Solubilization of Regioregular and Regioirregular Poly(p-phenylene)s via CF₃ and OCF₃ Substituents To Generate a Model for Rigid-Rod Polymers

Abstract

Regioirregular poly(p-phenylene)s (PPPs) with OCF3, CF3 or OCH3 substituents (16a, 16b, or 16c, respectively) were synthesized via Ni(0)-catalyzed polymerization of 2-substituted-1,4-bis-[[(trifluoromethyl)sulfonyl]oxy]benzenes (5, 8, or 10, respectively). Regioregular head-to-head PPPs with OCF3 or CF3 substituents (17a or 17b) were prepared from 2,2′-disubstituted-4, 4′-bis[[(trifluoromethyl)sulfonyl]oxy]biphenyls 14a, 14b and 2,2′-disubstituted-4,4′-bis[methylsulfonyl)oxy]biphenyls 15a, 15b. Regioregular head-to-head statistical copolymers with combinations of OCF3 or CF3 substituents with OCF3, CF3, CO(p-FC6H5), CH3, or H substituents (17xy) were synthesized by the copolymerization of 15a or 15b with 2,2′-disubstituted-4,4′-bis[(methylsulfonyl)oxy]biphenyls 15a-15e. Regioirregular and regioregular PPPs with OCF3 or CF3 substituents were soluble (THF, CHCl3, dipolar aprotic solvents). The highest molecular weight PPPs were obtained from OCF3-substituted monomers. Regioirregular PPP (16a) with Mn ) 35 200 (corresponding to 220 phenylene groups relative to polystyrene standards) was obtained from 5. Regioregular PPP (17a) with Mn ) 54 500 (340 phenylene units) was obtained from 14a. Regioregular PPP copolymers (17ab) with Mn ) 55 200 (363 phenylene units) were obtained from copolymerization of 15a and 15b. The λmax values of OCF3-and CF3-substituted PPPs were 302-307 and 273-271, respectively. A 10% weight loss occurs in the range of 550-575 °C for PPPs with OCF3 substituents and 580-615 °C for those with CF3 substituents. Polymers 17a, 17b, and 17ab exhibit enantiotropic nematic and lyotropic mesophases. The thermotropic nematic phase of 17a, 17b, and 17ab is stable up to the decomposition temperature. Most probably, 17a and 17b also exhibit a second mesophase which is monotropic and becomes enantiotropic in 17ab. The rigid-rod character of these polymers was demonstrated by the Mark-Houwink coefficient a ) 1.58-1.60. Phosphorus was not detected (MALDI and 31 P NMR) in the structure of these homopolymers and copolymers.

Synthesis of π-Conjugated Polymers Bearing Electronic and Optical Functionalities by Organometallic Polycondensations. Chemical Properties and Applications of the π-Conjugated Polymers

“…31 Use of C-OY (Y = tosyl, etc.) compounds, instead of C-X compounds (OY = leaving group or pseudo-halogen), is also possible for the polycondensation (Scheme 2), 31,50 which is considered to proceed through oxidative addition of C-OY to a transition metal which was studied previously by us. [98][99][100] Scheme 2…”

Alkyl-substituted poly(2,5-benzophenone)s synthesized via Ni(0)-catalyzed coupling of aromatic dichlorides and their miscible blends

“…The deviation from the expected value of 2.0 is consistent a broad range of polydispersities previously reported for similar materials made via Ni(0)-catalyzed coupling polymerization. 8,9,18 Further work is planned to investigate the origin of the varying polydispersities of these materials. The polymers have approximately the same intrinsic viscosity ([]) of 0.52 dL/g (NMP, 30°C).…”

“…[5][6][7] Appropriately substituted materials are soluble and yet exhibit thermal and mechanical properties comparable to the unsubstituted polymer. Percec et al 8,9 have recently synthesized a variety of soluble polyphenylenes by the Ni(0)-catalyzed coupling of bis(aryl mesylates). The resulting polymers are high molecular weight, soluble, and thermally stable.…”

Pyrolysis of polyphenylenes with PCL or/and PSt side chains

“…The direct synthesis of derivatized para-substituted PP and other soluble polyarylenes are primarily based upon nickel-and palladium-mediated cross-coupling reactions [12] largely due to their preservation of regiochemistry and nearly quantitative yields [5,12,13]. One of the most common methods for the synthesis of polyarylenes [14] is the cross-coupling of aryl halides and aryl boronic acids (Suzuki coupling) [11] that has several advantages, such as simplicity of the procedure and insensitivity of the reaction to moisture.…”