Water-soluble copolymers. XLII. Cationic polyelectrolytes of acrylamide and 2-acrylamido-2-methylpropanetrimethylammonium chloride

The new monomer 2-acrylamido-2-methylpropanetrimethylammonium chloride (AMP-TAC, M₂) has been synthesized. Free radical copolymerization with acrylamide (AM, M₁) in feed ratios varying from 10 to 50 mol % AMPTAC gave the cationic ATAM series. Copolymer compositions were determined from ¹³C-NMR. The reactivity ratio product r₁r₂ was found to be 0.62. Molecular weights varied from 1.4 to 16.5 × 10⁶ g/mol for the copolymers. Turbidimetric studies showed aqueous solutions of the copolymers to be phase stable in the presence of CaCl₂ and Na₂CO₃ up to 100°C. Solution behavior was independent of pH in the range of 3 to 11, and temperature in the range of 25 to 60°C. Intrinsic viscosities of the cationic copolymers decreased with the addition of electrolytes; however, some samples showed curvature in plots of intrinsic viscosity versus the inverse square root of ionic strength. © 1993 John Wiley & Sons, Inc.     

水溶性聚合物和两亲聚合物:14.丙烯酰胺/2-丙烯酰胺基十六烷磺酸铵无规共聚物

水溶液中用硫酸亚铁-异丙苯过氧化氢氧化还原引发体系合成了丙烯酰胺(AM)/2-丙烯酰胺基十六烷磺酸铵(AMC_(16)SNH_4)无规共聚物。用元素分析、IR、~(13)C-NMR和~1H-NMR对其进行了表征。对水溶液性质的研究结果表明,与部分水解聚丙烯酰胺相比,这种新型共聚物有着优异的耐盐性、耐温性和贮存稳定性。     

Water-soluble copolymers. XIII. Copolymers of acrylamide with sodium-3-acrylamido-3-methylbutanoate: Solution properties

Dilute solution properties of copolymers of acrylamide (AM) with sodium-3-acrylamido-3-methylbutanoate (NaAMB) of known molecular weight have been studied as a function of composition, temperature, time, pH, and added electrolytes. Phase separation and potentiometric studies have also been performed. The AM–NaAMB copolymers exhibit high solution viscosities, good salt tolerance, and moderate viscosity-temperature coefficients. In addition, these copolymers exhibit no phase separation in the presence of divalent cations as is common with many such carboxylated polyelectrolytes. These properties are due to favorable conformations in solution resulting from microstructure and hydrogen bonding effects.     

Water-soluble copolymers. XII. Copolymers of acrylamide with sodium-3-acrylamido-3-methylbutanoate: Synthesis and characterization

The copolymerization of acrylamide (AM) with sodium-3-acrylamido-3-methylbutanoate (NaAMB) has been studied. The value of r₁r₂ has been determined to be 0.56 for the AM–NaAMB pair. The molecular weights of the copolymers were relatively unaffected by monomer feed ratios. The copolymer microstructures, including run numbers and sequence distributions, were calculated from the reactivity ratios. The solution properties of the AM–NaAMB copolymers, as well as the NaAMB homopolymer, will be reported in a subsequent paper.     

Water-soluble copolymers. X. Copolymers of acrylamide with N-(1,1-dimethyl-3-oxybutyl)acrylamide and N,N-dimethylacrylamide: Solution properties

Dilute solution properties of copolymers of acrylamide (AM) with N-(1,1-dimethyl-3-oxybutyl)acrylamide (DAAM) and with N,N-dimethylacrylamide (DMAM) have been studied as a function of composition, temperature, time, and added electrolytes sodium chloride and calcium chloride. Unlike the AM-DMAM copolymers, the AM-DAAM copolymers show solution viscosity increases in the presence of added NaCl and CaCl₂ and decreases with increasing temperature which are related to copolymer composition. The unusual viscosity behavior of the DAAM-AM copolymers is suspected to be due to chain extension resulting from intramolecular hydrogen bonding and other cooperative associations along the macromolecular backbone.     

Water-soluble copolymers. IX. Copolymers of acrylamide with N-(1,1-dimethyl-3-oxybutyl)acrylamide and N,N-dimethylacrylamide: Synthesis and characterization

The copolymerizations of acrylamide (AM) with N-(1,1-dimethyl-3-oxybutyl)acrylamide (DAAM) and with N,N-dimethylacrylamide (DMAM) have been studied. The values of r₁,r₂ have been determined to be 0.75 for the AM-DAAM pair and 0.86 for the AM-DMAM pair. The molecular weights of the copolymers were found to decrease with an increase in the feed composition of DAAM or DMAM. The microstructure was predicted for a wide range of feed compositions through a knowledge of reactivity ratios. These model structures are utilized for assessment of structure/dilute solution relationships reported in a subsequent paper in this series.     

Water-soluble copolymers. VII. Cerium (IV) induced graft copolymerization of acrylamide and sodium-2-acrylamido-2-methylpropane sulfonate onto dextran

Studies were conducted on grafting of acrylamide (AM) and sodium-2-acrylamido-2-methylpropane sulfonate (NaAMPS) comonomers onto dextran utilizing Ce(IV) induced initiation. The effects of reaction temperature, the Ce(IV)/dextran ratio, and the AM/NaAMPS ratio on grafting yield were investigated. The graft copolymerization behavior can be explained by exchange of the AMPS anion with one of the ligands on the Ce(IV) initiator. Oxidative modification of the dextran substrate improved the yield of graft copolymer. The dextran-g-poly(acrylamido-co-sodium-2-acrylamido-2-methylpropane sulfonate) samples prepared by this method were characterized as to copolymer composition and molecular weight utilizing elemental analysis, dilute solution viscometry, and aqueous size exclusion chromatography. Relationships of molecular weight and charge density to kinematic viscosity and salt sensitivity are discussed.     

Conformational studies of dammarane‐type triterpenoids using computational and NMR spectroscopic methods

Natural triterpenoids are of great interest to researchers of various fields as they possess diverse physicochemical and biological properties. In medicinal chemistry, detailed information about the chemical structures of bioactive triterpenoids often helps find new lead compounds. Herein, the low‐energy structures of (20S)‐protopanaxadiol and (20S)‐protopanaxatriol, the aglycones of various triterpenoid saponins found in Panax ginseng, and their (20R)‐epimers have been predicted by the geometry optimization of the conformers extracted from molecular dynamics simulations with the self‐consistent‐charge density functional tight‐binding method. By performing quantum mechanical calculations on the low‐energy conformers, we have estimated the NMR chemical shifts of the compounds, which display good agreement with the most recently reported experimental values within an expected range of errors. Our results indicate that theoretical estimation of the NMR parameters of a relatively large molecule with a molecular mass of 500 is feasible. Copyright © 2015 John Wiley & Sons, Ltd.     

Raman and FTIR spectroscopic studies of copolymers of methyl methacrylate with butadiene

The comprehensive characterization by Raman and IR spectroscopy of the products of the free-radically initiated copolymerization of methyl methacrylate with 1,3-butadiene is reported. Raman spectroscopy has been used to determine quantitatively the microstructure of the polymerized 1,3-butadiene units in the copolymers.     

DNA sequencing by capillary electrophoresis using copolymers of acrylamide and N,N-dimethylacrylamide

Copolymers of acrylamide (AM) and N,N-dimethylacrylamide (DMA) with AM to DMA molar ratios of 3:1, 2:1 and 1:1 and molecular weights of about 2.2 MDa were synthesized. The polymers were tested as separation media in DNA sequencing analysis by capillary electrophoresis (CE). The dynamic coating ability of polydimethylacrylamide (PDMA) and the hydrophilicity of polyacrylamide (PAM) have been successfully combined in these random copolymers. A separation efficiency of over 10 million theoretical plates per meter has been reached by using the bare capillaries without the additional polymer coating step. Under optimized separation conditions for longer read length DNA sequencing, the separation ability of the copolymers decreased with decreasing AM to DMA molar ratio from 3:1, 2:1 and 1:1. In comparison with PAM, the copolymer with a 3:1 AM:DMA ratio showed a higher separation efficiency. By using a 2.5% w/v copolymer with 3:1 AM:DMA ratio, one base resolution of 0.55 up to 699 bases and 0.30 up to 963 bases have been achieved in about 80 min at ambient temperatures.     

Analysis of environmental materials using spectroscopic methods

Summary Background levels of environmental materials are the most crucial to be examined for the purpose of environmental monitoring. Lake Mashu water and mussel tissue powders from an unpolluted area are selected as the example for this study. ICP emission spectrometry with a preconcentration procedure by 8-hydroxyquinoline complexation and graphite furnace atomic absorption are among various spectroscopic methods used for the analyses. Colorimetry with an optical fiber type of a total reflection long capillary cell has been found effective for low level fluoride determination in drinking water.

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Analyse von Umweltmaterialien mit spektroskopischen Methoden

Zusammenfassung Die Höhe des Blindwertes von Umweltmaterialien ist für die Überwachung der Umwelt von entscheidender Bedeutung. Wasser vom Mashu-See und Pulver von Muschelgewebe aus einer nicht verunreinigten Gegend wurden als Beispiel für die vorliegenden Untersuchungen ausgewählt. ICP-Emissionsspektrometrie nach Anreicherung durch Komplexierung mit 8-Hydroxychinolin und Graphitofen-Atomabsorption wurden für die Analyse eingesetzt. Colorometrie mit einer totalreflektierenden, einer optischen Faser ähnlichen, langen Capillarzelle erwies sich als geeignet für die Bestimmung niedriger Konzentrationen von Fluorid in Trinkwasser.

     

Critical comparison of evaluation methods of potentiometric titration data using a microcomputer-controlled automatic potentiometric titration system

A microcomputer-controlled automatic potentiometric titrator withP controlled intelligent auto-sampler has been built for serial analysis. Controlling and evaluating programs have also been written. In order to use the most powerful evaluating method, a comparison was made between the methods. The data of the titration curves were obtained by the implicit relation characterizing the curve. The different evaluating methods were tested by using these data. The effects of random errors stemming from measurements were also investigated. The methods used were: two point differentiating formula, differentiation of interpolating and smoothing spline functions, the Gran method, and implicit regression with the Gauss-Newton-Marquardt method. Regression is outstanding among the methods, but it needs much more computing time compared with others. The second-best method is the differentiation with smoothing spline function with end point determination based on finding the sign reversal of the second derivative. This method is much faster than regression.     

Aminoacid N-substituted 1,4,7-triazacyclononane and 1,4,7,10-tetraazacyclododecane Zn2+, Cd2+ and Cu2+ complexes. A preparative, potentiometric titration and NMR spectroscopic study

The pK(a)s and Zn2+, Cd2+ and Cu2+ complexation constants (K) for 1,4,7-tris[(2'S)-acetamido-2'-(methyl-3'-phenylpropionate)]-1,4,7-triazacyclononane, 1, 1,4,7-tris[(2'S)-acetamido-2'-(1'-carboxy-3'-phenylpropane)]-1,4,7-triazacyclononane, H(3)2, 1,4,7-tris[(2'S)-acetamido-2'-(methyl-3'-(1H-3-indolyl)propionate)]-1,4,7-triazacyclononane, 3, and 1,4,7,10-tetrakis[(2'S)-acetamido-2'-(methyl-3'-phenylpropionate)]-1,4,7,10-tetraazacyclododecane, 4, 1,4,7,10-tetrakis[(2'S)-acetamido-2'-(1'-carboxy-3'-phenylpropane)]-1,4,7,10-tetraazacyclododecane, H(4)5, in 20 : 80 v/v water-methanol solution are reported. The pK(a)s within the potentiometric detection range for H(3)1(3+) = 8.69 and 3.59, for H(6)2(3+) = 9.06, 6.13, 4.93 and 4.52, H(3)3(3+) = 8.79 and 3.67, H(4)4(4+) = 8.50, 5.62 and 3.77 and for H(8)5(4+) = 9.89, 7.06, 5.53, 5.46, 4.44 and 4.26 where each tertiary amine nitrogen is protonated. The complexes of 1: [Zn(1)]2+(9.00), [Cd(1)]2+ (6.49), [Cd(H1)]3+ (4.54) and [Cu(1)]2+ (10.01) are characterized by the log(K/dm3 mol(-1)) values shown in parentheses. Analogous complexes are formed by 3 and 4: [Zn(3)]2+ (10.19), [Cd(3)]2+ (8.54), [Cu(3)]2+ (10.77), [Zn(4)]2+ (11.41) [Cd(4)]2+ (9.16), [Cd(H4)]3+ (6.16) and [Cu(4)]2+ (11.71). The tricarboxylic acid H(3)2 generates a greater variety of complexes as exemplified by: [Zn(2)-] (10.68) [Zn(H2)] (6.60) [Zn(H(2)2)+] (5.15), [Cd(2)](-) (4.99), [Cd(H2)] (4.64), [Cd(H2(2))]+ (3.99), [Cd(H(3)2)]2+ (3.55), [Cu(2)](-) (12.55) [Cu(H2)] (7.66), [Cu(H(2)2)]+ (5.54) and [Cu(2)2](4-) (3.23). The complexes of H(4)5 were insufficiently soluble to study in this way. The 1H and 13C NMR spectra of the ligands are consistent with formation of a predominant Zn2+ and Cd2+ Delta or Lambda diastereomer. The preparations of the new pendant arm macrocycles H(3)2, 3, 4 and H(4)5 are reported.     

Water-soluble copolymers of N-vinylamidosuccinic acid with 2-hydroxy-ethylmethacrylate

Data on the peculiarities of obtainment and properties of water-soluble N-vinylamidosuccinic acid copolymers with 2-hydroxy-ethylmethacrylate are generalized. The results of viscosimetric and potentiometric investigations of synthesized polymer analogs—N-vinylamidosuccinic acid copolymers with 2-hydroxy-ethylmethacrylate—are presented.     

Rapid potentiometric methods for uranium and for analysis of mixtures using potassium bromate

This investigation is an application of the method involving determination of uranium(VI) based on reduction to uranium(IV) with zinc metal in acidic medium, and then oxidation by adding a known excess of bromate. Boiling to expel the liberated bromine then adding sulfite and 1 ml 10% sulfuric acid, expel excess sulfite, cooling and titrating the liberated bromide with silver(I), using silver amalgam as indicator electrode in conjunction with calomel electrode. Binary and ternary mixtures are successfully analyzed. The present methods have advantages over the classical ones of being simple, rapid, and reliable.     

The synthesis of crosslinked copolymers of maleilated chitosan and acrylamide

By acylating chitosan with maleic anhydride in formamide medium trisubstituted products (on one amine and two hydroxyl groups of the saccharide unit) have been obtained, as has been confirmed by IR spectroscopy, titration carboxylic groups, and determination of the content of olefin bonds. By copolymerizing trisubstituted maleilated chitosan and acrylamide in water solution crosslinked polymers have been obtained. Their swelling in water decreases with an increase in the share of maleilated chitosan in the initial mixture of reagents and with a decrease in dilution of the initial mixture of reaction components. Consumption of maleilated chitosan double bonds in this case varies from 40 to 70%.