Ultrathin Conjugated Polymer Network Films of Carbazole Functionalized Poly(p-Phenylenes) via Electropolymerization

Electrodeposition and Characterization of Conducting Polymer Films Obtained from Carbazole and 2-(9H-carbazol-9-yl)acetic Acid

Electrochemical oxidation of electrolyte solutions containing carbazole (Cz) and 2-(9H-carbazol-9-yl)acetic acid (CzA) monomers was performed in acetonitrile solutions. Different Cz and CzA feed ratios were used to electrodeposit solid polymer films of various compositions, and to study the influence of the monomer ratio on the physicochemical properties (electroactivity, topography, adhesion, stiffness, wettability) of the polymer films. Thus, electrochemical oxidation led to the deposition of a solid film of micrometric thickness, but only for the solutions containing at least 30% of Cz. The proportion of Cz and CzA in the electrodeposited polymer films has little impact on the adhesion strength values measured by AFM. On the contrary, this proportion significantly modifies the stiffness of the films. Indeed, the stiffness of the polymer films varies from 9 to 24 GPa depending on the monomer ratio, which is much lower than the value obtained for unmodified polycarbazole (64 GPa). This leads to the absence of cracks in the films, which all have a fairly homogeneous globular structure. Moreover, among the different polymer films obtained, those prepared from 70:30 and 50:50 ratios in Cz:CzA monomer solutions seem to be the most interesting because these green films are conductive, thick, low in stiffness, do not show cracks and are resistant to prolonged immersion in water.

Reversible Charge Trapping in Bis-Carbazole-Diimide Redox Polymers with Complete Luminescence Quenching Enabling Nondestructive Read-Out by Resonance Raman Spectroscopy

The coupling of substituted carbazole compounds through carbon-carbon bond formation upon one-electron oxidation is shown to be a highly versatile approach to the formation of redox polymer films. Although the polymerization of single carbazole units has been proposed earlier, we show that by tethering pairs of carbazoles double sequential dimerization allows for facile formation of redox polymer films with fine control over film thickness. We show that the design of the monomers and in particular the bridging units is key to polymer formation, with the diaminobenzene motif proving advantageous, in terms of the matching to the redox potentials of the monomer and polymer film and thereby avoiding limitations in film thickness (autoinsulation), but introduces unacceptable instability due to the intrinsic redox activity of this moiety. The use of a diimide protecting group both avoids complications due to p-diamino-benzene redox chemistry and provides for a redox polymer in which the photoluminescence of the bis-carbazole moiety can be switched reversibly (on/off) with redox control. The monomer design approach is versatile enabling facile incorporation of additional functional units, such as naphthalene. Here we show that a multicomponent carbazole/naphthalene containing monomer (APCNDI) can form redox polymer films showing both p- and n- conductivity under ambient conditions and allows access to five distinct redox states, and a complex electrochromic response covering the whole of the UV/vis-NIR spectral region. The highly effective quenching of the photoluminescence of both components in poly-APCNDI enables detailed characterization of the redox polymer films. The poly-APCNDI films show extensive charge trapping, which can be read out spectroscopically in the case of films and is characterized as kinetic rather than chemical in origin on the basis of UV/vis-NIR absorption and resonance Raman spectroscopic analyses. The strong resonantly enhanced Raman scattering for the various oxidized and reduced states of APCNDI enables nondestructive "read-out" of the state of the polymer, including that in which charges are trapped kinetically at the surface, making poly-APCNDI highly suitable for application as a component in organic nonvolatile memory devices.

Simultaneous doping and crosslinking of polythiophene films

We present a click chemistry approach for the synthesis of conjugated redox polymers based on highly regioregular polythiophenes with tunable amounts of pendant redox-active triphenylamine (TPA) groups. Solution-deposited films can be simultaneously doped and crosslinked by electrochemical or chemical oxidation.

Benzoyl Peroxide Oxidation Route to the Synthesis of Solvent Soluble Polycarbazole

Carbazole was oxidized by benzoyl peroxide in presence of p-toluenesulfonic acid to polycarbazole salt at room temperature for the first time. Polycarbazole salts were synthesized via solution and emulsion polymerization pathways. Polycarbazole bases were prepared by dedoping from polycarbazole salts. Formation of polycarbazoles was confirmed from infrared, electronic absorption and EDAX spectra. Polycarbazole salt was obtained in amorphous nature in semiconductor range (10(-5) S/cm), which was found to be soluble in less and high polar solvents. Polycarbazole salt prepared by emulsion polymerization pathway showed mixture of shapes with microrod, sphere, and pores, whereas its corresponding base showed only micropores structure. On the other hand, polycarbazole salt and its corresponding base prepared by solution polymerization pathway showed flake-like morphology. Higher thermal stability was obtained for polycarbazole salt prepared by emulsion polymerization pathway than that of the salt prepared by solution polymerization pathway.

Conjugated polymer network films of poly(p-phenylene vinylene) with hole-transporting carbazole pendants: dual photoluminescence and electrochromic behavior

A series of poly(p-phenylene vinylene) (PPV) copolymers functionalized with hole-transport and electrochemically active carbazole units as pendant moieties is reported. These polymers exhibit photoluminescence properties by virtue of the PPV analogous backbone. They were also designed as precursor polymer bearing the electroactive carbazole group to form conjugated polymer network (CPN) films by electrodeposition. The electrochemical polymerization of the pendant units eventually lead to a dual property electro-optically active thin film - photoluminescence (PL) behavior that can be attenuated with CPN formation, and a reversible doping and dedoping processes at controlled potentials that lead to an electrochromic behavior. This reveals the ability to incorporate complementary optical and electro-optical properties within the same film using the CPN approach. It should be possible to design and synthesize other PPV π-conjugated polymers with efficient pendant hole-transport groups exhibiting tunable PL and electrochromism with cross-linking.

1,4-Dibut-oxy-2,5-bis-{(Z)-2-[4-(9H-carbazol-9-yl)phen-yl]ethen-yl}benzene

The title compound, C(54)H(48)N(2)O(2), lies about an inversion centre. The carbazole ring system makes dihedral angles of 58.43 (7) and 88.96 (7)°, respectively, with the adjacent and central benzene rings. The dihedral angle between the two benzene rings is 52.01 (8)°. In the crystal, mol-ecules are linked by pairs of C-H⋯O inter-actions, forming a tape along the a axis. The methyl group is disordered over two sets of sites with occupancies of 0.63 (3) and 0.37 (3).

Colloidally templated two-dimensional conducting polymer arrays and SAMs: binary composition patterning and chemistry

A facile approach and strategy toward binary-composition, two-dimensional (2D) patterned surfaces of conducting polymer periodic arrays, together with thiol self-assembled monolayers (SAMs) is described. The method involved a Langmuir-Blodgett (LB)-like deposition of latex microsphere particles, electropolymerization via cyclic voltammetric (CV) techniques, and self-assembly of an amphiphile. The LB-like technique enabled the monolayer deposition of different sizes of polystyrene (PS) particles in hexagonal packing arrangement on planar substrates. Combining the LB-like method with CV electropolymerization is advantageous because it provides deposition control of a polymer interconnected network, controlled composition ratio of polymer and SAMs, and control of 2D size and spacing of the spherical void pattern. Electrochemical-quartz crystal microbalance (EC-QCM) in situ monitoring of the film deposition quantified a constant and linear growth rate, with varying viscoelastic behavior of the conducting polymer adsorption on planar and PS-templated substrates. The dual-patterned surface provided a good imaging contrast as observed by atomic force microscopy (AFM). Complementary analyses such as X-ray photoelectron spectroscopy (XPS), attenuated total internal reflection infrared (ATR IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, and static contact angle measurements were used to characterize the formation of the patterned surface. The versatility of the method enables the potential for making various types of quantitative binary compositions and patterned surfaces using different combinations of conducting polymer or functional SAMs, which can be extended in the future to polymer brushes and layer-by-layer assembly of various materials.

Intercalative poly(carbazole) precursor electropolymerization within hybrid nanostructured titanium oxide ultrathin films

A protocol for nanostructuring and electropolymerization of a hybrid semiconductor polycarbazole-titanium oxide ultrathin film is described. Ultrathin (<100 nm) films based on polycarbazole precursor polyelectrolytes and titanium oxide (TiOx) have been fabricated by combining the layer-by-layer (LbL) and surface sol-gel layering techniques. Film growth was followed and confirmed through UV-vis spectroscopy, ellipsometry and quartz crystal microbalance with dissipation (QCM-D). Subsequent anodic electrochemical oxidation of the carbazole pendant units afforded a conjugated polymer network (CPN) film within intercalating TiOx layers of cross-linked and π-conjugated carbazole units. Cyclic voltammetry (CV), UV-vis, and fluorescence spectroscopy measurements confirmed this process. The LbL-driven polyelectrolyte deposition process resulted in a quantified electrochemical response, proportional to the number of layers, while the TiOx acted as a dielectric spacer limiting electron transfer kinetics and attenuating energy transfer in fluorescence. Electro-optical properties were compared with other polycarbazole thin film materials with respect to bandgap energy (Eg). The straightforward protocol in film nanostructuring and barrier/dielectric properties of the inorganic oxide slab (denoted here as, TiOx) should enable applications in organic light-emitting diodes (OLEDs), dielectric mirrors, planar waveguides, and photovoltaic devices for these hybrid ultrathin films.

Electropolymerization molecularly imprinted polymer (E-MIP) SPR sensing of drug molecules: pre-polymerization complexed terthiophene and carbazole electroactive monomers

A novel chemosensitive ultrathin film with high selectivity was developed for the detection of naproxen, paracetamol, and theophylline using non-covalent electropolymerized molecular imprinted polymers (E-MIP). A series of monofunctional and bifunctional H-bonding terthiophene and carbazole monomers were compared for imprinting these drugs without the use of a separate cross-linker. A key step is the fast and efficient potentiostatic method of washing the template, which facilitated enhanced real-time sensing by surface plasmon resonance (SPR) spectroscopy. Various surface characterizations (contact angle, ellipsometry, XPS, AFM) of the E-MIP film verified the templating and release of the drug from the cross-linked conducting polymer film.