An Aliphatic Bifunctional Free Radical Initiator. Synthesis of a Block Copolymer from an Azoperester by Sequential Thermal and Photochemical Initiation

Abstract

The azoalkaneperester tert-butyl 7-methyl-7-(tert-butylazo)peroxyoctanoate (7) has been found to be a viable bifunctional free radical initiator. Unlike the radicals from previously studied compounds 4−6, those from 7 neither fragment nor cyclize, presumably on account of the medium ring that would be required. Thermolysis of 7 with styrene affords macroinitiator 21 while photolysis affords 22. Photolysis of 21 with MMA yields block copolymer 23 while thermolysis of 22 with MMA affords block copolymer 24. One advantage of 7 is that the photolysis−thermolysis sequence can be reversed, as can the order of addition of monomers.

Synthesis and Characterization of a Series of Homooligopeptide Peroxyesters

“…Peroxyesters are extensively exploited as initiators for the radical polymerization of vinyl compounds and represent useful sources for kinetics studies in radical chemistry, as they exhibit fast homolytic decomposition in the presence of nucleophiles and by thermolysis or photolysis . Peroxyesters are also used as oxidants in the Kharasch−Sosnovsky, copper-catalyzed, allylic oxidation reaction …”

Reactions of N-alkylhydrazones of aliphatic ketones

“…В літературі описано алкілування гідразону 7 трет-бутил-6-йодогексаноатом, яке із виходом 52% приводить до азопохідної 25, яка знайшла використання для бірадикального ініціатора для полімеризації різноманітних похідних стиролу син-тезу [25] (схема 11).…”

Radical initiators and their influence on the viscosity and molecular weight of acrylic polymers applied in pressure-sensitive adhesives

“…Because of the similar decomposition temperatures of azo and peroxy groups, azoperoxy compounds are not suitable for obtaining well-defined block copolymers when both stages of the polymerization process are initiated thermally. If one of the stages is initiated photochemically, and the other one thermally, nevertheless, the results are satisfactory [12].…”