Copolymers Obtained by ε-Caprolactam and Methyl Methacrylate Polymerization in the Presence of Polyimides

2009 ◽  
Vol 21 (5) ◽  
pp. 579-595 ◽  
Author(s):  
Yakov S. Vygodskii ◽  
Tat'yana V. Volkova ◽  
Tat'yana L. Batalova ◽  
Olesya N. Zabegaeva ◽  
Elena M. Belavtseva ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Methyl Methacrylate ◽  
Compression Modulus ◽  
Size Exclusion ◽  
Mechanical And Tribological Properties ◽  
Copolymer Films ◽  
Polymer Properties ◽  
Methyl Methacrylate Polymerization ◽  
Exclusion Chromatography ◽  
Kinetics Of

New copolymers have been synthesized by anionic or radical photopolymerization of ε-caprolactam or methyl methacrylate (MMA) in the presence of dissolved polyimides bearing hexafluoroisopropylidene, fluorene or other groups. Using diimides as models it was shown that the kinetics of anionic polymerization of ε-caprolactam depends on the nature of spacer between the imide cycles. The mechanical and tribological properties of copolymers, their water absorbance and the microstructure of copolymer films were studied. It was found that upon the selection of polyimide activator it was possible to gain the desirable control over the polymer properties, namely, the gel fraction content, phase composition, compression modulus, notched Izod impact strength, friction coefficient and temperature of frictional contact. The kinetics of radical polymerization of MMA in the presence of polyimide and model diimide has been studied by differential scanning photocalorimetry and infrared spectroscopy. From the results of the reaction kinetics and the study of polymer structures by Fourier transform infrared spectroscopy, nuclear magnetic resonance, size-exclusion chromatography and thermogravimetric analysis it has been established that radical photopolymerization of MMA in the presence of polyimide leads to the formation of copolymers owing to chain transfer reactions and/or chain termination by the relevant condensation polymer. It has been established that the imide cycles play a significant role in the formation of both copolymers with ε-caprolactam and MMA, respectively.

scholarly journals Copolymers Formation by Photopolymerization of (Meth)acrylates Containing Dissolved Polyheteroarylenes

2009 ◽  
Vol 2009 ◽  
pp. 1-11 ◽  
Author(s):  
Dmitriy A. Sapozhnikov ◽  
Tat'yana V. Volkova ◽  
Antonina A. Sakharova ◽  
Rashid G. Gasanov ◽  
Vanda Yu. Voytekunas ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Size Exclusion ◽  
Transfer Reactions ◽  
Resonance Spectroscopy ◽  
Vinyl Monomers ◽  
The Novel ◽  
Model Compounds ◽  
Spin Resonance ◽  
Exclusion Chromatography ◽  
Kinetics Of

Radical photopolymerization of (meth)acrylates in the presence of dissolved polyheteroarylenes has been investigated. The kinetics of radical polymerization of unsaturated monomers in the presence of polyheteroarylenes and model compounds has been studied by Differential Scanning Photocalorimetry and Infrared Spectroscopy. From the results of investigations into the kinetics and the polymer structures (Fourier Transform Infrared Spectroscopy, Nuclear Magnetic Resonance, Size-exclusion Chromatography, Thermogravimetric analysis), it has been established that radical photopolymerization of vinyl monomers in the presence of polyheteroarylenes leads to the formation of copolymers owing to chain transfer reactions and/or chain termination by the relevant condensation polymer. Using Electron Spin Resonance Spectroscopy the novel radicals upon the addition of model compounds for the polyheteroarylenes have been detected, and a mechanism of copolymer formation has been proposed.

Kinetic and structural analysis of the ultrasensitive behaviour of cyanobacterial ADP-glucose pyrophosphorylase

2000 ◽  
Vol 350 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Diego F. GÓMEZ CASATI ◽  
Miguel A. AON ◽  
Alberto A. IGLESIAS
Keyword(s):  
Conformational Changes ◽  
Tertiary Structure ◽  
Fluorescence Emission ◽  
Maximal Activity ◽  
Size Exclusion ◽  
Exclusion Chromatography ◽  
Adp Glucose Pyrophosphorylase ◽  
Kinetics Of ◽  
Allosteric Regulators

The kinetic and (supra)molecular properties of the ultrasensitive behaviour of ADP-glucose pyrophosphorylase (AGPase) from Anabaena PCC 7120 (a cyanobacterium) were exhaustively studied. The response of the enzyme toward the allosteric activator 3-phosphoglycerate (3PGA) occurs with ultrasensitivity as a consequence of the cross-talk with the inhibitor Pi. Molecular ‘crowding’renders AGPase more sensitive to the interplay between the allosteric regulators and, consequently, enhances the ultrasensitive response. In crowded media, and when orthophosphate is present, the activation kinetics of the enzyme with 3PGA proceed with increased co-operativity and reduced affinity toward the activator. Under conditions of ultrasensitivity, the enzyme's maximal activation takes place in a narrow range of 3PGA concentrations. Moreover, saturation kinetics of the enzyme with respect to its substrates, glucose 1-phosphate and ATP, were different at low or high 3PGA levels in crowded media. Only under the latter conditions did AGPase exhibit discrimination between low or high levels of the activator, which increased the affinity toward the substrates and the maximal activity reached by the enzyme. Studies of fluorescence emission of tryptophan residues, fourth-derivative spectroscopy and size-exclusion chromatography indicated that the ultrasensitive behaviour is correlated with intramolecular conformational changes induced in the tertiary structure of the homotetrameric enzyme. The results suggest a physiological relevance of the ultrasensitive response of AGPase in vivo, since the enzyme could be subtly sensing changes in the levels of allosteric regulators and substrates, and thus determining the flux of metabolites toward synthesis of storage polysaccharides.

scholarly journals Homogeneous Distribution of Polymerizable Coumarin Dyes for Active Few Mode POF

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1975
Author(s):  
Florian Jakobs ◽  
Kristoffer Harms ◽  
Jana Kielhorn ◽  
Daniel Zaremba ◽  
Pen Yiao Ang ◽  
...  
Keyword(s):  
Methyl Methacrylate ◽  
Optical Fibers ◽  
High Performance ◽  
Polymer Chains ◽  
Size Exclusion ◽  
Polymerization Process ◽  
Homogeneous Distribution ◽  
Exclusion Chromatography ◽  
Polymer Optical Fibers ◽  
Coumarin Dyes

For most kinds of active polymer optical fibers, a homogeneous distribution of dye molecules over the entire fiber length and cross section is required. In this study, chemical bonding of dyes to poly(methyl methacrylate) (PMMA) by copolymerization is achieved within the polymerization process instead of dissolving the dyes in the monomers. In combination with an improved fabrication mechanism, this leads to homogeneous dye distribution within the preforms. A method for proving the integration of the dyes into the polymer chains has been developed using high-performance liquid chromatography (HPLC) and size exclusion chromatography (SEC). Prestructured core-cladding preforms with dye-doped poly(cylohexyl methacrylate-co-methyl methacrylate)-core have been prepared with the Teflon string technique and were heat-drawn to few mode fibers.

scholarly journals Human Tyrosinase: Temperature-Dependent Kinetics of Oxidase Activity

2020 ◽  
Vol 21 (3) ◽  
pp. 895 ◽  
Author(s):  
Kenneth L. Young ◽  
Claudia Kassouf ◽  
Monika B. Dolinska ◽  
David Eric Anderson ◽  
Yuri V. Sergeev
Keyword(s):  
Driving Forces ◽  
Autosomal Recessive Disorder ◽  
Oculocutaneous Albinism ◽  
Binding Activity ◽  
Size Exclusion ◽  
Temperature Dependent ◽  
Exclusion Chromatography ◽  
Pigment Biosynthesis ◽  
Kinetics Of ◽  
Human Tyrosinase

Human tyrosinase (Tyr) is involved in pigment biosynthesis, where mutations in its corresponding gene TYR have been linked to oculocutaneous albinism 1, an autosomal recessive disorder. Although the enzymatic capabilities of Tyr have been well-characterized, the thermodynamic driving forces underlying melanogenesis remain unknown. Here, we analyze protein binding using the diphenol oxidase behavior of Tyr and van ’t Hoff temperature-dependent analysis. Recombinant Tyr was expressed and purified using a combination of affinity and size-exclusion chromatography. Michaelis-Menten constants were measured spectrophotometrically from diphenol oxidase reactions of Tyr, using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, at temperatures: 25, 31, 37, and 43 °C. Under the same conditions, the Tyr structure and the L-DOPA binding activity were simulated using 3 ns molecular dynamics and docking. The thermal Michaelis-Menten kinetics data were subjected to the van ‘t Hoff analysis and fitted with the computational model. The temperature-dependent analysis suggests that the association of L-DOPA with Tyr is a spontaneous enthalpy-driven reaction, which becomes unfavorable at the final step of dopachrome formation.

scholarly journals Two-dimensional chromatography of complex polymers. 3. Full analysis of polystyrene-poly(methyl methacrylate) diblock copolymers

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Harald Pasch ◽  
Kibret Mequanint ◽  
Adrian Jörg
Keyword(s):  
Block Copolymers ◽  
Methyl Methacrylate ◽  
Diblock Copolymers ◽  
Size Exclusion ◽  
Molecular Heterogeneity ◽  
Two Dimensional ◽  
Poly Methyl Methacrylate ◽  
Mass Distributions ◽  
Exclusion Chromatography ◽  
Complex Polymers

AbstractPoly(styrene-block-methyl methacrylate)s were fully analyzed by liquid chromatography at the critical point of adsorption (LC-CC) and two-dimensional chromatography. Operating at chromatographic conditions corresponding to the critical points of the homopolymers polystyrene and poly(methyl methacrylate), the block lengths distributions for the different blocks of the block copolymers were determined quantitatively. Information on the amounts and molar mass distributions of homopolymers and coupling products that were identified in the samples as by-products was obtained by on-line coupled 2D chromatography. It was shown that a complete picture of the molecular heterogeneity of block copolymers can be obtained only when information from different chromatographic experiments is combined. Size exclusion chromatography alone is inappropriate for evaluating the molecular heterogeneity of such samples.

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