Interaction between Radicals Derived from Two Di-t-Alkyl Peroxides with Some Monomers and Polymers

Abstract

The thermolysis of di-tert-butyl and di-t-amyl peroxides in n-decane and with poly(methyl methacrylate) and poly(ethylene glycol) in chlorobenzene has been studied in the presence of tri-tert-butylnitrosobenzene as a spin trap. The major reaction pathways of the resulting t-alkoxyl radicals were β-scission and hydrogen atom abstraction. Thermolysis of the same peroxides in the presence of methyl methacrylate and methyl acrylate led to the trapping of growing polymer chains alongside unreacted alkyl radicals (again formed via β-scission of the first generation t-alkoxyl radicals). In some of the spectra, hyperfine coupling to γ-protons was observed. The hydrogen abstracting ability of radicals present during thermolysis of both peroxides has been compared in the presence of MA.

Conformal single-layer encapsulation of PEDOT at low substrate temperature

“…Besides the effect of P M / P sat , temperatures of the filament (T f ) can also affect the deposition rate in the synthesis of PDVB-MA. Previous publication indicates the degree of decomposition of TBPO increases as T f increases when T f < 270 °C, and higher T f results methyl radicals [40], which is more reactive than the tert-butoxy radicals and therefore accelerate the freeradical polymerization. [41] 3.2 Conformality, uniformity, and surface roughness…”

Dual monomer grafting of styrene and maleic anhydride onto model hydrocarbon substrates

“…Abstraction is not expected to occur significantly at methyl carbons because of a larger bond dissociation energy in comparison with the other two available types of hydrogens. 21 However, in a recent article by Mekarbane and Tabner, 29 hydrogen abstraction from the methyl groups in n-decane by radicals derived from di-t-butyl peroxide was observed in experiments with 2,4,6-tri-tert-butylnitrosobenzene (TTBB) as a spin trap. The results demonstrated that ϳ64% of the resulting spintrap products were derived from secondary carbon-centered radicals.…”

ESR spin-trap study of the radicals present during the thermolysis of some novel alkyl peroxy esters

“…6 -10 On the other hand, the much fasterˇ-scission of tert-amyloxyl radicals compared with tert-butoxyl radicals 10 -12 leaves the ethyl radical, a much poorer hydrogen atom abstractor, as the major initiating species. 6,9,10 Variation of R 0 (in 1) also provides a convenient means of altering activity as the thermal stability of the peroxide varies with the steric nature of both R and R 0 , decreasing as the steric bulk of these groups increases. 1 In addition to theˇ-scission of tert-alkoxyl radicals the decarboxylation of acyloxyl radicals [Scheme 1, Eqn (2)] is a well known route to alkyl radicals.…”

“…We selected the symmetric bis(3,5,5-trimethylhexanoyl) peroxide (2) in anticipation that thermolysis should initially produce two identical acyloxyl moieties (but no alkoxyl moiety) and the closely related tert-butylperoxy-3,3,5-trimethylhexanoate (3) which (during thermolysis) would be expected to produce the same acyloxyl moiety as 2 and the tertbutoxyl radical whose reactions during the thermolysis of several peroxides have been reported in detail. 6,12 The remaining two peroxides selected were tert-amylperoxy-2-ethylhexanoate (4) and the bifunctional peroxide 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane (5), both of which might be expected to produce the same acyloxyl moiety as one another.…”

“…This spin-trap can give both nitroxyl and anilino adducts the latter by attack at the oxygen atom of the nitroso group. 6,12 Unfortunately, although the number of interactingˇ-protons in anilino adducts indicate whether the original radical was a primary, secondary or tertiary C-centred species, it is difficult to obtain information on the exact structure of the original radical within each category because of the broad lines and similarity in the hyperfine parameters associated with their adducts. In addition to their broader hyperfine lines, anilino adducts are characterized by a slightly lower g-factor than that of the corresponding nitroxyl adduct.…”