Synthesis of polyarylacetylenes by γ‐ray‐induced polymerization of terminal alkynes. Nanostructures of ortho‐substituted derivatives

Abstract

Terminal aryl alkynes RC6H4CCH with substituents of different electronic properties and ring position (R = H, 4‐CF3, 4‐OMe, 2‐CF3, 2‐OMe, 2‐Me) were exposed to γ‐radiation (50–400 kGy) in organic solvents (hexane, 1,4‐dioxane, ethylacetate, methanol, tetrahydrofuran), at room temperature. The effects arising from substituent, solvent, dilution, and radiation dose allowed to define the conditions suitable for polymerization, which was favored in methanol at increasing dilution of the alkyne. Ortho‐substitution represented the key structural element in the substrate, and the derived polyarylacetylenes were characterized in detail, including gel permeation chromatography, thermal analysis, infrared, NMR, UV–vis, fluorescence, and scanning electron microscope spectroscopy. The results are consistent with the formation of irregular polymers mainly composed of trans‐transoid chains. Controlled aggregation of the polymers by means of an osmosis‐based procedure in solvent/non‐solvent mixtures allowed the formation of nanostructured materials, in particular of hollow nanospheres from THF/water. The methodology sets the basis for the development of γ‐rays‐induced polymerization of alkynes, in a transition metal catalyst‐free environment. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

New Hyper‐Crosslinked Partly Conjugated Networks with Tunable Composition by Spontaneous Polymerization of Ethynylpyridines with Bis(bromomethyl)arenes: Synthesis, Spectral Properties, and Activity in CO2 Capture

“…Some amount of non-quaternized (pyridyl)vinylene units was admitted to be present in the linear polymers based on 2EPy and monofunctional QAs [ 37,40 ] although their formation was not involved in the mechanism of Blumstein et al The 13 C CP/MAS NMR and FTIR spectroscopy and the results of elemental analysis were used for the evaluation of the presence of the above-listed monomeric units in EPyNet1, EPyNet4, and in other polymers reported in this paper. 13 C CP/MAS NMR spectra of EPyNet1 and EPyNet4 ( Figure 1) contain a broad structured signal in the region 100-160 ppm, which corresponds to the resonance of: i) sp 2 carbons of aromatic rings of EPy and QA1 segments, and ii) sp 2 carbons of the polyene main chains. The signal at about 62 ppm corresponds to sp 3 carbons of C H 2 groups of QA1 involved in the pyridine quaternization ( C H 2 groups of N + -C H 2 -Ar segments, see Scheme 2 ).…”

“…The presence of the B-type monomeric units in EPyNet1 may be due to the diffi culties in the reaction of ArCH 2 Br pendants of units B with nitrogen of the pyridine ring that is sterically hindered by substitution in the position 2. Either absence, or only a small content (undetectable by 13 C CP/MAS NMR spectroscopy) of the B-type monomeric units in EPyNet4 refl ects the higher smoothness of the reaction of ArCH 2 Br pendants of units B with sterically unhindered nitrogen of the 4-substituted pyridine ring. The 13 C CP/MAS NMR spectra of both EPyNet1 and EPyNet4 do not contain any characteristic signals of carbons of terminal ethynyl groups (expected in the region 75-90 ppm).…”

“…The determined N:Br ratio in the polymers ( Table 2) varied from 0.98:1 to 2.31:1 and increased approximately linearly with increasing N:Br ratio in the polymerization feed (in the applied region of feed N:Br ratios). 13 C CP/MAS NMR spectra of polymers from Table 2 are given in Figure 2. Signals of terminal ethynyl carbons were not present in the spectra (i.e., none of the analyzed polymers contained C-type monomeric units) (see Scheme 2 ).…”

“…[1][2][3][4][5][6][7][8][9][10] The stepgrowth homocoupling and cross-coupling of diethynylarenes provide poly(arylenebutadiynylene)s and poly(aryleneethynylene)s, respectively. [ 1,5,6,10 ] The chaingrowth polymerization of mono-or disubstituted acetylenes results in substituted polyacetylenes [ 1,2,[11][12][13][14][15][16][17] and the polycyclotrimerization of mixtures of diethynylarenes and alkylacetylenes provides polyarylene-type polymers. [ 1,8,18 ] In the last half a decade, all of the above synthetic paths have been modifi ed for the preparation of conjugated network-type polymers.…”

Particles of polyacetylene and its derivatives: preparation and applications

“…For acetylene and the derivatives, self-assembly also can lead to some intriguing micro- 50 architectures. Bassetti, Fratoddi, Ursini et al 94 synthesized polymers from terminal alkynes by γ-irradiation. The terminal aryl alkynes RC 6 H 4 C≡C with substituents of varied electronic properties and substituting position (R = H, 4-CF 3 , 4-OMe, 2-CF 3 , 2-OMe, 2-Me, as illustrated in Figure 11) dissolved in 55 organic solvents were exposed to γ-irradiation at room temperature.…”