Kinetics of alkaline hydrolysis of polyacrylamide in solution by viscosimetric technique

Gunari, A. A.; Gundiah, S.

doi:10.1002/macp.1981.021820101

Cited by 20 publications

(7 citation statements)

References 5 publications

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“…Moens et al 1 investigated the process of alkaline hydrolysis as change in electric conductivity of the system by measuring the increase of negative charge due to conversion of the carbamoyl group to the ionic carboxyl group. Gunari et al 2 analyzed its kinetics by measuring the viscosity of the aqueous (aq) solution of hydrolyzed PAA, because the viscosity varied in proportion to the degree of hydrolysis of PAA. Moens et al 1 and Gunari et al 2 speculated that the carbamoyl group was not randomly hydrolyzed and the carbamoyl group in the acrylamide (A) monomer unit adjacent to the acrylic acid (B) monomer unit produced by alkaline hydrolysis of PAA was strongly resistant to further alkaline hydrolysis, finally leading to the formation of * To whom all correspondence should be addressed.…”

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confidence: 99%

Study on Alkaline Hydrolysis of Polyacrylamide by 13C NMR

Yasuda¹,

Okajima²,

Kamide³

1988

Polym J

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ABSTRACT:Alkaline hydrolysis of a polyacrylamide sample was performed in aqueous sodium hydroxide (Na0H) solutions at various Na0H concentrations to investigate the effects of hydrolysis conditions on the sequence distribution of the hydrolyzed products. For this purpose, 13 C NMR spectra for the aqueous solutions of the products were measured, in order to determine the sequence distribution based on carboxyl (on acrylic acid residue) and carbamoyl (on acrylamide residue) carbon peak assignments. It was first found that the specific concentration of aqueous sodium hydroxide solution gives a product with a sequence distribution greatly differing from the conventional product whose sequence distribution is almost completely alternative of acrylic acid and acrylamide residues. Under the other hydrolysis conditions employed here, the products with almost alternative sequence distribution were found to be commonly produced. Possible hydrolysis mechanisms are discussed based on the structures of aq Na0H solutions.KEY WORDS 13 C NMR / Polyacrylamide / Alkaline Hydrolysis/ Sequence Distribution / Many studies have been carried out on the alkaline hydrolysis of the carbamoyl group in polyacrylamide (PAA) to carboxyl group. Moens et al. 1 investigated the process of alkaline hydrolysis as change in electric conductivity of the system by measuring the increase of negative charge due to conversion of the carbamoyl group to the ionic carboxyl group. Gunari et al. 2 analyzed its kinetics by measuring the viscosity of the aqueous (aq) solution of hydrolyzed PAA, because the viscosity varied in proportion to the degree of hydrolysis of PAA. Moens et al. 1 and Gunari et al. 2 speculated that the carbamoyl group was not randomly hydrolyzed and the carbamoyl group in the acrylamide (A) monomer unit adjacent to the acrylic acid (B) monomer unit produced by alkaline hydrolysis of PAA was strongly resistant to further alkaline hydrolysis, finally leading to the formation of * To whom all correspondence should be addressed.ABABAB type polymer. This kind of autoretarded reaction has already been proposed by Fuoss et al.3 in the case of quaternization of poly(4-vinylpyridine) by alkyl halide. Higuchi et al. 4 supported the above speculation on the hydrolysis model of PAA using experimentally determined rate constants of hydrolysis of A unit in AAA, ABA, and BAB sequences. Halverson et al. 5 directly measured the 13 C NMR spectra of the alkaline solution of PAA, in which PAA was hydrolyzed to the desired degree. Here, note that they used a hydrolysis media consisting of water and sodium chloride (0. 75 mol 1 -i) or isopropanol (2 wt%) and stoichiometrical amount of sodium hydroxide (NaOH) (0.23--0. 7 mol) for the desired hydrolysis degree of PAA using the polymer solution with its concentration of 5 and 9 wt%. They analyzed carbonyl carbon peaks for A and B monomer units and suggested that 1101

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confidence: 99%

Study on Alkaline Hydrolysis of Polyacrylamide by 13C NMR

Yasuda¹,

Okajima²,

Kamide³

1988

Polym J

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“…Poly(acrylamide‐ co ‐acrylic acid) copolymer (PAM‐τ, where τ denotes degree of hydrolysis) had molecular weight 200 kDa and was purchased from Aldrich (τ equal to 20%). Potentiometric titration28 of this component showed the degree of hydrolysis to be equal to the nominal value (20%). Because the pH was adjusted with addition of NaOH to ensure full ionization of the acrylate units in solution, there is a possibility of hydrolysis of acrylamide groups on the polymer backbone during equilibration of samples.…”

Section: Methodsmentioning

confidence: 88%

Partitioning of anionic/nonionic polysaccharides in a segregative system of anionic polyelectrolyte mixtures in aqueous solution: Effects of polymer charge density and ionic strength of solution

Hellebust

Blokhus

Nilsson³

2006

J of Applied Polymer Sci

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The partitioning of three polysaccharides, Dextran sulfate (DxS), λ‐Carrageenan (CAR), and Dextran (Dx), and its dependence on polymer charge density and ionic strength have been investigated in the segregative mixture of poly(sodium styrene sulfonate) (NaPSS) and sodium polyacrylate‐acrylamide copolymers, NaP(AA/AM), of variable charge density, in aqueous solutions. It is shown that the solubility of all the three may be zero or finite in one or both phases, but the preferred phase is determined by the charge density on the copolymer. When charge densities are equal on the phase forming polymers, the saccharides CAR and Dx favor the phase rich in PSS, but they have greater affinity for the polymer of lower charge density when the charge densities on phase polymers are unequal. The partitioning behavior of DxS is the opposite of the other two polysachharides with respect to which phase it has the greatest affinity for. The values of the partitioning coefficients show that the system may be potentially useful for the purification of polysaccharides and other macromolecules, if appropriate conditions are selected. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1728–1734, 2006

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“…The initial rate burst for the latter reaction is attributed to the = 5% head-to-head sequences in the parent PAM polymer [269,270]. It is reasonable, based on electrostatic effects, that hydroxide ions would be more effective in promoting hydrolysis for the AAA sequence than for the AAB-or BAB-sequences.…”

Section: Polyamidesmentioning

confidence: 97%

“…These polymers are noted for their water solubility and hydrolytic stability compared to esters. However, in strong acid or base and at elevated temperatures they do hydrolyze and this reaction has been studied by several groups [267][268][269][270][271]. Under basic conditions, base/amide = 10/1, both polymers were subject to autodeceleration, i.e.…”

Section: Polyamidesmentioning

confidence: 99%