Photonic crystals obtained by soap-free emulsion terpolymerization

AbstractThis paper presents the use of soap-free emulsion terpolymerization to obtainphotonic crystals (PCs). Monodisperse latexes resulted from the polymerization of styrene (ST) with 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) at different compositions defined as system A, B and C respectively. The water solubility of the macroradicals determined different nucleation mechanisms in all three cases. The micellar nucleation mechanism was more predominant for generating system A, whereas the homogeneous nucleation was specific for system C. For system B, both nucleation mechanisms werepossible with the same probability. The latexes and the resulted PCs were characterized by optical microscopy (OM), dynamic light scattering (DLS), gel permeation chromatography (GPC) and UV-VIS spectroscopy.

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Novel Amphiphilic Star-Shaped Poly(2-Oxazoline)s with Calix[4]Arene Branching Center

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.899.300 ◽

2021 ◽

Vol 899 ◽

pp. 300-308

Author(s):

Aleksei N. Blokhin ◽

Alla B. Razina ◽

Andrey V. Tenkovtsev

Keyword(s):

Aqueous Solutions ◽

Ring Opening ◽

Gel Permeation Chromatography ◽

Ring Opening Polymerization ◽

Arene Derivative ◽

Vis Spectroscopy ◽

Gel Permeation ◽

Grafting From ◽

Cationic Ring Opening Polymerization

Novel amphiphlic four-arm star-shaped poly (2-alkyl-2-oxazoline) s with calix [4] arene core were synthesized using the “grafting from” approach. The chlorosulfonated calix [4] arene derivative was synthesized and successfully applied as a multifunctional initiator for the cationic ring-opening polymerization of 2-alkyl-2-oxazolines. Obtained star-shaped poly (2-alkyl-2-oxazoline) s were characterized by means of NMR, UV-Vis spectroscopy and gel-permeation chromatography. It was shown that star-shaped poly (2-isopropyl-2-oxazoline) perform thermosensitivity in aqueous solutions.

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Supramolecular poly(L-lactide)s containing terpyridine metal complexes

e-Polymers ◽

10.1515/epoly.2002.2.1.375 ◽

2002 ◽

Vol 2 (1) ◽

Cited By ~ 1

Author(s):

Marcel Heller ◽

Ulrich S. Schubert

Keyword(s):

Mass Spectrometry ◽

Metal Complexes ◽

Phase Transfer ◽

Gel Permeation Chromatography ◽

Diode Array ◽

Maldi Tof Mass Spectrometry ◽

Full Characterization ◽

Maldi Tof ◽

Vis Spectroscopy ◽

Gel Permeation

AbstractChiral poly(L-lactide)s end-capped with a novel terpyridine ligand are synthesized by a controlled coordinative polymerization procedure. The resulting well-characterized macroligands can be complexed under phase-transfer conditions with iron(II) ions to form well-defined supramolecular poly(L-lactide) complexes. The outstanding stability of such coordinative polymers enables the full characterization by gel permeation chromatography (GPC) and MALDI-TOF mass spectrometry. In addition, in-line diode array UV-Vis spectroscopy coupled to GPC was carried out to verify the formation of the poly(ester) complexes.

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Effect of Rapid Thermal Processing on Oxygen Precipitation in Silicon

MRS Proceedings ◽

10.1557/proc-104-197 ◽

1987 ◽

Vol 104 ◽

Author(s):

G. A. Hawkins ◽

J. P. Lavine

Keyword(s):

Heterogeneous Nucleation ◽

Thermal Processing ◽

Homogeneous Nucleation ◽

Critical Radius ◽

Rapid Thermal Processing ◽

Nucleation Mechanism ◽

Oxygen Precipitation ◽

Precipitate Growth ◽

Nucleation Mechanisms ◽

Induced Changes

ABSTRACTThe precipitation of oxygen in silicon can be initiated by both homogeneous and heterogeneous nucleation mechanisms. Homogeneous nucleation has been studied in much greater detail; however, in some cases, superior contaminant gettering has been reported for precipitation processes believed to be based on heterogeneous nucleation. In this study, we use rapid thermal annealing (RTA) to demonstrate conclusively that the nucleation mechanism for one such process is, in fact, heterogeneous. We also investigate the sensitivity of precipitation to slight alterations in thermal process steps. We interpret our results in terms of point-defect-induced changes in the critical radius (Rc) for precipitate growth.

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Copolymers based on N-acryloyl-L-leucine and urea methacrylate with pyridine moieties

Journal of the Serbian Chemical Society ◽

10.2298/jsc150504059b ◽

2016 ◽

Vol 81 (3) ◽

pp. 307-322 ◽

Cited By ~ 2

Author(s):

Emil Buruiana ◽

Mioara Murariu

Keyword(s):

Experimental Data ◽

Gel Permeation Chromatography ◽

Specific Rotation ◽

Optically Active ◽

Molar Ratio ◽

Carboxyl Group ◽

Thermal Methods ◽

Vis Spectroscopy ◽

Gel Permeation ◽

Copolymer Poly

By using free radical polymerization of (N-methacryloyloxyethyl-N?-4-picolyl)-urea (MAcPU) and N-acryloyl-L-leucine (AcLeu), an optically active copolymer, poly[(N-methacryloyloxyethyl-N?-4-picolyl)-urea-co-N-acryloyl-L-leucine], MAcPU-co-AcLeu (1.86:1 molar ratio) was prepared and subsequently functionalized at the pyridine-N with (1R/S)-(?/+)-10-camphorsulfonic acid (R/S-CSA) and at carboxyl group with (R)-(+)-?-ethylbenzylamine (R-EBA) or trans-4-stilbene methanol (t-StM). The structures, chemical composition and chiroptical activity of the monomers and the copolymers were characterized by spectral analysis (FTIR, 1H (13C)-NMR, 1H,1H-COSY, UV/vis), thermal methods (TGA, DSC), fluorescence spectroscopy, gel permeation chromatography and specific rotation measurements. Influence of the optical activity of monomer and modifier on modified copolymers suggested a good correlation between the experimental data obtained (23[?]589=+12.5? for AcLeu and MAcPU-co-AcLeu, 23[?]589=0?+27.5? for (MAcPU-co-AcLeu)-R/S-CSA, 23[?]589=+25? for (MAcPU-co-AcLeu)-R-EBA, and 23[?]589 = 0? for (MAcPU-co-AcLeu)-St). In addition, the photobehavior of the stilbene copolymer (MAcPU-co-AcLeu)-St in film was investigated by UV-vis spectroscopy. The fluorescence quenching of the stilbene species in the presence of aliphatic/aromatic amine in DMF solution was evaluated, more efficiently being 4,4??dipyridyl (detection limit: 7.2 x 10-6 mol/L).

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Exsolution and inversion in pigeonite from the Whin Sill, Northern England

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109513 ◽

1978 ◽

Vol 36 (1) ◽

pp. 474-475

Author(s):

P.P.K. Smith

Keyword(s):

High Temperature ◽

Low Temperature ◽

Homogeneous Nucleation ◽

Silicate Mineral ◽

Antiphase Boundaries ◽

Two Phase ◽

Primitive Form ◽

The Core ◽

Nucleation Mechanisms ◽

And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

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Aggregated, Conformationally Changed Fibrinogen Exposes the Stimulating Sites for t-PA-Catalysed Plasminogen Activation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650269 ◽

1996 ◽

Vol 75 (02) ◽

pp. 326-331 ◽

Cited By ~ 7

Author(s):

Unni Haddeland ◽

Knut Sletten ◽

Anne Bennick ◽

Willem Nieuwenhuizen ◽

Frank Brosstad

Keyword(s):

Conformational Changes ◽

Gel Permeation Chromatography ◽

Tissue Type ◽

Plasminogen Activation ◽

Chromogenic Substrate ◽

Type Plasminogen Activator ◽

Gel Permeation ◽

Self Association ◽

Fibrin Monomers ◽

Stimulation Of

SummaryThe present paper shows that conformationally changed fibrinogen can expose the sites Aα-(148-160) and γ-(312-324) involved in stimulation of the tissue-type plasminogen activator (t-PA)-catalysed plasminogen activation. The exposure of the stimulating sites was determined by ELISA using mABs directed to these sites, and was shown to coincide with stimulation of t-PA-catalysed plasminogen activation as assessed in an assay using a chromogenic substrate for plasmin. Gel permeation chromatography of fibrinogen conformationally changed by heat (46.5° C for 25 min) demonstrated the presence of both aggregated and monomeric fibrinogen. The aggregated fibrinogen, but not the monomeric fibrinogen, had exposed the epitopes Aα-(148-160) and γ-(312-324) involved in t-PA-stimulation. Fibrinogen subjected to heat in the presence of 3 mM of the tetrapeptide GPRP neither aggregates nor exposes the rate-enhancing sites. Thus, aggregation and exposure of t-PA-stimulating sites in fibrinogen seem to be related phenomena, and it is tempting to believe that the exposure of stimulating sites is a consequence of the conformational changes that occur during aggregation, or self-association. Fibrin monomers kept in a monomeric state by a final GPRP concentration of 3 mM do not expose the epitopes Aα-(148-160) and γ-(312-324) involved in t-PA-stimulation, whereas dilution of GPRP to a concentration that is no longer anti-polymerizing, results in exposure of these sites. Consequently, the exposure of t-PA-stimulating sites in fibrin as well is due to the conformational changes that occur during selfassociation.

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