Date of Award
Doctor of Philosophy (PhD)
Chloromethyl methyl ether, 6, generated in situ by reaction of dimethoxymethane with acetyl chloride, was employed to chloromethylate condensation polymers containing oxy-1,4-phenylene repeat units, i.e. poly(oxy-2,6-dimethyl-1,4-phenylene), 3, polyarylether sulfone, 4, and acetylated phenoxy resin, 10. To minimize concomitant crosslinking, the optium reaction ratios are 20:1:0.1 for reagent 6 to polymer to SnCl(,4) catalyst. One chloromethyl group per activated aromatic ring could be introduced: the corresponding concentration of active sites were 5.8, 3.5, and 4.6 meq/g for derivatives of 3, 4, and 10, respectively. All of the derivatives were characterized by NMR, DTA, and TGA techniques. A model segment of polyarylether sulfone was synthesized by condensing 4-chlorophenyl phenyl sulfone with the disodium salt of bisphenol-A. Chloromethylation of the model segment yielded a bischloromethyl derivatives, 14. Quaternization of 14 with tertiary amines in DMSO proceeded to completion: no deviation from second order kinetics was observed. The initial quaternization rate of chloromethylated polyether sulfone, 9, with either triethylamine or quinuclidine was nearly identical to that of 14 under comparable conditions, but deceleration of the reaction on the polymer was apparent at approximately 50% conversion. The rate retardation could not be attributed to steric effect, the extent of chloromethylation of 4, or salt effect. In the quaternization of chloromethylated acetylated phenoxy resin, 11, with triethylamine in DMSO, a rate retardation was observed at 60% conversion. Normal second order kinetics was observed for quaternization of poly(vinylbenzyl chloride). These results demonstrate that the flexibility of the polymer backbone plays an important role in polymer reactivity, particularly when there is a significant change in the polarity of the modified polymer. Rigid polymer chains can not undergo the conformational changes necessary to form charged domains. Quaternization of the moderately flexible 11 with either 2-hydroxyethyldimethylamine, 18, or bis(2-hydroxyethyl)methylamine,19, in DMSO proceeded with autoacceleration. Selective solvation of the developing charges by the hydrophilic hydroxylated substituents may contribute to the rate enhancement. However, quaternization with tri(2-hydroxyethyl)amine exhibited rate retardation when approximately 20% of the functional groups had reacted. Reactions of 18 and 19 with 9 also developed a negative deviation from second order kinetics as the reaction proceeded.
Wu, Shih-jen, "Chemical Modifications of Condensation Polymers, Chloromethylation and Quaternization." (1983). LSU Historical Dissertations and Theses. 3948.