrow molecular weight distributions (1.03–1.09). The copolymers were characterized using 1H-, 13C- and DOSY-NMR spectroscopy and size exclusion chromatography (SEC). Surface-active properties were determined by surface tension measurements (crit…
Improvements in Rational Design Strategies of Inulin Derivative Polycation for siRNA Delivery.
2016
The advances of short interfering RNA (siRNA)-mediated therapy provide a powerful option for the treatment of many diseases, including cancer, by silencing the expression of targeted genes involved in the progression of the pathology. On this regard, a new pH-responsive polycation derived from inulin, Inulin-g-imidazole-g-diethylenetriamine (INU-IMI-DETA), was designed and employed to produce INU-IMI-DETA/siRNA "Inulin COmplex Nanoaggregates" (ICONs). The experimental results showed that INU-IMI-DETA exhibited strong cationic characteristics and high solubility in the pH range 3-5 and self-aggregation triggered by pH increase and physiological salt concentration. INU-IMI-DETA showed as well…
Halogen-Bonded Co-Crystals of Aromatic N-oxides : Polydentate Acceptors for Halogen and Hydrogen Bonds
2017
The C-ethyl-2-methylresorcinarene (1) forms 1:1 in-cavity complexes with aromatic N,N′-dioxides, only if each of the aromatic rings has an N−O group. The structurally different C-shaped 2,2′-bipyridine N,N′-dioxide (2,2′-BiPyNO) and the linear rod-shaped 4,4′-bipyridine N,N′-dioxide (4,4′-BiPyNO) both form 1:1 in-cavity complexes with the host resorcinarene in C4v crown and C2v conformations, respectively. In the solid state, the host–guest interactions between the 1,3-bis(4-pyridyl)propane N,N′-dioxide (BiPyPNO) and the host 1 stabilize the unfavorable anti-gauche conformation. Contrary to the N,N′-dioxide guests, the mono-N-oxide guest, 4-phenylpyridine N-oxide (4PhPyNO), does not form an…
Pro-Degradant Activity of Naturally Occurring Compounds on Polyethylene in Accelerate Weathering Conditions
2019
In this work, naturally occurring compounds, such as Vitamin E (VE) and Ferulic Acid (FA), at high concentrations, have been considered as pro-degradant agents for Low Density Polyethylene (PE). However, all obtained results using the naturally occurring molecules as pro-oxidant agents for PE have been compared with the results achieved using a classical pro-oxidant agent, such as calcium stearate (Ca stearate) and with neat PE. The preliminary characterization, through rheological, mechanical and thermal analysis, of the PE-based systems highlights that the used naturally occurring molecules are able to exert a slight plasticizing action on PE and subsequently the PE rigidity and crystalli…
Comparative Investigation on the Soil Burial Degradation Behaviour of Polymer Films for Agriculture before and after Photo-Oxidation
2020
Polymer films based on biodegradable polymers, polyethylene (PE) and modified PE with oxo-degradable additive were prepared by film blowing. Carbon black (1%) was added to all the films. Commercial biodegradable Ecovio®
Naturally Occurring Oxazole Structural Units as Ligands of Vanadium Catalysts for Ethylene-Norbornene (Co)polymerization
2021
1,3-Oxazole and 4,5-dihydro-1,3-oxazole are common structural motifs in naturally occurring peptides. A series of vanadium complexes were synthesized using VCl3(THF)3 and methyl substituted (4,5-dihydro-1,3-oxazol-2-yl)-1,3-oxazoles as ligands and analyzed using NMR and MS methods. The complexes were found to be active catalysts both in ethylene polymerization and ethylene-norbornene copolymerization. The position of methyl substituent in the ligand has considerable impact on the performance of (co)polymerization reaction, as well as on the microstructure, and thus physical properties of the obtained copolymers.
Hyaluronan-coated polybenzofulvene brushes as biomimetic materials
2016
Hyaluronic acid (HA) forms pericellular coats in many cell types that are involved in the early stages of cell adhesion by interacting with the CD44 receptor. Based on the largely recognized overexpression of the CD44 receptor in tumor tissues, a polybenzofulvene molecular brush has been enveloped into hyaluronan shells to obtain a tri-component polymer brush (TCPB) composed of intrinsically fluorescent backbones bearing nona(ethylene glycol) arms terminated with low molecular weight HA macromolecules. The nanoaggregates obtained in TCPB water dispersions were characterized on the basis of dimensions, zeta potential, and in vitro cell toxicity. This biomimetic multifunctional material beari…
Impact of Separator Thickness on Temperature Distribution in Single Cell of Polymer Electrolyte Fuel Cell Operated at Higher Temperature of 90 °C and…
2022
The New Energy and Industry Technology Development Organization (NEDO) road map (Japan, 2017) has proposed that a polymer electrolyte fuel cell (PEFC) system, which operates at a temperature of 90 °C and 100 °C, be applied for stationary and mobility usage, respectively. This study suggests using a thin polymer electrolyte membrane (PEM) and a thin gas diffusion layer (GDL), at the same time, to achieve better power-generation performance, at a higher temperature than usual. The focus of this paper is to clarify the effect of separator thickness on the distribution of temperature at the reaction surface (Treact), with the relative humidity (RH) of the supply gasses and initial operation tem…
Amperometric Biosensor and Front-End Electronics for Remote Glucose Monitoring by Crosslinked PEDOT-Glucose Oxidase
2018
Focusing on the interplay between interface chemistry, electrochemistry, and integrated electronics, we show a novel low-cost and flexible biosensing platform for continuous glucose monitoring. The amperometric biosensing system features a planar three-electrode structure on a plastic substrate, and a wireless near-field communication-powered electronic system performing sensor analog front-end, A/D conversion, digital control, and display tasks. The working electrode is made of electropolymerized poly (3,4-ethylenedioxythiophene) film onto a polyethylene terephthalate/gold electrode followed by immobilization of cross-linked glucose oxidase by glutaraldehyde. The advantages offered by such…
Block copolymers from ionic liquids for the preparation of thin carbonaceous shells
2017
This paper describes the controlled radical polymerization of an ionic-liquid monomer by RAFT polymerization. This allows the control over the molecular weight of ionic liquid blocks in the range of 8000 and 22000 and of the block-copolymer synthesis. In this work we focus on block copolymers with an anchor block. They can be used to control the formation of TiO2 nanoparticles, which are functionalized thereafter with a block of ionic-liquid polymer. Pyrolysis of these polymer functionalized inorganic nanoparticles leads to TiO2 nanoparticles coated with a thin carbonaceous shell. Such materials may, e.g., be interesting as battery materials.