In this work, we describe the synthesis and electropolymerization of conjugated substituted polyacetylenes, poly(N-alkoxy-(p-ethynylphenyl)carbazole) or PPA-Cz-Cn with electropolymerizable carbazole side groups to form conjugated polymer network (CPN) films. The phenylacetylene monomer was functionalized with a carbazole group separated by an alkylene spacer. Polymerization of the monomer in solution is accomplished using a Rh catalyst to form a “precursor polymer”. The electrochemical behavior and cross-linking of the carbazole side group was then investigated by cyclic voltammetry (CV) and spectroelectrochemistry. A trend in the redox electrochemical behavior was observed with varying alkyl spacer length between the poly(phenylacetylene) backbone and carbazole side-group. The resulting film combines the electrooptical properties of the conjugated poly(phenylacetylene) polymer with polycarbazole units in a cross-linked electropolymerized film as evidenced by the CV and spectroelectrochemical behavior. This study emphasizes the preparation of polymer materials with mixed π-conjugated species arising from the electrochemical cross-linking of a designed precursor polymer.

The stability of poly(phenylacetylene)s in solution was systematically studied. Cis–transoidal poly(phenylacetylene) prepared with a Rh catalyst readily underwent autoxidative degradation into oligomers, whereas a W‐based polymer with a trans‐rich geometrical structure degraded slowly under similar conditions. The degradation of W‐based poly(phenylacetylene) was independent of the solvents, whereas the degradation of the cis–transoidal material strongly depended on the solvents, and very rapid degradation was observed in toluene and CHCl3. A reduction in the degradation rate in the absence of oxygen and the appearance of carbonyl groups in an IR spectrum and aldehyde protons in a 1H NMR spectrum of the resulting oligomers indicated the direct participation of oxygen in the degradation where light was supposed to assist the degradation by producing radicals on the main chain. The cis content of cis–transoidal poly(phenylacetylene) was unchanged during the degradation, unlike for the acid‐catalyzed decomposition, in which the cis content decreased linearly as the molecular weight decreased. Ring‐substituted poly(phenylacetylene)s degraded slowly compared with poly(phenylacetylene), regardless of the kind of substituent, which suggests that steric factors affected the degradation rate. The use of radical scavengers such as 2,2,6,6‐tetramethylpiperidine‐1‐oxyl and diphenylpicrylhydrazil suppressed the decomposition. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3130–3136, 2001

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Azobenzene-containing polyacetylenes, poly[(4-butoxyphenyl)(4-ethynylphenyl)diazene] [poly(BuOEAB)] and poly[4-(4-ethynylphenylazo)benzoic acid hexyl ester] [poly(HexOCOEAB)] with number-average molecular weights ranging from 2,800 to 104,000 were synthesized by the polymerization of the corresponding acetylene monomers by [RhCl(norbornadiene)] 2 catalyst in conjunction with Et 3 N, Ph 2 CC(Ph)Li, and PPh 3 as cocatalysts in toluene and THF in good yields. The polymers exhibited thermogravimetric curves with in¯ection points corresponding to cleavage of butyl ether and hexyl ester groups. The trans-azobenzene moiety of poly(BuOEAB) isomerized into cis-form upon UV-irradiation at the wavelength of 300À400 nm both in solution and in the ®lmy state. On the other hand, poly(HexOCOEAB) did not isomerize under the same condition.

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Acetylenes containing salicylideneaniline groups—N‐salicylidene‐3‐ethynylaniline (1), N‐(3‐t‐butylsalicylidene)‐3‐ethynylaniline (2), and N‐(3‐t‐butylsalicylidene)‐4‐ethynylaniline (3)—polymerized smoothly and gave yellow to red polymers in excellent yields when a rhodium catalyst was employed. Polymers with alkyl substituents on the aromatic rings [poly(2) and poly(3)] were soluble in CHCl3, tetrahydrofuran, and so forth, whereas the polymer without alkyl substituents [poly(1)] was insoluble in any solvent. N‐(3‐t‐Butylsalicylidene)propargylamine did not provide any polymer. Thermogravimetric analyses of the resultant polymers exhibited good thermal stability (To, onset temperature of weight loss > 300 °C). The ultraviolet–visible spectra of the polymers showed absorption maxima and cutoff wavelengths around 360 and 520 nm, respectively. The polymers exhibited largely Stokes‐shifted fluorescence (emission wavelength ≃ 550 nm) upon photoexcitation at 350 nm, which resulted from the photoinduced intramolecular proton transfer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2458–2463, 2002