Formation of hydroxyl endgroups in polymers and their detection by dye tests

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Abstract
The following possibilities of introducing hydroxyl endgroups in polymers have been experimentally realized: (1) redox initiation by ferrous sulfate + H2O2 (Fenton's reagent), N2H4, H2O + H2O2, FeCl3 + H2O2; photoinitiation by Fe(OH)++ + light, H2O2 + ultraviolet light or sunlight, and initiation by unstable Ag+++ complex in dark; (2) copolymerization with a trace of allyl alcohol or with traces of vinyl acetate and allyl acetate and subsequent hydrolysis; (3) chain transfer with butyl alcohols. The method of detection consists in first converting hydroxyl endgroups to carboxyl endgroups by refluxing with phthalic anhydride or 3‐nitrophthalic anhydride in benzene and pyridine medium or with maleic anhydride in benzene medium and testing the resulting polymer for carboxyl endgroup by the dye‐interaction test with rhodamine 6GX dye extract. The hydroxyl endgroup was also quickly converted to a strong acid endgroup like OSO3H by reacting the polymer with chlorosulfonic acid in chloroform medium under controlled conditions and tested by the dye‐interaction test or a dye‐partition test with methylene blue. This test is not entirely satisfactory, as the reagent attacks the thermal polymers slightly.