N-Acetoxy-phthalimide (NAPI) as a new H-abstracting agent at high temperature: application to the melt functionalization of polyethylene

Abstract

International audienceA new H-abstracting agent, N-acetoxy-phthalimide (NAPI), was designed that cleaves mainly homolytically into acyloxyl and aminyl radicals at 190 degrees C. Melt PE grafting experiments confirmed the H-abstraction efficiency of NAPI. It was also shown that the grafting of maleic anhydride increased and at the same time undesired crosslinking lowered compared to peroxides

Effect of nitroxyl-based radicals on the melt radical grafting of maleic anhydride onto polyethylene in presence of a peroxide

“…First of all, the effect of the thermolysis of L101 on the polyethylene backbone was studied through linear viscoelastic measurements which allow to monitor even slightly modification of the PE macromolecular architecture after a cross-linking reaction [23,41]. Since peroxide thermolysis is a relatively slow first-order decomposition that controls the rate of subsequent radical reactions [42], cross-linking rates are, therefore, fastest in the early stages.…”

“…the reactions non-selective. As initiator, dialkyl peroxides are most commonly used and the decomposition mechanism involves initial O-O bond homolysis to generate the corresponding alkoxy radicals that can add to the grafting monomer, which would lead to homopolymers as undesired by-products [20][21][22][23][24]. Alkyl radicals formed by decomposition of the primary radicals are known to preferably add to the monomer.…”

Functionalization of poly(lactide) with N‐phenyl maleimide using N‐acetoxy‐phthalimide during reactive extrusion

“…However, a peroxide initiator was still needed to form the PLA macroradicals. N ‐Acetoxy‐phthalimide (NAPI) was proposed as an alternative to conventional peroxides in polyolefin functionalization . Density functional theory calculations showed that thermal degradation of NAPI preferentially led to the formation of α,α′‐dioneaminyl‐based radicals, with very efficient H‐abstraction ability.…”

“…Density functional theory calculations showed that thermal degradation of NAPI preferentially led to the formation of α,α′‐dioneaminyl‐based radicals, with very efficient H‐abstraction ability. In a lower extent, phthalimide‐ N ‐oxyl (PINO) radicals (nitroxide) were also formed and scavenged the macroradicals . In a recent paper, we showed that thermal degradation of NAPI during PLA reactive extrusion could be used to form PLA macroradicals, and to graft some nitroxides (up to 0.24 mol %) onto the PLA backbone, without the use of peroxide.…”

Synthesis and Characterization of Comb‐Like Copolymers Based on Poly(ε‐caprolactone) and Poly(α‐olefin)

“…Polyolefins with their annual industrial production exceeding 100 million tons are the most widely used commercial polymers . However, ecological demands have attracted researchers' attention to biodegradable and biobased polymers.…”