Changes in Molecular Weight of Poly(Styrenesulfonate) Initiated by Thioxanthone: Photolysis and Photo-Oxidation

2016 ◽  
Vol 869 ◽  
pp. 346-349
Author(s):  
Josy Anteveli Osajima ◽  
Carla Cristina Schmitt Cavalheiro ◽  
Miguel Guillermo Neumann
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Main Chain ◽  
Inert Atmosphere ◽  
Kinetic Behavior ◽  
Photo Oxidation ◽  
Polymer Main Chain ◽  
Air Atmosphere ◽  
Atmosphere System ◽  
Kinetics Of

The presence of dyes in colored polymers can cause a series of reactions that promote their photodegradation under irradiation. The aim of this study was to investigate the kinetic behavior of the photodegradation of poly (sodium 4-styrenesulfonate) (PSS) in aqueous solution or in the presence of thioxanthone (TX) under UV radiation in different atmospheres. These systems were monitored by SEC. The polydispersity decreased in all systems studied indicating that there was a breach of the polymer main chain. Only the PSS / TX / air atmosphere system peaked, which occured at 43h of irradiation. However, this system showed slower kinetics of polymeric scission due to the dye suppressing a transfer of energy from the triplet state to the polymer. The photodegradation of solutions of PSS / air atmosphere showed higher efficiency under ultraviolet radiation in relation to the PSS in the presence or absence of the dye under an inert atmosphere.

scholarly journals [Rh(L-alaninate)(1,5-Cyclooctadiene)] Catalyzed Helix-Sense-Selective Polymerizations of Achiral Phenylacetylenes

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1223 ◽  
Author(s):  
Qingyu Wang ◽  
Hongge Jia ◽  
Yongqiang Shi ◽  
Liqun Ma ◽  
Guoxing Yang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Main Chain ◽  
Helical Structure ◽  
Active Species ◽  
Rhodium Complex ◽  
High Yield ◽  
Hydroxyl Groups ◽  
High Catalytic Activity ◽  
Chiral Amine ◽  
Polymer Main Chain

The [Rh(L-alaninate)(cod)] (cod = 1,5-Cyclooctadiene) complex was synthesized and characterized. Asymmetric polymerizations of achiral phenylacetylene with two hydroxyl groups and a dodecyl group (DoDHPA) were performed by using the rhodium complex as the catalyst to provide polymers with a higher molecular weight (>105) than the polymers obtained using the [Rh(cod)Cl]2 initiator systems. The resulting polymers showed circular dichroism (CD) signals at approximately 310 and 470 nm, indicating that they have a preferential one-handed helical structure. The helix sense in the polymer main chain was controlled by the sign of the catalyst chirality. These findings suggest that the rhodium complex with a chiral amine is the true active species for the helix-sense-selective polymerization of DoDHPA. The [Rh(L-alaninate)(cod)] complex also exhibits high catalytic activity in the polymerization of phenylacetylene (PA) to give a high yield and molecular weight. All these results demonstrate that this Rh complex is an excellent catalyst for the polymerization of phenylacetylene monomers.

Poly(para-phenylene) ionomer membranes: effect of methyl and trifluoromethyl substituents

2021 ◽  
Author(s):  
Fanghua Liu ◽  
Jinju Ann ◽  
Junpei Miyake ◽  
Kenji Miyatake
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Main Chain ◽  
Polymer Main Chain ◽  
Ionomer Membranes ◽  
Sulfonated Poly

Sulfonated poly(para-phenylene)s with high molecular weight and membrane forming capability were obtained by use of the effect of methyl and trifluoromethyl substituents. The linearity of the polymer main chain decreased...

scholarly journals Fragmentation of Chitosan by Acids

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Mohammad Reza Kasaai ◽  
Joseph Arul ◽  
Gérard Charlet
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Kinetic Data ◽  
Chemical Structure ◽  
Size Exclusion ◽  
Experimental Conditions ◽  
First Order ◽  
H Nmr ◽  
Exclusion Chromatography ◽  
Kinetics Of

Fragmentation of chitosan in aqueous solution by hydrochloric acid was investigated. The kinetics of fragmentation, the number of chain scissions, and polydispersity of the fragments were followed by viscometry and size exclusion chromatography. The chemical structure and the degree of N-acetylation (DA) of the original chitosan and its fragments were examined by1H NMR spectroscopy and elemental analysis. The kinetic data indicates that the reaction was of first order. The results of polydispersity and the DA suggest that the selected experimental conditions (temperature and concentration of acid) were appropriate to obtain the fragments having the polydispersity and the DA similar to or slightly different from those of the original one. A procedure to estimate molecular weight of fragments as well as the number of chain scissions of the fragments under the experimental conditions was also proposed.

Kinetics and mechanism of the reaction of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione

1990 ◽  
Vol 55 (8) ◽  
pp. 1984-1990 ◽  
Author(s):  
José M. Hernando ◽  
Olimpio Montero ◽  
Carlos Blanco
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Activation Parameters ◽  
Enol Form ◽  
Kinetics And Mechanism ◽  
Kinetic Constants ◽  
Steric Factors ◽  
Kinetics Of ◽  
Mechanism Of The Reaction

The kinetics of the reactions of iron(III) with 6-methyl-2,4-heptanedione and 3,5-heptanedione to form the corresponding monocomplexes have been studied spectrophotometrically in the range 5 °C to 16 °C at I 25 mol l-1 in aqueous solution. In the proposed mechanism for the two complexes, the enol form reacts with the metal ion by parallel acid-independent and inverse-acid paths. The kinetic constants for both pathways have been calculated at five temperatures. Activation parameters have also been calculated. The results are consistent with an associative activation for Fe(H2O)63+ and dissociative activation for Fe(H2O)5(OH)2+. The differences in the results for the complexes of heptanediones studied are interpreted in terms of steric factors.

Temperature Effect on the Two-Dimensional Phase Transition Kinetics of Adenine Adsorbed at the Hg Electrode/Aqueous Solution Interface

2003 ◽  
Vol 68 (8) ◽  
pp. 1407-1419 ◽  
Author(s):  
Claudio Fontanesi ◽  
Roberto Andreoli ◽  
Luca Benedetti ◽  
Roberto Giovanardi ◽  
Paolo Ferrarini
Keyword(s):  
Phase Transition ◽  
Aqueous Solution ◽  
Phase Change ◽  
Temperature Effect ◽  
Transition Rate ◽  
Effect Of Temperature ◽  
Two Dimensional ◽  
Solution Interface ◽  
Phase Transition Kinetics ◽  
Kinetics Of

The kinetics of the liquid-like → solid-like 2D phase transition of adenine adsorbed at the Hg/aqueous solution interface is studied. Attention is focused on the effect of temperature on the rate of phase change; an increase in temperature is found to cause a decrease of transition rate.

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