A Novel Method for the Synthesis of Amphiphilic Copolymer: PHEMA-b-PDMS-b-PHEMA

2014 ◽  
Vol 789 ◽  
pp. 230-234 ◽  
Author(s):  
Jian Feng Xu ◽  
Xiao Quan Peng ◽  
Chun Ju He
Keyword(s):  
Molecular Weight ◽  
Triblock Copolymer ◽  
Reaction System ◽  
Amphiphilic Copolymer ◽  
Good Thermal Stability ◽  
First Order ◽  
H Nmr ◽  
First Order Kinetics ◽  
Novel Method ◽  
Thermal Stability Of

In this study, a novel amphiphilic copolymer based on the flexible polydimethylsiloxane (PDMS) macroinitiator was successfully prepared by atom transfer radical polymerization (ATRP). First, the high molecular weight bis (hydroxyalkyl)-terminated PDMS was prepared by hydrosilation reaction between hydrogen-terminated PDMS and 2-allyloxyethanol in the presence of Karstedt’s catalyst. The macroinitiator Br-PDMS-Br was prepared by the reaction between different molecular weight bis (hydroxyalkyl)-terminated PDMS and 2-bromoisobutyry bromide. Then the amphiphilic ABA-type block copolymers of poly [dimethylsiloxane-b-(hydroxylethyl methacrylate)] were initiated by bromide end-capped PDMS with HEMA, under an appropriate catalyst/ligand system of CuCl/bpy. The polymerization proceeded with first-order kinetics. It showed that the reaction system was a controlled/‘living’ polymerization. The triblock copolymers were characterized by FTIR, 1H-NMR, TGA and GPC techniques. GPC results showed the tribolck copolymer had narrow polydispersity of Mw/Mn (PDI<1.5). TGA results showed the good thermal stability of the triblock copolymer.

Chelating agents in high temperature aqueous chemistry. 1. The kinetics of the thermal decomposition of aqueous nitrilotriacetate (NTA), iminodiacetate (IDA), and N-methyliminodiacetate (MIDA)

1977 ◽  
Vol 55 (10) ◽  
pp. 1762-1769 ◽  
Author(s):  
Meindert Booy ◽  
Thomas Wilson Swaddle
Keyword(s):  
Chelating Agents ◽  
Nuclear Reactors ◽  
Rate Coefficients ◽  
Aqueous Mixtures ◽  
Hydrothermal Conditions ◽  
Good Thermal Stability ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of ◽  
Thermal Stability Of

Aqueous H3NTA, H2MIDA, H2IDA, and their anions decompose under hydrothermal conditions (400–580 K) according to first order kinetics by successive decarboxylations, oxidation by O2 being unimportant except at the highest temperatures. In the presence of added H+, the species H4NTA+ and, to a lesser extent, H3MIDA+ (but not H3IDA+), provide significant decomposition pathways through elimination of a —CH2COO— group (deacetylation). For HnNTA(3−n)−, first order rate coefficients kn for decomposition are k0 = 4.5 × 10−7, k1 ∼ 1 × 10−6, k2 ∼ 7 × 10−5, k3 = 2.1 × 10−4, and k4 = 1.0 × 10−2 s1, at 503 K and ionic strength 2.0 m, the spread in rates being due to differences in ΔS* rather than ΔH*. H2MIDA and H2IDA are comparable in reactivity to H3NTA, while their anions are much less reactive than the NTA species of the same charge. The good thermal stability of aqueous NTA commends it as a reagent for boiler servicing and for decontamination of water-cooled nuclear reactors. A potentiometric method for the estimation of mono-, di-, and tribasic aminoacids in aqueous mixtures of these is described.

Functional Chain Transfer Agent and its Application in Block Polymer Synthesis

2015 ◽  
Vol 799-800 ◽  
pp. 475-478
Author(s):  
Xiao Quan Peng ◽  
Chun Ju He
Keyword(s):  
Block Copolymer ◽  
Triblock Copolymer ◽  
Chain Transfer ◽  
Phase Transfer ◽  
Triblock Copolymers ◽  
Reaction System ◽  
Block Polymer ◽  
First Order ◽  
First Order Kinetics ◽  
Raft Agent

In this report, s-1-dodecyl-s’-(α,α’-dimethyl-α’’-dimethyl-α’’-aceticacid) trithiocarbonate (RAFT-COOH) was successfully synthesized by phase transfer catalyst reaction, which was then amidated with diaminopropyl terminated polydimethylsiloxane (NH2-PDMS-NH2) to synthesize PDMS-based macro-RAFT agent to control the synthesis of tri-block copolymer PDMA-b-PDMS-b-PDMA. The successful synthesis of small and macro chain transfer has been confirmed by techniques of FTIR. Moreover, the polymerization to synthesize tri-block copolymer proceeded with first-order kinetics, which showed the reaction system was a controlled/‘living’ polymerization. The triblock copolymers have also been characterized by FTIR, 1HNMR, and GPC techniques, which confirmed the successful synthesis of triblock copolymer.

Synthesis and Application of a Novel Intumescent Flame Retardant Containing Ferrocenyl

2014 ◽  
Vol 1033-1034 ◽  
pp. 931-936
Author(s):  
Cong Yan Chen ◽  
Rui Lan Fan ◽  
Guan Qun Yun
Keyword(s):  
Thermal Stability ◽  
Flame Retardant ◽  
Flame Retardants ◽  
Intumescent Flame Retardant ◽  
Limiting Oxygen Index ◽  
Good Thermal Stability ◽  
H Nmr ◽  
Positive Effect ◽  
Thermal Stability Of ◽  
Phosphate Groups

A novel intumescent flame retardant (IFR) containing ferrocene and caged bicyclic phosphate groups, 1-oxo-4-[4'-(ferrocene carboxylic acid phenyl ester)] amide-2, 6, 7-trioxa-1-phosphabicyclo- [2.2.2] octane (PFAM), was successfully synthesized. The synthesized PFAM were added to flammable polyurethane (PU) as flame retardants and smoke suppressants. The structure of PFAM was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR) and elemental analysis. Thermal stability of PFAM was tested by themogravimetric analysis (TGA). The results revealed that PFAM had good thermal stability and high char weight, the char weight up to 54% at 600 °C. Flammability properties of PU/PFAM composites were investigated by limiting oxygen index (LOI) test and UL-94 test, respectively. The results of LOI tests showed that the addition of PFAM enhanced flame retardancy of PU. When the content of PFAM reaches to 3%, the LOI value is 22.2. The morphologies of the char for PU and PU/3% PFAM composite can be obtained after LOI testing were examined by SEM. The results demonstrated that PFAM could promote to form the compact and dense intumescent char layer. Experiments showed that, the PFAM application of polyurethane showed positive effect.

scholarly journals Estudios fotoquímicos y electroquímicos de complejos lantánidos de 6-(hidroximetil)piridin- 2-carboxaldehído[2- metilpirimidina-4,6-diil] bishidrazona

2015 ◽  
Vol 43 (1) ◽  
pp. 5-11 ◽  
Author(s):  
María Alejandra Fernandez ◽  
Juan Camilo Barona ◽  
Dorian Polo-Cerón ◽  
Manuel N. Chaur
Keyword(s):  
Uv Light ◽  
Condensation Reaction ◽  
Quantum Yields ◽  
Consecutive Reaction ◽  
Metal Centers ◽  
First Order ◽  
Fluorescence Quantum Yields ◽  
H Nmr ◽  
First Order Kinetics ◽  
Uv Light Irradiation

<p>Herein we report the synthesis of the 6-(hydroxymethyl)pyridine-2- carboxaldehyde[2-methyl-pyrimidine- 4,6-diyl]bis-hydrazone by a condensation reaction between 6-(hydroxymethyl) picolinaldehyde with 4,6-(bis-hydrazino)-2- methylpyrimidine. This bis-hydrazone can be visualized as a two-arm system which exhibits photochemical induced [E,E]/[E,Z]/[Z,Z’] isomerizations and double coordination to metal centers. Configurational changes, upon UV light irradiation, were followed over time by 1 H NMR, establishing that isomerization, in both arms, is a consecutive reaction that follows first-order kinetics (k1 = 4.06 x 10-4 s-1 and k2 = 2.80 x 10-4 s-1). Furthermore, the synthesis of bis-hydrazone metal complexes with La (III) and Sm (III) ions was achieved; subsequently, the absorption and emission properties of these complexes were studied, determining the fluorescence quantum yields, 𝟇La= 0.2024 and 𝟇Sm= 0.1413. Electrochemical studies of the complexes were conducted by square wave voltammetry, demonstrating that the bis-hydrazone and its complexes are electroactive species between +1.5 and -2.5 V.</p>

scholarly journals Thermally Stable Forms of Pure Polyaniline Catalyzed by an Acid-Exchanged Montmorillonite Clay Called Maghnite- as an Effective Catalyst

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Rahmouni Abdelkader ◽  
Harrane Amine ◽  
Belbachir Mohammed
Keyword(s):  
Oxidative Polymerization ◽  
Montmorillonite Clay ◽  
Scanning Calorimetry ◽  
Good Thermal Stability ◽  
Effective Catalyst ◽  
H Nmr ◽  
Western Algeria ◽  
Local Company ◽  
Stable Forms ◽  
Thermal Stability Of

Polyaniline salt form (PANI-ES) was synthesized by oxidative polymerization of aniline using potassium persulfate as an oxidant and an acid-exchanged montmorillonite clay called Maghnite-H+as an effective catalyst. The clay, which was used as a catalyst, was supplied by a local company known as ENOF Maghnia (Western Algeria). The chemical stability of PANI has been investigated by thermogravimetry and differential scanning calorimetry, that a good thermal stability of PANI could be improved by combining PANI with montmorillonite. TGA results illustrated that there were two major stages for weight loss of the ES-form PANI powder sample. The different forms of PANI were characterized by infrared spectroscopy, thermal analysis, and H-NMR spectroscopy and conductivity measurements.

A Human Pharmacological Study Comparing Conventional Heparin and a Low Molecular Weight Heparin Fragment

1985 ◽  
Vol 53 (02) ◽  
pp. 208-211 ◽  
Author(s):  
G Bratt ◽  
E Törnebohm ◽  
D Lockner ◽  
G Bergströ
Keyword(s):  
Molecular Weight ◽  
Half Life ◽  
Low Molecular Weight Heparin ◽  
Pharmacological Study ◽  
Low Molecular Weight ◽  
Dose Dependency ◽  
First Order ◽  
First Order Kinetics ◽  
Heparin Activity ◽  
Different Doses

SummaryThe pharmacokinetics of a heparin fragment of low molecular weight (LMWH) of 4000-5000 D and unfractioned standard heparin (UFH) have been studied after i. v. injections of different doses and infusions in 8 humans.The heparin activity was significantly higher and the effect on APTT lower after LMWH fragment as compared to UFH in the same doses.The half-life of heparin activity was about 1 hr for UFH and about 2 hr for LMWH. LMWH was found to be eliminated according to first order kinetics and there were no signs of dose dependency.

Copolymerization of 5-norbornene-2-metheneoxy-trimethylsilyl with methyl 5-norbornene-2-carboxylate catalyzed by a novel Ni(benzocyclohexan-ketonaphthylimino)2/B(C6F5)3) system

2012 ◽  
Vol 32 (6-7) ◽  
pp. 415-423
Author(s):  
Xiaofeng Wang ◽  
Xiaohui He ◽  
Defu Chen ◽  
Yiwang Chen
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Nmr Spectra ◽  
Catalyst System ◽  
Narrow Molecular Weight Distribution ◽  
Complex Catalyst ◽  
Good Thermal Stability ◽  
H Nmr ◽  
Catalyst Systems ◽  
C Nmr

Abstract Copolymerization of 5-norbornene-2-metheneoxy-trimethylsilyl [NB-CH2OSi(CH3)3] with norbornene (NB) or methyl 5-norbornene-2-carboxylate (NB-COOCH3) was carried out in toluene by using novel nickel(II) complex catalyst systems, Ni(benzocyclohexan-ketonaphthylimino)2/B(C6F5)3 [Ni(bchkni)2/B(C6F5)3]. The catalyst system showed high activity on the copolymerization of NB-CH2OSi(CH3)3 with NB (2.3–3.3×104 gpolymer/molNi·h) and NB-CH2OSi(CH3)3 with NB-COOCH3(0.5–3.0×104 gpolymer/molNi·h). However, the solubility of copolymers of NB-CH2OSi(CH3)3 with NB and NB-CH2OSi(CH3)3 with NB-COOCH3, which contain 18.7–86.7 mol% of NB-CH2OSi(CH3)3, was too poor to characterize. The achieved copolymers were confirmed to be vinyl-addition copolymers through the analysis of FTIR, 1H NMR, and 13C NMR spectra. The incorporation rate was 8.7–86.7 mol% at a content of 10–90 mol% of the NB-CH2OSi(CH3)3 in the monomer feeds ratios. The obtained ester functionalized NB copolymer containing 8.7–18.7 mol% of NB-CH2OSi(CH3)3 showed a moderate molecular weight (Mw=1.6–6.0×104 g/mol) and relative narrow molecular weight distribution (Mw/Mn=1.6–2.2). Thermogravimetry (TGA) analyses results showed that the copolymers exhibited good thermal stability (Td=330–350°C) and were noncrystalline by WAXD analyses results.

scholarly journals Synthesis, Characterization and Copolymerization of N-(phenylamino)maleimide with MMA

2007 ◽  
Vol 4 (2) ◽  
pp. 265-271
Author(s):  
B. L. Hiran ◽  
S. N. Paliwal ◽  
Jyoti Choudhary ◽  
P. R. Choudhary
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Density Measurement ◽  
Gel Permeation Chromatography ◽  
Radical Copolymerization ◽  
Free Radical Copolymerization ◽  
H Nmr ◽  
Gel Permeation ◽  
Ft Ir ◽  
Thermal Stability Of

The free radical copolymerization of N-(phenylamino)maleimide (N-PAMI) was carried. The copolymerization with methyl methacrylate (MMA) was performed at 65°C with AIBN as the initiator in THF solvent. Resulting copolymer was characterized by density measurement, intrinsic viscosity, solubility, FT-IR &1H NMR spectroscopy. Effect of the solvent and time on copolymer yield was also investigated. The molecular weight of copolymer was determined by gel permeation chromatography (GPC). The thermal stability of copolymer was determined by Thermogravimetric analysis (TGA).

Treatment of Bleachery Effluents from Kraft Mills Pulping Mature Eucalypts

1994 ◽  
Vol 29 (5-6) ◽  
pp. 247-258 ◽  
Author(s):  
B. H. Boyden ◽  
X. Z. Li ◽  
T. J. Schulz ◽  
O. Hijazin ◽  
P. Peiris ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Biological Treatment ◽  
Fungal Isolate ◽  
Priority Pollutants ◽  
Tertiary Treatment ◽  
Monod Kinetics ◽  
Cod Reduction ◽  
First Order ◽  
First Order Kinetics

This study concentrated on the biological treatment and post-ozonation of mature eucalypt kraft bleachery effluents. The objectives were to optimise reduction of priority pollutants such as AOX, chlorate, high molecular weight chromophores and toxicity while maintaining high COD/BOD removals. Biological treatment was adequately modelled with Monod kinetics, using biodegradable COD. Sludge yields were of the order 0.76 g biomass/g BCOD. Treatment was most effective (70% total COD reduction and 95% BOD5 reduction) with sludge ages over 20 days and F/M ratios 0.2-0.3. Biological treatment did not reduce total AOX nor colour but reduced chlorate by 63% in preliminary trials. A fungal isolate, Aspergillus.p2 reduced colour by 54% when supplemented with glucose. Ozonation as a tertiary treatment reduced AOX by 60% and colour decrease followed first-order kinetics with respect to ozone consumption.

A New Approach in Kinetic Modeling Using Thermodynamic Framework for Chemically Reacting Systems and Oxidative Ageing in Polymer Composites

2013 ◽  
Author(s):  
K. V. Mohankumar ◽  
K. Kannan
Keyword(s):  
Polymer Composites ◽  
Reaction System ◽  
Gibbs Potential ◽  
New Approach ◽  
First Order ◽  
First Order Kinetics ◽  
Chemically Reacting Systems ◽  
Chemically Reacting ◽  
Reacting Systems ◽  
Single Reaction

A thermodynamic framework for chemically reacting systems is put to use in kinetic modeling of any chemical system with N species undergoing M reactions. A new approach of deriving kinetic models from a Gibbs potential, of multivariate polynomial function, is demonstrated with an example of single reaction system involving three species. Also, the usual first order kinetics is deduced as a special case in the example. The distinct advantages of the new approach lies in obtaining the evolution of concentrations of species, their individual chemical potentials and the specific Gibbs potential and is demonstrated for a single reaction system as an example. Oxidation in polymer composites is studied with a coupled reaction-diffusion model obtained using first order kinetics and is solved for a boundary value problem that predicts the concentration of species over space and time. Concentration of oxidized products is correlated with modulus of aged sample and degradation effects is calculated in case of simple torsion.

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