This journal is © the Owner Societies 2016 Phys. Chem. Chem. Phys., 2016, 18, 21659--21667 | 21659 Cite this: Phys. Chem. Chem. Phys.,
2016, 18, 21659
Smart windows application of carbazole and
triazine based star shaped architecture
Merve Guzel, Tugba Soganci, Rukiye Ayranci and Metin Ak*
A novel triazine-based, star shape and electroactive monomer, 2,4,6-tris(yl)ethoxy)-1,3,5-triazine (TCZ) which contains 2,4,6-trichloro-2,4,6-tris(yl)ethoxy)-1,3,5-triazine as the core and 2-(9H-carbazol-9-yl)ethanol as the arms, was successfully synthesized. After electrochemical polymerization of the TCZ monomer, called PTCZ, the polymer shows superior optoelectronic and thermal properties due to its unique three-dimensional shape and highly-branched structure in comparison with linear analogues. Electrochromic studies exhibited that PTCZ has turquoise color in the oxidized state and is transparent in the neutral state. Due to the fact that the redox color characteristics of PTCZ are indispensable for smart windows, a PTCZ-based electrochromic device was formed with PEDOT as complementary coloring material. A potential range of 1.5 to +1.8 V was determined to be suitable for operating the PTCZ/PEDOT device between transparent and blue colors. Characterizations of the device were performed in term of switching times, optical contrast, optical memory and redox stability.
Introduction
During the past several decades star shape polymer derivatives containing the 1,3,5-triazine1–3ring have become the focus of intensive research and development. These molecules indicate a wide importance in optoelectronics owing to their perfect semiconducting and photophysical properties as well as electro-chemical characteristic.4,5 Moreover, the 1,3,5-triazine unit possesses structural symmetry and high electron affinity.6This makes them promising materials for several applications such as light-emitting devices (LED), chemiresistors, electrochromic devices (ECDs)7–10and sensors.11–13Electrochromism is a reversible and visible change in transmittance and/or reflectance that is coupled with an electrochemically induced oxidation–reduction reaction.14–16Recently, the use of these conducting polymers in various fields has led to some advantages.17–21These advantages include not only multicolors and high fluorescence yield22,23but also fast switching capability and excellent thermal stability.24–26 Thermal stability among these properties is an important para-meter for conductive polymers.
Thermal behavior and stability are a significant role for the future utilization as conducting polymers (CPs). One of the most considerable and reliable factors of CPs is the measurement or evaluation of their thermal stability. Thermal properties and interaction of monomer and polymer can be estimated from the oxidative degradation curves through TGA studies.27
In this study, a star-shaped electroactive triazine monomer is synthesized and its spectroelectrochemical and electrochemical properties are examined. Electrochemical polymerization of TCZ was achieved in acetonitrile using lithium perchlorate (LiCIO4) as the supporting electrolyte. Fluorescence studies indicated that the monomer is a purple color, while the polymer is a blue color. Additionally, thermal analysis demonstrated that polymer revealed excellent stability even at 1000 1C. In the second part of the study, we constructed dual-type electrochromic devices based on poly-(2,4,6-tris(2-(9H-carbazol-9-yl)ethoxy)-1,3,5-triazine) (PTCZ) and poly(3,4-ethylenedioxythiophene) (PEDOT). The neutral state of the device shows a transparent color, while the oxidized state reveals a blue color that is the most important color characteristic for smart windows.
Experimental
Chemicals and equipment
Acetonitrile (Aldrich), dichloromethane (DCM) (Merck), dimethyl sulfoxide (DMSO) (ACS reagent, Z99, Merck) 2-(9H-carbazol-9-yl)ethanol (Alfa Aesar), lithium perchlorate (LiCIO4) (Aldrich), NaOH (Tekkim), propylene carbonate (PC) (Sigma-Aldrich), poly(methylmethacrylate) (PMMA) (Sigma-Aldrich) and 2,4,6-trichloro-1,3,5-triazine (Cyanuric chloride) (Z99, Merck) were used as received from their indicated commercial suppliers without any further purification.
Electropolymerization and electrochemical measurements were carried out with an Ivium potentiostat/galvanostat. An Agilent 8453 UV-vis spectrophotometer was used to perform the
Chemistry Department, Faculty of Art and Science, Pamukkale University, Denizli 20070, Turkey. E-mail: metinak@pau.edu.tr
Received 19th April 2016, Accepted 5th July 2016 DOI: 10.1039/c6cp02611g www.rsc.org/pccp
PCCP
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