Alkaline and acid hydrolysis of polyvinylamides

Abstract

When macromolecules take part in organic reactions, one has to consider the influence of polymeric structure not only on the course of the reaction but also on the final structure of the end products. Indeed, as the reaction proceeds, interactions may occur between different structural units ; moreover, if the polymeric chain becomes charged in the course of the reaction, an electrostatic repulsion potential between the functional groups and between the functional groups and the reagent will affect the over-all shape of the molecule and the effective concentration of the reagent in the neighborhood of the macromolecule. Consequently these effects will have a direct influence on the kinetics of the reaction.In order to demonstrate these effects, it seems interesting to consider a well-known reaction of organic chemistry-the acid and alkaline hydrolysis of amides, and its application to polyacrylamide, polymethacrylamide, and some of their derivatives. In an alkaline medium the macromolecule becomes negatively charged and the electrostatic potential increases with degree of conversion; in an acidic medium interactions between acid and amide functional groups make possible the formation of intramolecular imide groups.In this paper we will consider successively: ( I ) the alkaline hydrolysis of polyacrylamide and of polymethacrylamide ; (2) the acid hydrolysis of both polyvinylamides. ALKALINE HYDROLYSIS OF POLYVINYLAMIDESThe alkaline hydrolysis of amides is a second-order reaction proportional to both the amide and the hydroxyl ion concentration^.'-^ The rates of the reactions in aqueous solution have been followed by conductometric titration, using stoichiometric concentrations of amide and sodium hydroxide (N/20). The corresponding second-order rate constants K20H-were obtained by plotting the reciprocal value of the amide concentration against time and evaluating the slopes of the diagrams.In order to determine the rate of reaction at a high degree of conversion or in the cases in which the reactions proceed very slowly, some experiments were also carried out with a tenfold excess of sodium hydroxide. In these cases apparent first-order rate constants klOH-were obtained from plots of the logarithm of the residual amide concentration against time. 931

Synthetic Hydrogels for Biomedical Applications

“…A number of studies have been carried out on the hydrolysis of acrylamide and methacrylamide polymers (73)(74)(75).…”

Novel pH‐ and Temperature‐Responsive Methacrylamide Microgels

“…[25,30,31] In this case the cyclization could take place between MeAm units or between MeAm and NPA units (see Figure 6). …”

Effect of the Properties of Polyelectrolytes on Their Catalytic Behavior. I

“…This is due to the fact that, in parallel to the effect of heating hydrolysis, an imide-formation reaction occurs [9], during which an amide group reacts with a vicinal carboxyl group within the chain or with another carboxyl group in a favorable position. The reaction proved to be proton-consuming.…”