Hydrosilylation of diethynylbenzene with bis(dihexylsilylpropoxy)-, bis(diphenylsilylpropoxy)-, and bis(methylphenylsiloxy)-adamantane (1a, 1b, and 1c) afforded the corresponding hydrosilylated polymers. A similar reaction of bis(allyloxy)-adamantane with 1b also gave a polymer with repeating units of Ad-propylene-silanylene-propylene (Ad = adamantanediyl). Heat-resistance of the resulting polymers was examined by the thermogravimetric analysis and the highest T d5 and T d10 (temperatures of 5 and 10% weight loss) among the present polymers were noted to be 370 C and 393 C, respectively, for the polymer prepared from the reaction of diethynylbenzene with 1c. Cross-linking hydrosilylation of a vinylsiloxane polymer with 1c was also studied.KEY WORDS: Adamantane / Organosilicon Polymer / Siloxane / Hydrosilylation / Heat-Resistance / There has been interest in the synthesis of adamantane unit-containing polymers. The cage structure of adamantane allows their application as heat-resistance materials and polymers containing adamantane units as the side, 1 backbone, 2-4 and end-capping groups 5 have been reported so far. Adamantane-based epoxy resins were also reported regarding their use as encapsulants for light-emitting diode (LED).6 For the polymers with adamantane units in the backbone, poly(adamantanediyl)s were recently prepared by ring-opening polymerization of dehydroadamantane, whose thermogravimetric analysis (TGA) showed high heat-resistance properties with T d 10 (10% weight loss temperatures) of 421 C and 486 C in nitrogen for R ¼ H and Bu, respectively (Scheme 1).2 Copolymers of dehydroadamantane and vinyl compounds (AN and MA), 3 and adamantane unit-containing polyimides 4 shown in Scheme 1 were also synthesized and their heat-resistance was reported.To obtain novel adamantane-based polymers, we prepared polymers composed of repeating units of -Ad-O-Si-O-by dehydrocoupling of adamantanediol and PhSiH 3 (Scheme 1) and found that these polymers showed higher T d 10 of 512 C in nitrogen than poly(adamantanediyl)s.7 However, the polymers contained Si-OH bonds, arising from hydrolysis of the Si-H groups, which may cause disadvantages when applied to insulating films and encapsulation materials for electronic devices. For example, the Si-OH units may decrease the electric resistance of the polymer film and their condensation librating water may cause the aging deterioration. In the hope of obtaining heat-resistant adamantane unit-containing organosilicon polymers without SiOH units, we studied hydrosilylation polymerization of diethynylbenzene and bis(allyloxy)-adamantane with bis(hydrosilyl)-substituted adamantane derivatives. An application of bis(methylphenylsiloxy)adamantane prepared by dehydrocoupling of adamantanediol and PhMeSiH 2 , as a cross-linking reagent was also examined.
EXPERIMENTAL General ProcedureAll reactions were carried out in dry nitrogen. Toluene used as the reaction solvent was distilled from sodium and stored over activated molecular sieves at ambient temperature until use. Bis(ally...
Reactions of (bromophenylethenyl)diethoxysilanes with magnesium in THF gave poly[(ethoxysilylene)phenylenevinylene]s. The ethoxy group of the polymers could be readily replaced with other substituents by treating them with nucleophiles. Optical properties of the resulting poly(silylenephenylenevinylene)s were examined with respect to their UV absorption and emission spectra. Of those, pyrenylethynyl-substituted one exhibited energy transfer from the backbone to the substituent in the photo-excited state.
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