scholarly journals Effect of Multivalent Cations on Intermolecular Association of Isotactic and Atactic Poly(Methacrylic Acid) Chains in Aqueous Solutions

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 605 ◽  
Author(s):  
Patricija Hriberšek ◽  
Ksenija Kogej
Keyword(s):  
Aqueous Solutions ◽  
Methacrylic Acid ◽  
Shape Parameter ◽  
The Other ◽  
Carboxyl Groups ◽  
Carboxylate Groups ◽  
Intermolecular Association ◽  
Core Shell Structure ◽  
Cooperative Hydrogen Bonding ◽  
Aggregate Structures

The formation of nanoparticles of two poly(methacrylic acid) (PMA) isomers, atactic (aPMA) and isotactic (iPMA), was investigated in aqueous solutions in the presence of mono- (Na+) and multivalent cations (Mg2+ and La3+). Using dynamic (DLS) and static light scattering (SLS), we show that PMA nanoparticles have characteristics of microgel-like particles with a denser core and a swollen corona. iPMA aggregates are stable at a much higher degree of neutralization (αN) than the aPMA ones, indicating a much stronger association between iPMA chains. This is explained by proposing segregation of ionized and unionized carboxyl groups within the iPMA aggregates and subsequent cooperative hydrogen-bonding between COOH groups. The calculated shape parameter (ρ) suggests different behavior of both isomers in the presence of Mg2+ ions on one hand and Na+ and La3+ on the other. The microgel-like particles formed in the presence of Mg2+ ions have a more even mass distribution (possibly a no core-shell structure) in comparison with those in the presence of Na+ and La3+ ions. Differences between the aggregate structures in the presence of different ions are reflected also in calorimetric experiments and supported by pH and fluorimetric measurements. Reasons for different behavior in the presence of Mg2+ ions lie in specific properties of this cation, in particular in its strong hydration and preference towards monodentate binding to carboxylate groups.

Disinfection of Fruits with Activated Water

2019 ◽  
Vol 10 ◽  
pp. 1864-1872
Author(s):  
Prof. Teodora P. Popova
Keyword(s):  
Antimicrobial Activity ◽  
Aqueous Solutions ◽  
Antimicrobial Properties ◽  
The Other ◽  
Gram Negative Bacteria ◽  
High Antimicrobial Activity ◽  
Gram Negative ◽  
E Coli ◽  
Number Of Microorganisms ◽  
Lower Effect

The effect of ionized aqueous solutions (anolytes and catholyte) in the processing of fruits (cherries, morellos, and strawberries) for decontamination has been tested. Freshly prepared analytes and catholyte without the addition of salts were used, as well as stored for 7 months anolytes, prepared with 0.5% NaCl and a combination of 0.5% NaCl and 0.5% Na2CO3. The anolyte prepared with a combination of 0.5% NaCl and 0.5% Na2CO3, as well as the anolyte obtained with 0.5% NaCl, exhibit high antimicrobial activity against the surface microflora of strawberries, cherries, and sour cherries. They inactivate E. coli for 15 minutes. The other species of the fam. Enterobacteriaceae were also affected to the maximum extent, as is the total number of microorganisms, especially in cherries and sour cherries. Even stored for 7 months, they largely retain their antimicrobial properties. Anolyte and catholyte, obtained without the addition of salts, showed a lower effect on the total number of microorganisms, but had a significant effect on Gram-negative bacteria, and especially with regard to the sanitary indicative E. coli.

Binding of lead and copper(II) cations to hemicelluloses of rye bran

1986 ◽  
Vol 51 (10) ◽  
pp. 2250-2258 ◽  
Author(s):  
Rudolf Kohn ◽  
Zdena Hromádková ◽  
Anna Ebringerová
Keyword(s):  
Uronic Acid ◽  
Equilibrium Solution ◽  
Glucuronic Acid ◽  
The Other ◽  
Carboxyl Groups ◽  
Stoichiometric Ratio ◽  
Molar Ratios ◽  
Free Ions ◽  
Uronic Acid Content ◽  
The Relationship

Several fractions of acid hemicelluloses isolated from rye bran were characterized by molar ratios of saccharides (D-Xyl, L-Ara, D-Glc, D-Gal) and 4-O-methyl-D-glucuronic acid and protein content. Binding of Pb2+ and Cu2+ ions to these acid polysaccharides was considered according to function (M)b = f([M2+]f), expressing the relationship between the amount of metal (M)b bound to 1 g of the substance and the concentration of free ions [M2+]f in the equilibrium solution and according to the association degree β of these cations with carboxyl groups of uronic acid at a stoichiometric ratio of both components in the system under investigation. Acid hemicelluloses contained only a very small portion of uronic acid ((COOH) 0.05-0.18 mmol g-1); the model polysaccharide, 4-O-methyl-D-glucurono-D-xylan of beech, was substantially richer in uronic acid content ((COOH) 0.73 mmol g-1). Consequently, the amount of lead and copper bound to acid hemicelluloses is very small ((M)b 0.017-0.025 mmol g-1) at [M2+]f = 0.10 mmol l-1. On the other hand, much greater amount of cations ((M)f 0.09-0.10 mmol g-1) was bound to the glucuronoxylan. The association degree β was like with the majority of samples (β = 0.31-0.38). The amount of lead and copper(II) bound to acid hemicelluloses from rye bran is several times lower than that bound to dietary fiber isolated from vegetables (cabbage, carrot), rich in pectic substances.

Study of polymer chain dynamics in solution by time-resolved spectrofluorometry

1989 ◽  
Vol 54 (11) ◽  
pp. 3011-3024 ◽  
Author(s):  
Vlastimil Fidler ◽  
Stefan Vajda ◽  
Zuzana Limpouchová ◽  
Jiří Dvořák ◽  
Karel Procházka ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Conformational Changes ◽  
Methacrylic Acid ◽  
Correlation Time ◽  
General Level ◽  
Polymeric Chain ◽  
Relative Molecular Mass ◽  
Chain Dynamics ◽  
Time Resolved ◽  
Covalently Bonded

The methodology of polarization time-resolved fluorometry and interpretation of its results are outlined at a general level, and the measurement on and use of facilities of the Edinburgh Instruments Model 299T apparatus are discussed in detail. The dynamics of conformational changes in chains of poly(methacrylic acid) containing covalently bonded dansyl labels are studied in aqueous solutions at various pH. It is shown that at pH > 6, the shorter effective rational correlation time τr < 2 ns corresponds to the rotation of the free dansyl label about bonds by which it is attached to the polymeric chain; at pH < 4 the longer effective rational correlation time τr = 20-26 ns corresponds to the rotation of the compact spherical formation constituted by a part of the collapsed polymeric chain in which the label is fixed and whose relative molecular mass is approx. 15 000-20 000.

Structural Organization of Interpolymer Complexes Formed by Poly(N-vinylamides) and Poly(methacrylic acid) Chains Regularly Grafted to Polyimide in Aqueous Solutions

2018 ◽  
Vol 60 (S1) ◽  
pp. 172-178 ◽  
Author(s):  
T. N. Nekrasova ◽  
V. D. Pautov ◽  
T. D. Anan’eva ◽  
T. K. Meleshko ◽  
I. V. Ivanov ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Methacrylic Acid ◽  
Structural Organization ◽  
Interpolymer Complexes

Photografting of methacrylic acid onto HDPE initiated by acetaldehyde in aqueous solutions

2010 ◽  
Vol 119 (2) ◽  
pp. 629-635 ◽  
Author(s):  
Anqi Song ◽  
Di Zhao ◽  
Rong Rong ◽  
Lin Zhang ◽  
Huiliang Wang
Keyword(s):  
Aqueous Solutions ◽  
Methacrylic Acid

Density estimates of binary aqueous solutions

1983 ◽  
Vol 48 (8) ◽  
pp. 2327-2334
Author(s):  
Otakar Söhnel ◽  
Petr Novotný ◽  
Zdeněk Šolc
Keyword(s):  
Aqueous Solutions ◽  
Molar Volume ◽  
Partial Molar Volume ◽  
Infinite Dilution ◽  
The Other ◽  
Density Estimates ◽  
Molar Volumes ◽  
Solutions Of Electrolytes ◽  
Experimental Values

Two methods are given for assessment of density of binary aqueous solutions of electrolytes; one is based on partial molar volume of the dissolved electrolyte at infinite dilution, and the other is based on additivity of apparent molar volumes at a given concentration. The density estimates of aqueous solutions by means of the two methods are compared with experimental values for some electrolytes of the type 1-1 to 4 and 2-2. In all cases the estimates agree with experimental densities up to concentrations of the saturated solutions.

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