Hydrolysis of poly(vinyl acetate)s of various tacticities

Fujii, Kiyoshi; Ukida, Junji; Matsumoto, Masakazu

doi:10.1002/pol.1963.110011210

Cited by 34 publications

(8 citation statements)

References 8 publications

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“…It has been reported that the rate of hydrolysis is slightly higher for the low molecular weight than for the highmolecular weight PVAc. [15] However, more work is needed to explain the effect observed in this research.…”

Section: Critical Micelle Concentrationmentioning

confidence: 87%

Surfactant Concentration Effects on the Aqueous Phase Polymerization of Vinyl Acetate

Martínez‐Gutiérrez

Ovando‐Medina

Peralta

2009

Macromolecular Symposia

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Summary: Vinyl acetate (VAc) in concentrations below the water saturation value was polymerized by batch processes at 60 8C using low surfactant concentrations of sodium dodecyl sulfate (SDS) and potassium persulfate (KPS) as initiator. The effects of surfactant concentration on the reaction kinetics, particle formation and molecular weight were studied. It was found that the average particle diameters decrease between 277 and 18.7 nm as the surfactant concentration is increased from 0 to 11 mmol/L, whereas the weight average molecular weight (Mw) decreases also, with values between 8.7 Â 10 5 Mw 1 Â 10 5 Da. It was observed that particle size distributions are strongly affected by the addition of small amounts of surfactant. For the low monomer concentrations used in the polymerizations (0.0137 g/cm 3 of water), particles were very stable and no coagulation was observed. High reaction rates were found in all polymerizations. When no SDS was added to the system, lower polymerization rates were obtained at the onset of the reaction due to the low rate of particle formation. The behavior of polymerization rate was inversely proportional to the surfactant concentration, which was ascribed to the increase in the average number of radicals per particle.

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Section: Critical Micelle Concentrationmentioning

confidence: 87%

Surfactant Concentration Effects on the Aqueous Phase Polymerization of Vinyl Acetate

Martínez‐Gutiérrez

Ovando‐Medina

Peralta

2009

Macromolecular Symposia

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“…Our case is rather more complicated than that of end-groups. There are many known factors affecting this type of reaction : electrostatic,l0-'2 specific, [13][14][15] or catalytic effect of neighboring groups, [16][17][18][19] and also the effect of diffusion . 20 The present work was undertaken to determine whether the degree of coiling might be another factor influencing the kinetics of side-group reactions in macromolecules.…”

Section: Introductionmentioning

confidence: 99%

A possibility of influence of the degree of coiling of macromolecules in solution on the kinetics of side‐groups reactions

Turska

Jantas

1974

J. polym. sci., C Polym. symp.

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SYNOPSISPapers published earlier have shown that the accessibility of the end-groups, in conjunction with the degree of coiling of the macromolecules, undoubtedly affects the kinetics of reactions in solutions.Our work was carried out in order to investigate the possibility of an analogous phenomenon in the case of reactions involving side-groups. We considered the factors which have been supposed, until now, to influence these reactions. We suggested that together with other factors the degree of coiling could influence the course of the reaction. To check the validity of this suggestion, a number of kinetic measurements were made of the hydrolysis of poly (vinyl acetate) and specially chosen model compounds in selected mixed solvents. Low-molecular weight substances, as well as partially hydrolized poly (vinyl acetate), were investigated as model compounds. The experimental data obtained were considered in various apsects, taking into account both our suggestions and those by other authors. It was found that not all the observed phenomena could be explained without using our theory. 359

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“…( la) Typical examples of such effects are the enhancement of the solvolysis of phenyl ester groups by neighboring ionized carboxyls, (2,3) of amide or anilide groups by un-ionized carboxyls, (4,5) and of acetate groups by neighboring hydroxyls. (6)(7)(8) A different problem arises when the interacting groups are not located on neighboring residues of the polymer chain. In this case, the rate of the process will reflect the *Dedicated to Professor Herman F. Mark in honor of his 75th birthday.…”

Section: Introductionmentioning

confidence: 99%

Reaction kinetics in dilute solutions of chain molecules carrying randomly spaced reactive and catalytic chain substituents. I. Estimation of ring closure probabilities from kinetic data and computer simulation

Goodman¹,

Morawetz²

1970

J. polym. sci., C Polym. symp.

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SYNOPSISAcrylamide was copolymerized with small proportions of monomers containing a p-nitrophenyl ester group and a small amount of a monomer containing a pyridine residue. The hydrolysis of the ester groups was studied under conditions where the rate of the process was controlled by interaction with pyridine residues attached to the same chain.Variables studied included the mode of attachment of the ester groups t o the chain backbone, the concentration of the catalytic pyridine residues in the chain and the fraction of the pyridine present in the unprotonated, catalytically active form. Kinetic data obtained at different pH values gave the same results if the extent of reaction was expressed as a function of the product of the experimental time and the fraction of pyridine residues in the basic form, This proves that the intramolecular process is not controlled by the rate at which cyclic conformations are formed but by their probability. The reaction deviated from first-order kinetics because the reactive groups had varying spacings from the catalytic groups. Experimental data were in good agreement with the kinetics derived by computer simulation if the probability of group interaction was made inversely proportional to the square of their separation along the chain molecule. Initial apparent first-order rate constants were about 40% of the value predicted on the basis of a simple theory based on the average extension of the polymer coils.

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Hydrolysis of poly(vinyl acetate)s of various tacticities

Cited by 34 publications

References 8 publications

Surfactant Concentration Effects on the Aqueous Phase Polymerization of Vinyl Acetate

Surfactant Concentration Effects on the Aqueous Phase Polymerization of Vinyl Acetate

A possibility of influence of the degree of coiling of macromolecules in solution on the kinetics of side‐groups reactions

Reaction kinetics in dilute solutions of chain molecules carrying randomly spaced reactive and catalytic chain substituents. I. Estimation of ring closure probabilities from kinetic data and computer simulation

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