Photodegradation and electron-beam-induced degradation of poly[(pentamethyldisilyl)styrene sulfones]

Abstract

Photodegradation and electron-beam-induced degradation of poly[(pentamethyldisilyl)styrene sulfonels were investigated by flash and pulse radiolysis techniques. The transient absorption spectra obtained by the flash photolysis for the solution of nonaltemating poly [(pentamethyldisilyl)styrene sulfonels in THF (tetrahydrofuran) showed the formation of benzyl radical as a transient intermediate. On the other hand, the transient absorption spectra for an alternating poly [(pentamethyldisilyl)styrene sulfone] did not show the absorption of benzyl radical but showed that of p-(pentamethyldisilyl)styrene monomer. The decay curve for an alternating poly [ (pentamethyldisilyl) styrene sulfone] exhibited fast depropagation after the flash photolysis. The disilyl bond in the polymer dissociates easily by photolysis whereas the bond was stable under electron-beam irradiation. The transient absorption spectra of a radical anion of the sulfonyl group was observed by pulse radiolysis for the solution of poly[(pentamethyldisilyl)styrene sulfonels in THF.

Oxidant‐Dependent REDOX Responsiveness of Polysulfides

“…Two sets of peaks can be recognized (left inset in Figure 7), which can be ascribed to structures (S A to S D ) compatible with alkylene sulfone depolymerization because they feature terminal double bonds and sulfinic acids. This is not a surprising phenomenon because aliphatic polysulfones [poly(alkenyl sulfones)] are well known to depolymerize under mild conditions: the weak C—S bond can be easily cleaved thermally44 or via irradiation (e.g., X‐rays45, 46 or electron beams47), releasing ultimately SO 2 and olefins. It is unclear whether the observed reduction in molecular weight can be ascribed to depolymerization occurring during oxidation, or to a fragmentation during MALDI‐TOF analysis.…”

Poly(olefin sulfone)s

“…The unzipping degradation of a polymer main chain containing heteroatoms by X-ray or electron-beam irradiation has been achieved. For a poly(1-butene sulfone), only partial depolymerization occurs, and olefins are present in the gas produced by the irradiation [11,12].…”

Photoinduced Depolymerization of Poly(olefin sulfone)s Possessing Photobase Generating Groups in the Side Chain

“…It has been known that in the case of a poly-(1-butene sulfone), a partial depolymerization occurs, and olefins are involved in the gas produced by γ-rays or electron-beam irradiation. 11,12 A poly(olefin sulfone) possesses sulfonyl groups (-SO 2 -) in the main chain, and they are easily synthesized by radical polymerization of an olefin monomer in a liquefied sulfur dioxide. 13,14 The olefin radical is unstable; however, the sulfonyl radical is fairly stable.…”

“…However, most depolymerizable polymers known so far require γ-rays or electron beam irradiation for the depolymerization process. , There are only a few that are known to exhibit depolymerization by low-energy irradiation. − The unzipping degradation of a polymer main chain by irradiation was achieved in polymers containing heteroatoms in a main chain. It has been known that in the case of a poly(1-butene sulfone), a partial depolymerization occurs, and olefins are involved in the gas produced by γ-rays or electron-beam irradiation. , A poly(olefin sulfone) possesses sulfonyl groups (−SO 2 −) in the main chain, and they are easily synthesized by radical polymerization of an olefin monomer in a liquefied sulfur dioxide. , The olefin radical is unstable; however, the sulfonyl radical is fairly stable. The olefin radical generated in liquefied sulfur dioxide immediately reacts with a sulfur dioxide molecule and results in an alkylated sulfonyl radical.…”