Free Radical Graft Copolymerization of Methyl Methacrylate onto Polyolefin Backbone: Kinetics Modeling through Model Compounds Approach

Abstract

The grafting of poly(methyl methacrylate) (PMMA) from poly[ethylene‐co‐(1‐octene)] in the molten state by in situ radical polymerization of methyl methacrylate (MMA) was investigated through a kinetic modeling using a model compound approach. We resorted to pentadecane (C15H32) and 2,6,10,15,19,23‐hexamethyltetracosane (Squalane, C30H62) as models for both the copolymer ethylene and octene moieties. The attention was focused on the simulation of MMA conversion and PMMA average polymerization degree according to temperature, reaction time, and initiator ratio required for the polymerization of MMA in the presence of alkoxyl radicals and alkanes.magnified image

Synthesis of polyethylene‐grafted multiwalled carbon nanotubes via a peroxide‐initiating radical coupling reaction and by using well‐defined TEMPO and thiol end‐functionalized polyethylenes

“…The main step is the formation of DCP‐derived alkoxy radicals that abstract hydrogen from the PE backbone. However, the alkoxy radicals can undergo additional reactions including β‐scission leading to the formation of methyl radicals 26, 27. These latter preferentially induce coupling reaction or attack onto the sp 2 carbon of the MWCNTs whereas cumyloxyl radicals are more prone to hydrogen abstraction from PE 28.…”

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

“…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.…”

Synthesis of Poly(methyl methacrylate)‐Grafted Poly(ethylene‐co‐1‐octene) Copolymers by a “Grafting from” Melt Process

“…Main reactive pathways of free radical grafting from poly(ethylene ‐co‐ 1‐octene) backbone (PH) with DCP as hydrogen abstractor is published elsewhere for alkanes 32–34. According to the latter previous work, we have shown that, whatever the initiator is, a temperature decrease from 170 to 150 °C improved grafting.…”

“…Therefore, the depropagation reaction is not favored by increasing monomer concentration leading to an increase of both monomer conversion and PMMA molar mass. Our previous numerical simulation of the grafting polymerization of MMA from alkanes in the presence of a peroxide initiator at temperatures varying from 100 to 200 °C enables to fit these experimental results 32. Contrary to monomer conversion and PMMA molar mass, the grafting efficiency logically decreases from 42 to 33% by increasing monomer concentration from 30 to 50 wt% (Table 4).…”

“…Moreover, performing this chemical modification by reactive processing brings many constraints inherent to the process (e.g., short reaction time, viscous dissipation, and high temperature). As a result, in order to separate these physical influences from the chemical modification, some authors developed a model compound approach based on the selection of a set of low molar mass alkanes 11, 29–34. In the temperature range 150–170 °C, we showed32–34 that the graft methyl methacrylate propagation reaction onto pentadecane had to face up to a depropagation phenomenon, which lowered the poly(methyl methacrylate) (PMMA) polymerization degree and monomer conversion to 44 and 43%, respectively.…”