Title

(1) AUTOCATALYZED HYDROLYSIS OF ACRYLIC POLYMER COLLOIDS: A KINETIC AND CARBON-13 NMR STUDY. (2) SYNTHESIS OF MONODISPERSE, SPIN-LABELED, AMPHIPHILIC POLYMERS OF STEARIC ACID AND POLY(ETHYLENE GLYCOL) (POLYETHYLENE)

Date of Completion

January 1983

Keywords

Chemistry, Polymer

Degree

Ph.D.

Abstract

Methyl acrylate polymer colloids can be hydrolyzed self-catalytically by bound strong acid groups chemically bound to the particle surface which are derived from the polymerization initiator. The kinetics of hydrolysis, after an initial surge are shown to be apparently pseudo-zero order for any given latex, and first order with respect to surface strong acid concentration. A reaction zone model is proposed to explain the kinetics. It also leads to the prediction that the polymer particles will possess a core-shell morphology after some hydrolysis has occurred. This study used ('13)C NMR to investigate the particle morphology in the wet latex, a new application for this method. The temperature-dependence of the ('13)C NMR integrated intensities at various levels of hydrolysis provides strong evidence that the particles do possess core-shell morphology, and that the shell is composed of PAA/PMA copolymer. This shell is swollen and plasticized by water, resulting in greatly enhanced segmental mobility of the polymer chains as evidenced by marked narrowing of the NMR lines. Consistent with the kinetics and NMR results, a quantitative expression based upon a model involving two concentric surface reaction zones was derived.^ In a separate study, methods were developed for the synthesis of monodisperse, spin-labeled, colloidal stabilizers made from 12-keto-stearic acid and poly(ethylene glycol), PEG. The diester was made from a PEG with molecular weight of 4000 and 12-keto-stearyl chloride. In separate experiments it was shown that 12-keto-methyl stearate could react with 2-amino-2-methyl-1-propanol to form the corresponding dimethyl oxazolidine. This was subsequently oxidized to form the nitroxyl free radical spin-label, which exhibited the expected triplet-peak ESR spectrum. ^