scholarly journals Synthesis of Controllable Carboxylated Polystyrene Microspheres by Two-Step Dispersion Polymerization with Hydrocarbon Alcohols

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Bin Zhang ◽  
Jiazhen Lu ◽  
Xin Liu ◽  
Haibo Jin ◽  
Guangxiang He ◽  
...  
Keyword(s):  
Reaction Time ◽  
Dispersion Polymerization ◽  
Great Influence ◽  
Gel Permeation Chromatography ◽  
Polystyrene Microspheres ◽  
Carboxyl Content ◽  
Solvent Type ◽  
Gel Permeation ◽  
Carboxyl Group Content ◽  
Hydrocarbon Alcohols

Carboxylated polystyrene (PS) microspheres were synthesized by the two-step dispersion polymerization of styrene in hydrocarbon alcohols (CnH2n+1OH,n=1–5) in the presence of acrylic acid (AA) as a functional comonomer, 2,2′-azobis-(2-methylbutyronitrile) (AMBN) as the initiator and polyvinylpyrrolidone (PVP55) as the dispersant. The effects of solvent type, AA concentration, and first reaction time on the carboxyl content on the microsphere surfaces were investigated. The PS microspheres were characterized by scanning electron microscopy, infrared spectroscopy, nuclear magnetic resonance, and gel permeation chromatography. The results showed that the first reaction time of the two-stage dispersion polymerization had a great influence on the nucleation process, and appropriately prolonging the first-step reaction time had a great influence on the surface carboxyl content. The effect of the solvent on the surface carboxyl content of PS microspheres was significant. With n-butanol as the solvent, the carboxyl group content on the surface of the microspheres reached 57.05 mg/g.

Synthesis for an Amide-Ester Type Polycarboxylate Superplasticizer and its Application in Concrete

2014 ◽  
Vol 989-994 ◽  
pp. 233-237
Author(s):  
Chong Sun ◽  
Guang Jun Zheng ◽  
Yao Bi ◽  
Hui Zhou
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
Cement Mortar ◽  
Concrete Strength ◽  
Gel Permeation Chromatography ◽  
Step Method ◽  
Application Performance ◽  
Polycarboxylate Superplasticizer ◽  
Gel Permeation ◽  
New Type

A new type of amide-modified polycarboxylate superplasticizer was synthesized by a two-step method: Firstly, a mixture of amidated and esterified products reacted by maleic anhydride and 2-aminoethanol was modified through Mannich reaction. Then, the modified product was reacted with Prenyl alcohol polyethenoxy ether (TPEG), acrylic acid and other monomers to obtain an amide-structured polycarboxylate superplasticizer. The molecular weight and molecular weight distribution were measured by Gel permeation chromatography (GPC). Lastly, the optimum AA to modified product ratio, initiator dosage and reaction time were determined by cement mortar test. The concrete application performance showed that the synthesized superplasticizer could improve the fluidity of the concrete and maintain the slump loss as well. The introduction of modified PCE has no harm for the concrete strength.

Molecular Weight and its Distribution of PET Depolymerization Residue under Microwave Irradiation

2014 ◽  
Vol 997 ◽  
pp. 371-374
Author(s):  
Cheng Cai Zeng ◽  
Qing Hua Tang ◽  
Ling Zhong ◽  
Zhi De Liu ◽  
Dong Zhang
Keyword(s):  
Molecular Weight ◽  
Reaction Time ◽  
Microwave Irradiation ◽  
Gel Permeation Chromatography ◽  
Molecular Chain ◽  
Gel Permeation

The molecular chain of PET would be broken in the process of depolymerization reactions under microwave irradiation, which would lead to changes in molecular weight. In this paper, the molecular weight of PET residue measured by gel permeation chromatography (GPC) was used to track the progress of PET depolymerization. The results showed that the molecular weight of the residue after depolymerization under 180°Cdecreases as reaction time increases, however when the temperature of depolymerization was 190°Cor 200°C, with the reaction time increases, the molecular weight of residue decreased first and then increased slightly.

Study on Esterification Characteristics of TEMPO-Oxidized Cellulose

2013 ◽  
Vol 749 ◽  
pp. 49-53
Author(s):  
Ai Min Tang ◽  
Kai Wang
Keyword(s):  
Reaction Time ◽  
Acetic Anhydride ◽  
Reaction Temperature ◽  
Influence Factors ◽  
Great Influence ◽  
Functional Materials ◽  
Acid Group ◽  
Oxidized Cellulose ◽  
Carboxyl Content ◽  
Acetyl Group

Oxidized cellulose acetate (OCA) with carboxylic acid group on C-6 position of glucose is a kind of biodegradable functional materials which can be dissolved in organic solvents. First, cellulose was oxidized with TEMPO (2, 2, 6, 6-tetramethyl-piperidyl-1-oxyl) oxidation system, and then OCA was produced via esterification by reacting the oxidized cellulose with acetic anhydride. The influence factors such as carboxylic content of oxidized cellulose, reaction temperature, reaction time, and concentration of acetic anhydride on degree of substitution (DS) of acetyl group and intrinsic viscosity ([η]) of OCA were investigated. The result revealed that the DS of acetyl group can be increased effectively from 2.61 to 2.74 by increasing reaction temperature from 50°C to 80°C, and from 2.58 to 2.72 by prolonging reaction time from 40min to 180min, but the [η] of the product decreased at the same time. An increase in concentration of acetic anhydride led to an increase in DS and [η] of OCA. As the carboxyl content increased from 0.383 mmol/g to 0.797 mmol/g, the DS of acetyl group decreased from 2.81 to 2.73. That result revealed the carboxyl content also has a great influence on the esterification characteristics.

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

1996 ◽  
Vol 75 (02) ◽  
pp. 326-331 ◽  
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.

Gel Permeation Chromatography of Polyelectrolytes

1981 ◽  
Vol 4 (8) ◽  
pp. 1297-1309 ◽  
Author(s):  
M. Rinaudo ◽  
J. Desbrières ◽  
C. Rochas
Keyword(s):  
Gel Permeation Chromatography ◽  
Gel Permeation

scholarly journals Low-Temperature Mineralisation of Titania-Siloxane Composite Layers

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 50
Author(s):  
Tomáš Svoboda ◽  
Michal Veselý ◽  
Radim Bartoš ◽  
Tomáš Homola ◽  
Petr Dzik
Keyword(s):  
Low Temperature ◽  
Great Influence ◽  
Gel Permeation Chromatography ◽  
Photocatalytic Decomposition ◽  
Acid Orange 7 ◽  
Composite Layers ◽  
Nonthermal Treatment ◽  
Plasma Methods ◽  
Voltammetric Measurements ◽  
Thermally Treated

This paper deals with low-temperature mineralisation of coatings made with titania-siloxane compositions (TSC). Methyltriethoxysilane has been adopted as the precursor for the siloxane, and during its synthesis, an oligomeric siloxane condensate with methyl moieties acting as TiO2 binder has been produced. These methyl moieties, contained in TSC, provide solubility and prevent gelling, but reduce the hydrophilicity of the system, reduce the transfer of electrons and holes generated in the TiO2. In order to avoid these unfavourable effects, TSC mineralisation can be achieved by nonthermal treatment, for example, by using UV-radiation or plasma treatment. Characterisation of the siloxane was performed by gel permeation chromatography (GPC), which showed the size of the siloxane chain. Thermogravimetric analysis revealed a temperature at which the siloxane mineralises to SiO2. Printed layers of two types of TSC with different siloxane contents were studied by a scanning electron microscope (SEM), where a difference in the porosity of the samples was observed. TSC on fluorine-doped tin oxide (FTO) coated glass and microscopic glass were treated with non-thermal UV and plasma methods. TSC on FTO glass were tested by voltammetric measurements, which showed that the non-thermally treated layers have better properties and the amount of siloxane in the TSC has a great influence on their efficiency. Samples on microscopic glass were subjected to a photocatalytic decomposition test of the model pollutant Acid orange 7 (AO7). Non-thermally treated samples show higher photocatalytic activity than the raw sample.

Sign in / Sign up

Export Citation Format

Share Document