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1.
Angew Chem Int Ed Engl ; 63(33): e202408246, 2024 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-38819775

RESUMO

Improving composite cathode function is key to the success of the solid-state battery. Maximizing attainable cathode capacity and retention requires integrating suitable polymeric binders that retain a sufficiently high ionic conductivity and long-term chemo-mechanical stability of the cathode active material-solid-electrolyte-carbon mixture. Herein, we report block copolymer networks composed of lithium borate polycarbonates and poly(ethylene oxide) that improved the capacity (200 mAh g-1 at 1.75 mA cm-2) and capacity retention (94 % over 300 cycles) of all-solid-state composite cathodes with nickel-rich LiNi0.8Co0.1Mn0.1O2 cathode active material, Li6PS5Cl solid electrolyte, and carbon. Tetrahedral B(OR)2(OH)2 - anions immobilized on the polycarbonate segments provide hydrogen-bonding chain crosslinking and selective Li-counterion conductivity, parameterized by Li-ion transference numbers close to unity (tLi+~0.94). With 90 wt % polycarbonate content and a flexible low glass transition temperature backbone, the single-ion conductors achieved high Li-ion conductivities of 0.2 mS cm-1 at 30 °C. The work should inform future binder design for improving the processability of cathode composites towards commercializing solid-state batteries, and allow use in other cell configurations, such as lithium-sulphur cathode designs.

2.
Molecules ; 29(10)2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38792069

RESUMO

A highly efficient low-cost adsorbent was prepared using raw and chemically modified cellulose isolated from sugarcane bagasse for decontamination of Cr(VI) from wastewater. First, cellulose pulp was isolated from sugarcane bagasse by subjecting it to acid hydrolysis, alkaline hydrolysis and bleaching with sodium chlorate (NaClO3). Then, the bleached cellulose pulp was chemically modified with acrylonitrile monomer in the presence Fenton's reagent (Fe+2/H2O2) to carry out grafting of acrylonitrile onto cellulose by atom transfer radical polymerization. The developed adsorbent (acrylonitrile grafted cellulose) was analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Both raw cellulose and acrylonitrile grafted cellulose were used for chromium removal from wastewater. The effects of metal ion concentration, pH, adsorbent dose and time were studied, and their values were optimized. The optimum conditions for the adsorption of Cr(VI) onto raw and chemically modified cellulose were: metal ion concentration: 50 ppm, adsorbent dose: 1 g, pH: 6, and time: 60 min. The maximum efficiencies of 73% and 94% and adsorption capacities of 125.95 mg/g and 267.93 mg/g were achieved for raw and acrylonitrile grafted cellulose, respectively. High removal efficiency was achieved, owing to high surface area of 79.92 m2/g and functional active binding cites on grafted cellulose. Isotherm and kinetics studies show that the experimental data were fully fitted by the Freundlich isotherm model and pseudo first-order model. The adsorbent (acrylonitrile grafted cellulose) was regenerated using three different types of regenerating reagents and reused thirty times, and there was negligible decrease (19%) in removal efficiency after using it for 30 times. Hence, it is anticipated that acrylonitrile could be utilized as potential candidate material for commercial scale Cr(VI) removal from wastewater.


Assuntos
Acrilonitrila , Celulose , Cromo , Saccharum , Águas Residuárias , Poluentes Químicos da Água , Purificação da Água , Celulose/química , Cromo/isolamento & purificação , Cromo/química , Acrilonitrila/química , Saccharum/química , Águas Residuárias/química , Adsorção , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
3.
Polymers (Basel) ; 15(15)2023 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-37571053

RESUMO

Collagen is a suitable material for regenerative medicine because it is characterized by its good biocompatibility. However, due to its fibrillar structure, it cannot organize itself into three-dimensional porous structures without additional modification. The introduction of synthetic monomer elements into the collagen macromolecules is a technique used to form three-dimensional, collagen-based, branched, and crosslinked structures. New types of graft copolymers made from cod collagen with a butyl acrylate and vinyl butyl ether copolymer in aqueous dispersion were obtained in the presence of triethylborane by a radical mechanism. The process of graft copolymer formation proceeded as usual by radical initiation, through radicals formed during triethylborane oxidation by oxygen residues, collagen borination, and reversible inhibition with the participation of a boroxyl radical. The characteristics of the graft copolymers were determined using methods of physical and chemical analysis (GPC, SEM, IR spectroscopy, etc.), while the cytotoxicity was assessed using the MTT assay method. It is shown that the grafting of alternating blocks of butyl acrylate and vinyl butyl ether to the protein macromolecules results in changes in the morphological pattern of the graft co-polymer in comparison with native collagen. This is manifested in the development of consolidations around the collagen fibers of the structural matrices, with the co-polymer cellular structure consisting of interpenetrating pores of unequal size. Additionally, it is important that the graft co-polymer solutions are not toxic at a certain concentration. The above properties confirm the promising nature of the technique's application as the basis for producing new materials for regenerative medicine.

4.
Polymers (Basel) ; 15(1)2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36616587

RESUMO

The ability of poly-ferric-silicate-sulphate (PFSS) synthesized via a co-polymerization process has been applied for the removal of diazo Congo red dye. A novel degradation pathway of diazo Congo red dye by using PFSS is proposed based on LC-MS analysis. Diazo Congo red dye was successfully removed using synthesized PFSS at lower coagulant dosages and a wider pH range, i.e., 9 mg/L from pH 5 to 7, 11 mg/L at pH 9, and 50 mg/L at pH 11. The azo bond cleavage was verified by the UV-Vis spectra of diazo Congo red-loaded PFSS and FTIR spectra which showed disappearance of the peak at 1584 cm-1 for -N=N- stretching vibrations. The synchronized results of UV-Vis spectra, FTIR, and the LC-MS analysis in this study confirmed the significance of the Si and Fe bond in PFSS towards the degradation of diazo Congo red dye. The successfully synthesized PFSS coagulant was characterized by FTIR, SEM, TEM, and HRTEM analysis. From this analysis, it was proven that PFSS is a polycrystalline material which is favorable for the coagulation-flocculation process. Based on all these findings, it was established that synthesized PFSS can be employed as a highly efficient polymeric coagulant for the removal of dye from wastewater.

5.
Angew Chem Int Ed Engl ; 62(5): e202212235, 2023 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-36413108

RESUMO

Radical polymerization (RP) of multivinyl monomers (MVMs) provides a facile solution for manipulating polymer topology and has received increasing attention due to their industrial and academic significance. Continuous efforts have been made to understand their mechanism, which is the key to regulating materials structure. Modelling techniques have become a powerful tool that can provide detailed information on polymerization kinetics which is inaccessible by experiments. Many publications have reported the combination of experiments and modelling for free radical polymerization (FRP) and reversible-deactivation radical polymerizations (RDRP) of MVMs. Herein, a minireview is presented for the most important modelling techniques and their applications in FRP/RDRP of MVMs. This review hopes to illustrate that the combination of modelling and wet experiments can be a great asset to polymer researchers and inspire new thinking for the future MVMs experiment optimization and product design.

6.
J Colloid Interface Sci ; 624: 411-422, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35660909

RESUMO

Well-organized water splitting semiconducting photocatalyst is an important concept, but stimulating aimed at decisive energy and environmental emergencies. In this context, visible light-based photocatalytic water splitting with low-dimensional semiconducting materials is proposed to produce sustainable energy. Here we optimized the sequential of organic electron-rich heterocyclic monomer namely benzothiadiazole (BTD) quenched within polymeric carbon nitride (PCN) semiconductor via copolymerization, thereby assembling a sanctum of donor-π-acceptor (D-π-A) photocatalysts. The selection of BTD is based on the benzene ring, which consequently anticipating a π cross-linker unit for hydrogen and oxygen evolution. A hydrogen evolution rates (HER) of 88.2 µmol/h for pristine PCN and 744.2 µmol/h for PCN-BTD008 (eight times higher than pure PCN) are observed. Additionally, a remarkable apparent quantum yield (AQY) of about 58.6% at 420 nm has been observed for PCN-BTD008. Likewise, the oxygen evolution rate (OER) data reflect the generation of 0.2 µmol/h1 (visible) and 1.6 µmol/h1 (non-visible) for pure PCN. Though, OER of PCN-BTD008 is found to be 2.2 µmol/h1 (visible) and 14.8 µmol/h1 (non-visible), which are economically better than pure PCN. As such, the results show an important step toward modifying the design and explain a vital part of the D-π-A scheme at a balanced theme for fruitful photocatalysts intended for future demand.

7.
Polymers (Basel) ; 14(7)2022 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-35406299

RESUMO

A family of half-titanocene complexes bearing π,π-stacked aryloxide ligands and their catalytic performances towards ethylene homo-/co- polymerizations were disclosed herein. All the complexes were well characterized, and the intermolecular π,π-stacking interactions could be clearly identified from single crystal X-ray analysis, in which a stronger interaction could be reflected for aryloxides bearing bigger π-systems, e.g., pyrenoxide. Due to the formation of such interactions, these complexes were able to highly catalyze the ethylene homopolymerizations and copolymerization with 1-hexene comonomer, even without any additiveson the aryloxide group, which showed striking contrast to other half-titanocene analogues, implying the positive influence of π,π-stacking interaction in enhancing the catalytic performances of the corresponding catalysts. Moreover, it was found that addition of external pyrene molecules was capable of boosting the catalytic efficiency significantly, due to the formation of a stronger π,π-stacking interaction between the complexes and pyrene molecules.

8.
Polymers (Basel) ; 12(9)2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32878280

RESUMO

Homo- and copolymers of propylene and 1-decene were synthesized by controlled chain-walking (co)polymerization using phenyl substituted α-diimine nickel complexes activated with modified methylaluminoxane (MMAO). This catalytic system was found to polymerize propylene in a living fashion to furnish high molecular weight ethylene-propylene (EP) copolymers. The copolymerizations proceeded to give high molecular weight P/1-decene copolymers with narrow molecular weight distribution (Mw/Mn ≈ 1.2), which indicated a living nature of copolymerization at room temperature. The random copolymerization results indicated the possibility of precise branched structure control, depending on the polymerization temperature and time.

9.
Int J Biol Macromol ; 148: 248-257, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31954791

RESUMO

The present work deals with the design of the alginate, sterculia gum polysaccharide and PVP based hydrogel for brain drug delivery applications. The release dynamics of citicoline drug, a nerve regenerating agent, was evaluated. The polymers were investigated by Cryo-SEMs, AFM, FTIR, XRD, 13C NMR, and swelling studies. The drug release occurred slowly without burst effect and followed mechanism that was approaching the Fickian diffusion mechanism and first order kinetic model. The polymer matrix showed drug loading 40.0 ± 0.8%, thrombose percentage 68.70 ± 8.95%, hemolytic index value 3.66 ± 1.65%, detachment force from the intestinal mucosa = 0.124 ± 0.04 N, and tensile strength 7.67 ± 0.40 N/mm2. These films were found biocompatible, antioxidant and mucoadhesive and could be explored for brain drug delivery.


Assuntos
Alginatos/química , Encéfalo/metabolismo , Hidrogéis/química , Goma de Karaya/química , Sterculia/química , Difusão , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Polimerização/efeitos dos fármacos , Polímeros/química , Polissacarídeos/química , Termogravimetria/métodos
10.
Carbohydr Polym ; 230: 115664, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31887927

RESUMO

Erlotinib-loaded carboxymethyl temarind gum-g-poly(N-isopropylacrylamide)-montmorillonite based semi-IPN nanocomposites were synthesized and characterized for their in vitro performances for lung cancer therapy. The placebo matrices exhibited outstanding biodegradability and pH-dependent swelling profiles. The molar mass (M¯ c) between the crosslinks of these composites was declined with temperature. The solid state characterization confirmed the semi-IPN architecture of these scaffolds. The corresponding drug-loaded formulations displayed excellent drug-trapping capacity (DEE, 86-97 %) with acceptable zeta potential (-16 to -13 mV) and diameter (967-646 nm). These formulations conferred sustained drug elution profiles (Q8h, 77-99 %) with an initial burst release. The drug release profile of the optimized formulation (F-3) was best fitted in the first order kinetic model with Fickian diffusion driven mechanism. The mucin adsorption to F-3 followed Langmuir isotherms. The results of MTT assay, AO/EB staining and confocal analyses revealed that the ERL-loaded formulation suppressed A549 cell proliferation and induced apoptosis more effectively than pristine drug.


Assuntos
Portadores de Fármacos/química , Cloridrato de Erlotinib/administração & dosagem , Nanocompostos/química , Células A549 , Portadores de Fármacos/uso terapêutico , Liberação Controlada de Fármacos , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Nanocompostos/uso terapêutico
11.
Data Brief ; 28: 104878, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31879697

RESUMO

This work describes an approach towards experimental implementation of real time control studies conducted on a batch polymerization reactor. The information is related to the controlling of molecular weight for styrene acrylonitrile copolymer polymerization system in a batch reactor generated under a varied range of temperatures, reactant concentrations and retention times. The operating conditions of 6 hrs and temperature of 343 K for yielding a molecular weight in the range of 39,900-40,000 gmol-1 is established using simulation studies. A real time control facility consisting of a batch reactor, data acquisition software "LabVIEW" and a PC for monitoring and control is used to implement these operating conditions. The resulting product is analyzed by gel permeation chromatography (GPC). The data generated can be used by researchers, academicians and industry for generating control strategies, automation and scale up of polymerization reactors.

12.
Int J Biol Macromol ; 143: 60-75, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31812747

RESUMO

For the first time, stable LBG-cl-Poly(DMAAm) hydrogel is prepared via free radical in situ polymerization of N, N-dimethyl acrylamide by employing N, N'-methylene bis(acrylamide) as cross-linkers. The hydrogel was characterized by different physicochemical techniques like equilibrium swelling percentage, point of zero charges (pHPZC), FTIR, SEM, and TGA. The LBG-cl-Poly(DMAAm) hydrogel was used in experiments on swelling behavior and adsorption of water-soluble cationic dye-Brilliant green (BG). The influence of pH on the structural change of BG dye was discussed. The swelling of hydrogel was sensitive toward the pH, ionic strength, and temperature stimuli. Adsorption behavior of hydrogel was investigated for the adsorption of BG dye and it was found to highly efficient in removing 97.7% of BG dye in 50 mg L-1 of dye solution. Adsorption data displayed that the adsorption of BG followed the pseudo-second-order kinetic model (R2 = 0.998) and Langmuir isotherm model (R2 = 0.988) with a maximum adsorption capacity of 142.85 mg g-1. The developed LBG-cl-Poly(DMAAm) hydrogel demonstrated efficient separation of BG dye and maintained maximum adsorption capacity after 6th regeneration cycles. The results indicated that LBG-cl-Poly(DMAAm) hydrogel can be used as an alternative and promising adsorbent to be applied in the treatment of effluents containing the BG dye.


Assuntos
Corantes/química , Galactanos/química , Hidrogéis/química , Mananas/química , Gomas Vegetais/química , Purificação da Água , Adsorção , Técnicas de Química Sintética , Concentração de Íons de Hidrogênio , Cinética , Modelos Químicos , Estrutura Molecular , Polimerização , Solventes , Temperatura , Água , Poluentes Químicos da Água/química , Purificação da Água/métodos
13.
Front Chem ; 8: 621898, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33598449

RESUMO

Heterogeneous phase astrochemistry plays an important role in the synthesis of complex organic matter (COM) as found on comets and rocky body surfaces like asteroids, planetoids, moons and planets. The proposed catalytic model is based on two assumptions: (a) siliceous rocks in both crystalline or amorphous states show surface-exposed defective centers such as siloxyl (Si-O•) radicals; (b) the second phase is represented by gas phase CO molecules, an abundant C1 building block found in space. By means of quantum chemistry; (DFT, PW6B95/def2-TZVPP); the surface of a siliceous rock in presence of CO is modeled by a simple POSS (polyhedral silsesquioxane) where a siloxyl (Si-O•) radical is present. Four CO molecules have been consecutively added to the Si-O• radical and to the nascent polymeric CO (pCO) chain. The first CO insertion shows no activation free energy with ΔG200K = -21.7 kcal/mol forming the SiO-CO• radical. The second and third CO insertions show Δ G 200 K ‡ ≤ 10.5 kcal/mol. Ring closure of the SiO-CO-CO• (oxalic anhydride) moiety as well as of the SiO-CO-CO-CO• system (di-cheto form of oxetane) are thermodynamically disfavored. The last CO insertion shows no free energy of activation resulting in the stable five member pCO ring, precursor to 1,4-epoxy-1,2,3-butanone. Hydrogenation reactions of the pCO have been considered on the SiO oxygen or on the carbons and oxygens of the pCO chains. The formation of the reactive aldehyde SiO-CHO on the siliceous surface is possible. In principle, the complete hydrogenation of the (CO)1-4 series results in the formation of methanol and polyols. Furthermore, all the SiO-pCO intermediates and the lactone 1,4-epoxy-1,2,3-butanone product in its radical form can be important building blocks in further polymerization reactions and/or open ring reactions with H (aldehydes, polyols) or CN (chetonitriles), resulting in highly reactive multi-functional compounds contributing to COM synthesis.

14.
J Colloid Interface Sci ; 554: 627-639, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31344529

RESUMO

The intertwined exploring of solar water driven into chemical energy configurated by a constituted semiconductor photocatalyst under sunlight approach toward a remediation eager method that solve the environmental issues. Currently we optimized polymeric carbon nitride PCN by a sophisticated molecular co-polymerization process which diffused with a mirror organic conjugated heterocyclic monomer to maximize its photocatalytic activity. Herein, for the 1st time we report an organic π-electron stacking conjugated thiazolothiazole (TT) as a small molecule within the framework of PCN to enhance the conductive optical and photocatalytic properties of PCN under solar energy irradiation. The fusion of this bicyclic thiazolothiazole (TT) co-monomer within PCN remarkably enhanced the charge carrier motilities and giving a rigid packing due to sulfur contents. Excitingly the as-synthesized samples were processed under different liberated characterization such as XRD, FTIR, BET, SEM, TEM, XPS, PL, DRS and EPR under both regions respectively. Results reflect that the integration of thiazolothiazole (TT) in the heptazine structure of PCN alter a prodigious delocalization in its π-conjugated system and similarly demonstrating an apparent fluctuation in its surface area, electronic structure, its calculated band gap, chemical composition analysis and maximize the process of generation of electrons under solar light from ground state (HOMO) to the excited state (LUMO) of polymeric carbon nitride (PCN). Beside, this unique integrity of TT co-monomer with in PCN matrix remarkably improve the photocatalytic activity toward prosperity and the amount optimized CNU-TT12.0 demonstrated an outstanding photocatalytic activity of water reduction for H2 evolution and as well of RhB pollutant photodegradation. The sample optimized display 10.6 enhancement comparatively pure pristine sample.

15.
Mater Sci Eng C Mater Biol Appl ; 94: 150-160, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30423696

RESUMO

This work describes the development of antifouling functional coatings on the surface of low density polyethylene (LDPE) films by means of atmospheric pressure non-thermal plasma (APNTP) assisted copolymerization using a mixture of acrylic acid and poly (ethylene glycol). The aim of the study was to investigate the antifouling properties of the plasma copolymerized LDPE films and the same was carried out as a function of deposition time with fixed applied potential of 14 kV. In a second stage, the plasma copolymerized LDPE films were functionalized with chitosan (CHT) to further enhance its antifouling properties. The surface hydrophilicity, structural, topographical and chemistry of the plasma copolymerized LDPE films were examined by contact angle (CA), X-ray diffraction (XRD), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Coating stability was also studied in detail over a storage time of 15 days by storing in water and air. The antifouling properties of the plasma copolymerized LDPE films were examined via protein adsorption and platelet adhesion studies. CA study showed significant changes in surface wettability after the coating process. XPS and FTIR analysis proved the presence of a dense multifunctional coating and an efficient immobilization of CHT. Substantial amendments in surface topography were observed, positively enhancing the overall surface hydrophilicity. Finally, in-vitro analysis showed excellent antifouling behavior of the surface modified LDPE films.


Assuntos
Incrustação Biológica , Quitosana/farmacologia , Gases em Plasma/química , Polietileno/química , Polimerização , Adsorção , Animais , Proteínas Sanguíneas/metabolismo , Materiais Revestidos Biocompatíveis/química , Cabras , Humanos , Interações Hidrofóbicas e Hidrofílicas , Teste de Materiais , Espectroscopia Fotoeletrônica , Adesividade Plaquetária , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Molhabilidade , Difração de Raios X
16.
Talanta ; 186: 53-59, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29784398

RESUMO

Interference rejection in amperometric biosensors can be more effective introducing some modifiers during electro-deposition of permselective film. Addition of ß-cyclodextrin (ßCD), a cyclic oligosaccharide composed of seven glucose units, to the ortho-phenylendiamine (oPD) monomer were already demonstrated to provide an enhancement in ascorbic acid (AA) rejection. Here we evaluated the improvement in permselectivity of poly-eugenol and poly-magnolol films electro-polymerized in presence of different amounts of ßCD or eugenol-ßCD inclusion complex for amperometric biosensor application. Starting from Pt-Ir wire as transducer several microsensors were covered with polymeric films doped with ßCD-based modifiers through constant potential amperometry. Characterization of modified polymers was achieved by scanning electron microscopy and permselectivity analysis. Poly-magnolol film in combination with ßCD showed a worsening in permselectivity compared to poly-magnolol alone. In contrast, the introduction of ßCD-based modifier enhanced the interference rejection toward the archetypal interferent AA, while slightly affecting permeability toward H2O2 compared to the poly-eugenol without modifier. The AA rejection seems to be influenced by the availability of ßCD cavity as well as film performance due to concentration of ßCD-Eugenol inclusion complex. A poly-eugenol film co-polymerized with 2 mM ßCD-eugenol inclusion complex showed a permselectivity equal to poly-orthophenylendiamine film (PPD), with a lower permeability to AA, likely to be related with a self-blocking mechanism. Based on these results, a biosensor for glutamate was constructed with a poly-eugenol doped with ßCD-eugenol as permselective layer and its permselectivity, stability and lifetime were determined.


Assuntos
Ácido Ascórbico/química , Técnicas Biossensoriais , Técnicas Eletroquímicas , Ácido Glutâmico/análise , beta-Ciclodextrinas/química , Compostos de Bifenilo/química , Eugenol/química , Lignanas/química , Polímeros/química
17.
Polymers (Basel) ; 10(6)2018 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-30966719

RESUMO

We review the development and application of an organic polymer-gel capable of producing fixed, three-dimensional fluorescent images of complex radiation fields. The gel consists for more than 99% of γ-ray-polymerized (~15% conversion) tertiary-butyl acrylate (TBA) containing ~100 ppm of a fluorogenic compound, e.g., maleimido-pyrene (MPy). The radio-fluorogenic effect depends on copolymerization of the MPy into growing chains of TBA on radiation-induced polymerization. This converts the maleimido residue, which quenches the pyrene fluorescence, into a succinimido moeity (SPy), which does not. The intensity of the fluorescence is proportional to the yield of free-radicals formed and hence to the local dose deposited. Because the SPy moieties are built into the polymer network, the image is fixed. The method of preparing the gel and imaging the radiation-induced fluorescence are presented and discussed. The effect is illustrated with fluorescent images of the energy deposited in the gel by beams of X-rays, electrons, and protons as well as a radioactive isotope.

18.
Electrophoresis ; 38(22-23): 3020-3028, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28722219

RESUMO

In this study, a novel functional monomer N-[1-(α-naphthyl)ethylaminocarbonyl]-D-tert-leucine-[2-(methacryloyloxy)ethyl] amide (NA-D-tert-Leu-MA) was synthesized, and then employed to prepare polymeric monoliths (240 mm × 100 µm id) functionalized with tert-leucine derivative through a single step thermo-initiated co-polymerization approach or a multi-step post-modification approach. The multi-step approach involves the post-modification of a thiol-containing monolith with NA-D-tert-Leu-MA via "thiol-ene"click reaction. The physicochemical properties of the resulting monoliths were characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry and micro-liquid chromatography. Good column stability, permeability, efficiency and reproducibility were obtained for the optimized monoliths. The poly (NA-D-tert-Leu-MA-co-ethylene dimethacrylate) monolith prepared through the single step co-polymerization approach exhibited satisfactory achiral separation performance for various analytes, including phenols, aniline derivatives and intact proteins, while its enantioseparation ability is rather poor. In contrast to that, the monolith prepared through the multi-step post-modification approach showed much higher enantioselectivity for 7-nitro-2,1,3-benzoxadiazole (NBD)-derivatized amino acids. Three NBD-derivatized amino acids (theanine, proline and norleucine) could be baseline enantioseparated.


Assuntos
Cromatografia Líquida/métodos , Polímeros/química , Valina/análogos & derivados , Leucina/análogos & derivados , Microtecnologia , Polimerização , Reprodutibilidade dos Testes , Estereoisomerismo , Valina/química
19.
Macromol Rapid Commun ; 38(2)2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27859900

RESUMO

(Co)Polymers containing pentafluorophenylacetylene (F5 PA) have been prepared for the first time mediated by [Rh(nbd)Cl]2 /NEt3 to give materials with properties typical of poly(phenylacetylene)s prepared with this catalyst/co-catalyst combination. It is demonstrated that the F5 PA repeat units in these new (co)polymers serve as convenient reactive species for post-polymerization modification with thiols via para-fluoro aromatic nucleophilic substitution reactions to give an entirely new family of novel thioether-functional polyene materials accompanied by absorption maxima shifts of up to 130 nm. Finally, the electrochemical properties of these new fluorinated polyene materials are briefly examined and the distinct difference in behavior of the F5 PA homopolymer versus polyphenylacetylene, copolymers, and functional derivatives is highlighted.


Assuntos
Técnicas Eletroquímicas , Hidrocarbonetos Fluorados/química , Hidrocarbonetos Fluorados/síntese química , Polienos/química , Polienos/síntese química , Estrutura Molecular , Polimerização
20.
Polymers (Basel) ; 9(4)2017 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30970801

RESUMO

In this work, we studied propylene polymerization using some α-diimine palladium catalysts with systematically varied ligand sterics. In propylene polymerization, the ligand steric effect exhibits significant variations on the catalytic activity, polymer molecular weight, and branching density. However, the regio control for the polymer microstructure is poor. Furthermore, copolymerization of 1-octene with the highly challenging and biorenewable comonomer acrylic acid was investigated. High copolymer molecular weights and high comonomer incorporation ratios could be achieved in this system. This study provides a novel access for the direct synthesis of branched carboxylic acid functionalized polyolefins.

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