Soluble polymer facilely self-grown in situ on conducting substrates at room temperature towards electrochromic applications.

Electrochromic polymer film preparation methods such as spin coating, spray coating, and electrochemical polymerization, are commonly used. At present, developing new film preparation technology is an important aspect in the field of electrochromics. Herein, a continuous in situ self-growing method based on the chemical reaction occurring on the surface of an ITO glass between a metal oxide and organic acid groups was successfully applied to prepare electrochromic polymer films at a mild room temperature. SEM, FT-IR spectroscopy, XPS, and XRD characterization methods were combined to reveal the process and mechanism of film formation. The following notable electrochromic properties were observed: switching time within 6 s, contrast reached 35%, and minimal decrease of stability after 600 cycles. Finally, the patterned films were obtained through the directional growth of polymers in solution. This study provides an effective strategy for designing and preparing electrochromic films by self-growing methods in future applications.

Reversible color modulation of luminescent conjugated polymers based on a chemical redox mechanism and applications in rewritable paper and multiple information encryption.

Reversible color modulation plays a key role in the field of information recording and encryption, but for the common colorful conjugated polymer materials, currently a convenient method to achieve their reversible color modulation is still lacking. Herein, six luminescent conjugated polymers P1 to P6 were successfully designed and synthesized, all of which could realize reversible color modulation through a similar reversible chemical redox behavior accompanied by reversible color and fluorescence changes. The same absorption spectral changes as those under electrochemical redox conditions strongly confirmed that these polymers underwent reversible redox reactions in the Fe3+ and H2O system, which happened spontaneously according to the theoretical analysis of the reaction thermodynamics. Based on the reversible color modulation in the Fe3+ and H2O system, polymers P1, P2 and P3, with different colors (yellow, orange and red) and fluorescence emissions, were successfully applied as rewritable paper with multi-color and multi-fluorescence printing as well as long-term recording capabilities. Meanwhile, polymers P1, P4, P5 and P6, which showed similar green fluorescence and yellow color but different oxidation potentials, were also introduced to accomplish multiple encryption and decryption of information, based on the step-by-step selective oxidation of the four polymers by adjusting the concentration of Fe3+.

In situ preparation and determination of electrochemical and electrochromic properties of copper phthalocyanine-polyaniline nanocomposite films.

Copper phthalocyanine (CuPc) films with different morphologies were electrodeposited on the surfaces of ITO electrodes. Then, in each case, a polyaniline (PANI) film was electrochemically polymerized in situ on the surface of the copper phthalocyanine film to form a CuPc-PANI composite film. The electrochemical properties of the CuPc-PANI composite film were observed to be much better than those of the film without CuPc. With the modification involving the CuPc nanowires, the composite film formed a finer particle surface and an increased interface area between the PANI and the electrolyte. Compared to the single-component PANI film, the CuPc-PANI composite film exhibited better performance with a higher optical contrast (58% at 730 nm), a faster response speed (coloring time of 1.02 s, discoloring time of 1.96 s), and better cycling stability (68.71% of the initial electrochemical activity after 500 cycles, in contrast to only about 48.02% for PANI). Moreover, the CuPc-PANI film shows a new feature that can be used as a supercapacitor (specifically a capacitance value of about 5.4 mF cm-2 at typical currents). Our results demonstrate that the prepared CuPc-PANI composite film is one of the best candidates for multiple potential applications such as high-performance polymer electrochromic materials and supercapacitors.