Kinetic study on reactions between polymer chain-ends—II. Reactions between chlorosulphonyl-ended and primary amino-ended polyoxyethylenes followed by fluorometry

Abstract

Rates of the reaction of 1,5-naphthalenedisulphonyl dichloride, a bifunctional fluorescent reagent, with primary amino-ended polyoxyethylene were measured by fluorometry in dilute solution. The second-order rate constants obtained are equivalent to those for the reaction between polyoxyethylenes with chlorosulphonyl and primary amino groups as the reactive chain-ends respectively (polymer-polymer reaction). Rates of the reaction of 5-dimethylamino-1-naphthalenesulphonyl chloride, a monofunctional fluorescent reagent, with primary amino-ended polyoxyethylene were also measured as model (small molecule-polymer) reactions. In both cases the rates of reaction in cloroform (good solvent) are substantially independent of the degree of polymerization over the range of about 20 to 20,000. These and previous results show clearly that, if there is a “kinetic excluded volume effect”, it is very small and Flory's principle of equal reactivity of a functional group holds. Recent theories of the kinetic excluded volume effect are discussed briefly.