Amides from N-phenylpiperazine as low-toxicity activators in radical polymerizations

Abstract N ′-Acryloyl- (AcrNPP), N ′-methacryloyl- (MetNPP) and N ′-acetyl- N -phenylpiperazine (AcNPP) were synthesized and tested as activators in the benzoyl peroxide radical ‘cold curing’ of methyl methacrylate at 40°C. The three amides showed quite similar efficiencies as redox reducing agents, but different migrabilities from the final polymer. In amide release tests in methanol, the highest value was obtained with AcNPP; a notably lower release was observed with MetNPP and AcrNPP, the lowest being with the latter. This behaviour of the unsaturated amides is discussed in relation to their measured ability to copolymerize, as well as in relation to other factors affecting migrability.