Ring-Opening Polymerizations of 1,3-Dehydroadamantanes: Synthesis of Novel Thermally Stable Poly(1,3-adamantane)s

Abstract

Ring-opening polymerization of 1,3-dehydroadamantanes (DHAs) such as 1,3-dehydroadamantane (1), 5-butyl-1,3-dehydroadamantane (2), and 5,7-dibutyl-1,3-dehydroadamantane (3) was carried out under various conditions. Poly­(1,3-adamantane)­s were quantitatively obtained by thermal polymerization of DHAs in bulk. Radical polymerization of DHAs with α,α′-azobis­(isobutyronitrile) (AIBN) proceeded in bulk at 80 °C. By contrast, virtually no reactions of DHAs occurred with n-BuLi in n-heptane and phenylmagnesium chloride in tetrahydrofuran (THF), indicating their negative anionic polymerizability. On the other hand, cationic ring-opening polymerization of DHAs smoothly proceeded with super Brønsted acids such as trifluoromethanesulfonic acid (TfOH) or trifluoromethanesulfonimide (Tf2NH) to afford corresponding polymers in good to quantitative yield. Although Tf2NH induced rapid polymerization of DHAs even at −78 °C, higher temperatures such as 0 or 30 °C were necessary to initiate polymerization with TfOH. In the presence of Lewis bases such as ethyl acetate, diethyl ether, or THF, retardation of cationic polymerization was apparently observed, indicating nucleophilic interaction of added bases toward a propagating 1-adamantyl cation derived from DHAs. The resulting poly­(2) bearing a flexible n-butyl group was soluble in various solvents, while highly symmetrical poly­(1) and poly­(3) showed very poor solubility. The M n value of the cationically obtained poly­(2) reached 6900, and the degree of polymerization was estimated to be greater than 30. The resulting poly­(1,3-adamantane)­s showed high thermal stability in thermogravimetric analysis (TGA), and the 10% weight loss temperatures of poly­(1), poly­(2), and poly­(3) were respectively 480, 488, and 477 °C. Poly­(2) and poly­(3) exhibited a glass transition temperature (T g) at 205 and 139 °C, respectively, in differential scanning calorimetry (DSC) measurements.

Template Synthesis of Linear‐Chain Nanodiamonds Inside Carbon Nanotubes from Bridgehead‐Halogenated Diamantane Precursors

“…Thep resent templatebased approach for the synthesis of linear-chain diamondoid polymers is entirely different from conventional chemical approaches. [22,[33][34][35][36] We have also developed am ethod for extracting the products formed inside the CNT templates from the template through solution-phase sonication/extraction. [37] Studies on polymer extraction are currently in progress to investigate their tensile strengths or thermal transport properties.W ea lso expect that the present template-based approach will provide access to adiverse range of novel 1D polymers.I np rinciple,t he present strategy is applicable to various dihalogen-substituted molecules.Infact, preliminary experiments indicate that the polymerization can also occur with other precursor molecules.T he present synthetic method may offer an ew strategy for the design and synthesis of one-dimensional nanomaterials.…”

Synthesis of high‐performance polyurethanes with rigid 5‐6‐5‐fused ring system in the main chain from naturally occurring myo‐inositol

“…INTRODUCTION Development of monomers with highly rigid structures and their use in polymerizations is a promising approach to high-performance polymer materials that exhibit excellent heat resistance and mechanical strength. [1][2][3][4][5][6] Bifunctional monomers involving diols bearing nonaromatic and rigid cyclic cores with conformational restriction are of high interest because of their facile and versatile applications to polycondensation and polyaddition systems that permit diverse designs of high-performance polymers. 7,8 Recently, derivation of sugars into conformationally rigid monomers via selective transformation of their functional groups has gained increasing interest, because this strategy meets the current demands for polymer synthesis from nonfossil and renewable feed stocks.…”

Template Synthesis of Linear‐Chain Nanodiamonds Inside Carbon Nanotubes from Bridgehead‐Halogenated Diamantane Precursors

“…[22,[33][34][35][36] We have also developed am ethod for extracting the products formed inside the CNT templates from the template through solution-phase sonication/extraction. Thep resent templatebased approach for the synthesis of linear-chain diamondoid polymers is entirely different from conventional chemical approaches.…”