Effect of aromatic protectors on the radiolysis of polyorganosiloxanes

Polyphenylsilsesquioxanes. New structures–new properties

“…The phenyl radical at the silicon atom gives these compounds enhanced thermal and radiation stability. 3 In combination with excellent dielectric properties, hydrophobicity and solubility, this allows them to be widely used as protective coatings for electronic devices. 4 based on commercial varnishes based on phenylsilsesquioxane (or its copolymers with difunctional monomers) ensure longterm operation of devices under high humidity conditions at 250-300 C. 6 The optical transparency and high refractive index make polyphenylsilsesquioxanes attractive objects for optics and optoelectronics.…”

Is energy transfer through the siloxane chain (-Si-O-) possible?

“…However, a considerable difference was revealed in the effects of phenyl groups on radiation crosslinking processes in polymethylphenylsiloxane homopolymers and polyphenylsilsesquioxane block copolymers (BCPs) at equal concentrations of methyl and phenyl groups. In BCPs, the effect of crosslinking was much greater than that in the polymethylphenylsiloxane homopolymers [3]. Thus, the protective effect of phenyl groups in BCPs is much weaker because of the localization of phenyl groups in the hard polydimethylphenylsilsesquioxane block, although both dimethylsiloxane and phenylsilsesquioxane blocks are linked by -Si-O-Si-bonds.…”

“…(2) In the irradiation of a 0.001 M BCP 2080 solution in cyclohexane, the radiation-chemical yield G of decay of phenyl groups was equal to 1.8 per 100 eV of energy absorbed by the solution or 6.5 × 10 3 per 100 eV of energy absorbed by phenyl groups [3]. The UV absorption spectrum exhibited the smearing of the envelope of phenyl chromophore bands and a decrease in the band intensity at ~260 nm, which are indicative of the transformation of phenyl groups.…”

Ablation and Deposition of Poly(dimethylsiloxane) with X‐Rays

“…For instance, electron irradiation, revealed by Miller as early as 1960, causes SiÀCH 3 and SiCH 2 ÀH scissions, generating H 2 , CH 4 , and C 2 H 6 as gaseous products. [10,11] Despite the well-established radiation chemistry of PDMS, there are few reports to demonstrate highly efficient wettability changes in PDMS using ionizing radiation.From studies on various soft matter and inorganic systems using hard X-rays (10-60 keV), [12,13] we recently developed an X-ray ablation technique using rapid depolymerization of organic polymers.[14] Here our results of PDMS demonstrate that X-ray irradiation is a highly efficient and feasible protocol for surface modification through PDMS ablation. The X-ray-induced ablation enables one not only to oxidize the PDMS surface (hydrophilicity) but also to deposit the ablated PDMS (hydrophobicity) on other hydrophilic surfaces.…”

“…[10,11] The most important benefit of the X-ray-induced ablation process is its capability to generate hydrophobic molecules that can be efficiently deposited on adjacent hydrophilic surfaces. The PDMS-deposited glass surface can then be altered to be hydrophobic.…”