Redox-Active Polymeric Ionic Liquids with Pendant N-Substituted Phenothiazine

Abstract

Polymers that are elastic while supporting charge transport are desirable for flexible and soft electronics. Many polymers with bulky and conjugated redox-active pendant units have high glass transition temperatures (T g) in their neutral form that will not lead to elasticity at room temperature. Their behavior in charged form in the solid state without an electrolyte has not been extensively studied. Here, the design strategy of polymeric ionic liquid where two weakly interacting ionic groups are used to maintain a low T g is shown to lead to flexible redox active polymers. The use of a flexible ethylene backbone and redox-active phenothiazine (PTZ)-based pendant group resulted in polymers with relatively low T g that are electrically conductive. PTZ that was N-substituted with 2-(2-ethoxyethoxy)­ethoxy)­ethyl was found to promote solubility of the polymer and lower the T g of the neutral polymer by ∼150 °C relative to that of the T g of a variant without the N-substituent. Doping with trifluoromethanesulfonimide leads to an electrically conductive polymer without significantly increasing the T g. Physical characterization by UV–vis–NIR spectroscopy, electron spin resonance spectroscopy, and impedance spectroscopy verified that the molecular design leads to an efficient charge hopping between the PTZ groups.

Interfacial doping of semiconducting polymers with phenothiazine-based polymeric ionic liquids

“…To increase the versatility of synthesis here we examine phenothiazine (PTZ), which forms stable radical cations when oxidized and has appropriate energetics to control electron transfer with organic semiconductors. 29 PTZ has been widely introduced in batteries as a redox-active molecules and was demonstrated to generate robust and stable radical cations. [30][31][32] In our previous work, we have synthesized polymers with sidechain-attached PTZ units that are Nsubstituted with 2-((2-ethoxyethoxy)ethoxy)ethyl (EE) groups referred to as (pPTZ-EE).…”

“…[30][31][32] In our previous work, we have synthesized polymers with sidechain-attached PTZ units that are Nsubstituted with 2-((2-ethoxyethoxy)ethoxy)ethyl (EE) groups referred to as (pPTZ-EE). 29 The EE groups served to lower the glass transition temperature, T g , of (pPTZ-EE) and to improve the solubility of the polymer. We demonstrated the use of PTZ radical cation pendants as redox-active low-T g and chargeconducting polymeric ionic liquids (PILs), i.e.…”

“…charged polymers incorporating units akin to common ionic liquids. 29 The radical cations present in the PTZ-containing polymer chain could be adjusted by a controlled oxidation reaction with the amount of TFSI À counter anions, which resulted in tunable electrical conductivity with radical/TFSI À loading. Herein, we describe the use of redox-active PTZ-containing polymers to boost the electrical conductivity of poly(3-hexylthiophene) (P3HT).…”

Molecular Dynamics Simulations of Rhodamine B Zwitterion Diffusion in Polyelectrolyte Solutions

“…Given their widespread prevalence in the natural world and their unique properties, it is little wonder that the study of PEs continues unabated in the physical and life sciences. Although a great deal of recent research attention has focused on PE multilayer thin films − and complexes, − which involve two oppositely charged PEs, and on the use of polymeric ionic liquids for use in batteries and other applications, − PE solutions continue to attract attention as well.…”

Liquid Co-crystals of Dual-Active Phenothiazine–NSAID Drugs: Synthesis, Spectroscopic, and Thermal Characterization

“…Second, in 2010, Dumitriu et al 21 synthesized new liquid-state imidazolium-functionalized phenothiazine derivatives. Finally, Oh et al 22 used N-substituted phenothiazines as pendant groups in polymeric ionic liquids. However, there is no report on investigating the synthesis of liquid-state dual-functional phenothiazine drugs.…”