HCID 178420039, compound → Carbazole

Another embodiment of the present invention discloses the electrochemical deposition, characterization, and spectroscopic analysis of nanocomposite films made of PVK/MWNTs or π-conjugated polymer network (CPN). FIG. I.6 describes the cyclic voltammograms recorded on Au electrode spin-coated with PVK and PVK/MWNTs nanocomposite in 0.1 M LiClO4 in ACN at different scan rates; (a) pure PVK, (b) 97% PVK/3% MWNTs, (c) 95% PVK/5% MWNTs, and (d) 93% PVK/7% MWNTs. In all cases the 1st cyclic voltammogram is presented. Potentials are reported against Ag/AgCl reference electrode. CV electrodeposition, cross-linking and characterization of the prepared PVK (control) and PVK/MWNTs nanocomposite films are done in 0.1 M LiClO4 in ACN with potential scans from 0-1.2 V. The solutions prepared as described previously are spin-casted on the ITO glass substrate and in Au substrate to directly measure the thickness of the film. Note that the spin-coated films are insoluble to ACN. FIG. 6 shows the cyclic voltammograms of pure PVK scanned at 50 mV/s for 50 cycles and PVK/MWNTs films at different scan rates in order to cross-link the PVK film forming the π-conjugated polymer network (CPN) film (FIG. 6). For pure PVK, an irreversible oxidation peak at about 0.9-1.0 V and reduction peak at 0.7 V is observed in the voltammogram which suggest the formation of the of carbazolylium radical cation, and a cross-linked material having a higher electrical conducting behavior compared to the PVK precursor. This essentially represents the formation of a CPN control film. FIG. 7 depicts the cyclic voltammograms recorded on ITO glass electrode spin-coated with (A) pure PVK and (B) 97% PVK/3% MWNTs CPN film in 0.1 M LiClO4 in ACN at 50 mV/s for 50 cycles. Potentials are reported against Ag/AgCl reference electrode. The scan rate dependence studies for pure PVK at scan rates 10-200 mV/s was also investigated. The current of the oxidation/reduction peaks are dependent on scan rates in the range of 50-200 mV/s (FIG. 6). The electron transfer rate depends on the electron transfer resistance across the electrode/conductive polymer/electrolyte layer model. The shapes of the voltammogram are different when the MWNTs are added to the electrochemically cross-linkable PVK. A downshift in the reduction peak is observed for PVK/MWNTs and this could be due to the doping behavior of the negatively charged MWNTs. No anodic peak is observed regardless of the number of cycles employed on the PVK/MWNTs film deposited in ITO glass substrate. The electrochemical cross-linking of PVK and MWNTs carried out at different voltage scan rates shows a good correlation with the cathodic peak current and voltage scan rate indicating that the electron transfer is diffusion controlled. The observed correlation is in agreement with the EIS analysis as will be discussed further. With increasing number of cycles recorded for the PVK/MWNTs nanocomposites, a gradual shift in peak potentials for the reduction peaks is indicative of the doping role of MWNTs which would assume a negative charge. Such a down-shift in the cathodic peak could be due to the doping role of MWNTs, which are known to be amphoteric in character (can be doped with either electron donor or acceptor). Taking into account in this CPN nanocomposite films the PVK acting as electron donor and MWNTs which act as the electron acceptor. Note that CV is used herein as a representative method among other existing potentiodynamic electropolymerization methods. Other potentiostatic methods or constant potential electropolymerization methods can be used to achieve the same or a similar goal. Similarly a chemical oxidant such as, but not limited to FeCl3 or NH4S2O8 or other oxidizing agents can be used for polymerization, the common mechanism being the formation of a radical cation during the polymerization process. Therefore as an alternative method based on prior art, the use of a chemical oxidant to provide for the reaction of carbazole (or other electro-active monomer units) via a radical cation coupling mechanism can be employed. This can involve the spin-coating or casting of the solution to a non-conducting or conducting (electrically) substrate followed by drying. The dried film is then treated to a solvent (immiscible to the film) containing the chemical oxidant. This will result in a similar polymerization mechanism and conversion of the precursor to a conjugated polymer network composite.

1. customThe solutions prepared
2. customforming the π-conjugated polymer network (CPN) film (FIG. 6)
3. additionare added to the electrochemically cross-linkable PVK
4. temperatureWith increasing number of cycles
5. customcan be used for polymerization

ORD record

ord-0a6a0437b83746fe94a6d63d66e868af

Source dataset

uspto-grants-2015_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08932671B2