Approach To Predict Copolymer Compositions in Case of Variable Monomer Reactivity

Abstract

An analytical approach to predict copolymer compositions is presented for the particular case that the reactivity of one monomer (B) alters under the influence of one measurable medium parameter. Terpolymerization mathematical treatment was applied to binary systems (A/B), which turn into ternary systems (M 1, M2, M3) in a defined range between two extremes of the medium parameter. The approach needs as input data a relationship describing the coexistence of two derivatives (M2, M3) of B as a function of the influencing parameter, knowledge of homopolymerization kinetic data of B, and reactivity ratios, rA and rB, only at the extremes of the variable medium parameter. As a case study, the copolymerization of acrylamide/acrylic acid mixtures in aqueous medium was selected with the pH as variable parameter. Good agreement of predicted and experimental data was proved. The approach provides a useful tool to significantly decrease the number of polymerization experiments needed to identify the effect of medium parameters on the polymerization kinetics. The principle of the approach is proposed to treat any set of two monomers if one alters the characteristics under the influence of any measurable medium parameter.

Preparation and characterization of narrow compositional distribution polyampholytes as potential biomaterials: Copolymers of N‐(3‐aminopropyl)methacrylamide hydrochloride (APM) and methacrylic acid (MAA)

“…An early study of a polyampholyte composed of MAA and N , N ‐dimethylaminoethyl methacrylate (DMAEMA) found that the reactivity of MAA was greatly affected by its degree of ionization unlike DMAEMA, probably related to the proximity of the ionizable group to the double bond in MAA. The copolymerization of acrylamide with MAA or acrylic acid (AA) has been found to have reactivity ratios that are very sensitive to pH such that the acid monomer is preferentially incorporated at low pH and acrylamide at high pH . In the case of acrylamide/AA, the crossover point, where the reactivity ratios are equal, occurs at a pH of about 4.2, which is close to the p K a of AA …”

“…The copolymerization of acrylamide with MAA or acrylic acid (AA) has been found to have reactivity ratios that are very sensitive to pH such that the acid monomer is preferentially incorporated at low pH and acrylamide at high pH. [25][26][27][28] In the case of acrylamide/AA, the crossover point, where the reactivity ratios are equal, occurs at a pH of about 4.2, which is close to the pK a of AA. 25 Copolymers with various APM to MAA ratios were targeted in this work such that polyampholytes with net charges that were anionic, near neutral and cationic at physiological pH could be obtained.…”

Optimal estimation of reactivity ratios for acrylamide/acrylic acid copolymerization

“…There is much debate about the actual values of the reactivity ratios of this copolymerization because of the complexities arising from the actual forms of the monomer in solution mentioned earlier . Reactivity ratios for AAm/AAc copolymerization have been “determined” by several groups and the results are summarized in Table .…”

“…There is much debate about the actual values of the reactivity ratios of this copolymerization because of the complexities arising from the actual forms of the monomer in solution mentioned earlier. 11 Reactivity ratios for AAm/AAc copolymerization have been "determined" by several groups and the results are summarized in Table 1. Since SA monomer may also exist in the aqueous solution depending on the experimental conditions, reactivity ratios for AAm/SA are also presented in the Table. Overall, it can be seen from Table 1 that there is a wide range of values for the reactivity ratios, despite the fact that the qualitative trend is similar among all studies: an increasing trend for r AAm with increasing pH, whereas r AAc decreases.…”

Online Monitoring of 4‐Vinylbenzene sulfonic acid Sodium Salt – Acrylamide Copolymerization in Water

“…However the reactivity ratios of charged monomers depend strongly on the pH and less strongly on the total ionic strength of the solution. [20,39,40] In general, the reactivity of a monomer decreases as it becomes ionized. This behavior can be understood as a result of the electrostatic repulsion between the ionic monomer and the charged polymer coil.…”