Kazuo Shiraki

Preparation and Thermal Decomposition of Cyclic Azoamidinium Salts as Water-Soluble Radical Initiators for Polymerization over A Wide Temperature Range

Abstract A series of cyclic azoamidinium chlorides as water-soluble initiators were prepared by reactions of the iminoether derived from 2,2′-azobisisobutyronitrile with substituted alkylene diamines. The first-order rate constants for the decomposition of the azoamidinium salts varied from 0.59 × 10−5 to 14.1 × 10−5 s−1 with the ring size and the alkyl substitution of the ring. Decomposition of 2,2′-azobis[2-(imidazoline-2-yl)propane] dihydrochloride was found to be accelerated by alkyl substitution on the imidazolinium ring. However, the azoamidinium compounds having larger rings, 2,2′-azobis[2-(3,4,5-trihydropyrimi-dine-2-yl)propane] dihydrochloride and 2,2′-azobis[2-(4,5,6,7-tetra-hydro-1H-1,3-diazepine-2-yl)propane] dihydrochloride, decomposed at a slower rate than the unsubstituted azobis[2-(imidazoline-2-yl)-propane] dihydrochloride. These new initiators were found to be capable of initiating radical polymerizations of acrylamide and vinyl acetate.

Graft polymerization of allyl benzoate using poly(allyl benzoate-co-2,2'-azobis[N-(2-propenyl)-2-methylpropionamide]) as polymeric azo-initiator

2,2′-Azobis[N-(2-propenyl)-2-methylpropionamide] (APMPA), a diallyl azo-compound useful as an initiator at elevated temperatures, was copolymerized with allyl benzoate (ABz) at 60°C, providing poly(ABz-co-APMPA) which acts as a polymeric azo-initiator. The effectiveness of poly(ABz-co-APMPA) to give a novel graft copolymer was checked by polymerizing ABz at 120°C and, furthermore, by the polymerization of styrene accompanied by crosslinking through termination by bimolecular combination.