On the formation of polyacetylenes and cyanopolyacetylenes in Titan's atmosphere and their role in astrobiology

Abstract

This tutorial review compiles recent experimental and theoretical studies on the formation of polyacetylenes (H(C≡C)(n)H) and cyanopolyacetylenes (H(C≡C)(n)CN) together with their methyl-substituted counterparts (CH(3)(C≡C)(n)H, CH(3)(C≡C)(n)CN) as probed under single collision conditions in crossed beam studies via the elementary reactions of ethynyl (CCH) and cyano radicals (CN) with unsaturated hydrocarbons. The role of these key reaction classes in the chemical evolution of Titan's orange-brownish haze layers is also discussed. We further comment on astrobiological implications of our findings with respect to proto-Earth and present a brief outlook on future research directions.

Particles of polyacetylene and its derivatives: preparation and applications

“…Moreover, since the investigated polymer chains could form helical conformations, as justified in earlier studies, 66-68 the polymers 25 obtained by emulsion polymerization were further explored for elucidating the secondary structures of the polymer chains. Both CD (circular dichroism) and UV-vis absorption spectra demonstrated that in all the four polymer particles obtained via emulsion polymerization approach, the polymer chains adopted 30 helical structures, just as expected. It is further found that the emulsion polymerization, when compared to the corresponding solution polymerization, is much more beneficial for the polymer chains to take helical conformations with predominantly onehanded helicity.…”

“…In the first case, successfully utilized heterophase polymerization methods include emulsion, suspension, precipitation, and dispersion polymerization techniques and the respective derivatives. Among the methods, emulsion 30 polymerization techniques seem to be the most widely used one. In the second case, i.e.…”

“…2-hydroxyethyl methacrylate (HEMA). 57 In the course of polymerization, KPS introduced charged species which were helpful to improve the colloidal stability and 30 monodispersity. For HEMA, it is a polar monomer and could be attached on the surface of the formed polymeric particles due to its hydrophilic nature, by which also to improve the colloidal stability in aqueous media.…”

“…[10][11][12] Continuous microfluidic reactors were also used for preparing polymer particles. 13 However, a majority of the polymer particles currently under investigation are limited to vinyl polymer derivatives, 30 which have been reviewed extensively. [1][2][3][4][5][6]14 In sharp contrast to this situation, particles of polyacetylene and the derivatives, although historically taken as typical conjugated polymers, have been little addressed.…”

“…The first study on polyacetylene began approximately one half century ago, and so far series of exciting achievements have been 40 made in fundamental research; [19][20][21][22][23][24][25][26][27][28][29][30][31][32] however the progress in practical applications of polyacetylenes is far from being satisfying. The major reason for this terrible situation is attributed to the limitations of polyacetylene and a considerable part of the derivatives, i.e.…”