ORIGINAL PAPER Synthesis and structural and thermal properties of cyclotriphosphazene-based ionic liquids: tribological behavior and OFET application Ali Destegül 1 & Hüseyin Akbaş 1 & Ahmet Karadağ 1,2 & Betül Canımkurbey 3 & Yusuf Yerli 4 & Kadir Cihan Tekin 5 & Uğur Malayoğlu 6 & Zeynel Kılıç 6 Received: 28 November 2018 /Revised: 28 December 2018 /Accepted: 29 December 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract Three new fully substituted starting materials (Pz1-3) were synthesized reacting dimethylaminoethanol, 3-dimethylamino-1- propanol, and 4-pyrridinemethanol, which were saltified using metallic sodium, with partly substituted phosphazene (Pz) com- pound. Phosphazene-based ionic liquids (PzILs), PzIL1-3, were obtained from the reaction of the starting materials with CH 3 I. New ionic liquids (PzIL1a-3a) were obtained by replacing the I - ions of these ionic liquids with the NTf 2 - anions. The structures of PzILs were elucidated by elemental analysis, FTIR, and 1 H, 13 C{ 1 H}, and 31 P{ 1 H} NMR techniques. The thermal properties of all compounds were investigated using thermogravimetric (TG) analysis. Compared with the output materials, the thermal stability of the ionic liquids was found to be higher, 160, 199, and 228 °C for PzIL1-3 respectively, and 270, 204, and 287 °C for PzIL1a-3a respectively. At the same time, the viscosity measurements of PzIL1a-3a compounds obtained as liquids in room temperature were measured with a cone/plate viscometer. It is understood from the viscosity values that the fluidities of these compounds are as low as 864, 3801, and 423,700 cP, respectively (water viscosity is 0.7977 cP at 30 °C). In addition to these studies, sliding wear test was conducted at room temperature using AA7075 disc specimen against the stationary 100Cr6 steel ball. The wear protection of PzILs was determined considering the volume loss of AA7075. Keywords Phosphazene . Phosphazene-based ionic liquid . Tribology . Organic field-effect transistor Introduction Phosphazenes are compounds containing a phosphorus- nitrogen double bond in their skeleton. Phosphazenes are mainly classified into three categories as the cyclo-, poly-, and open-chain phosphazenes. Cyclo and poly phosphazenes are more stable than open-chain phosphazenes and therefore are the best known and the most intensively studied phosphazene compounds [1]. There are numerous applica- tions related to heterocyclic cyclophosphazenes such as bio- medical materials [2], flame retardants [3], liquid crystals [4, 5], lubricants [6, 7], electrical conductors [8], Li-ion batteries [9], OLEDs [10, 11], and coordination chemistry [12, 13]. In addition, cyclophosphazenes are considered as new drug can- didates for the treatment of various diseases, particularly can- cer, microbial, and fungal [14–19]. This versatile usage dem- onstrates the importance of the phosphazene derivatives. By making the substituents of the phosphazene ring ionizable, a Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11581-019-02846-4) contains supplementary material, which is available to authorized users. * Ahmet Karadağ akaradag@bartin.edu.tr 1 Department of Chemistry, Gaziosmanpaşa University, 60250 Tokat, Turkey 2 Department of Biotechnology, Bartın University, 74100 Bartın, Turkey 3 Department of Physics, Amasya University, 05100 Amasya, Turkey 4 Department of Physics, Yıldız Technical University, 34349 Istanbul, Turkey 5 Department of Metallurgical and Materials Engineering, Dokuz Eylül University, 35390 İzmir, Turkey 6 Department of Chemistry, Ankara University, 06100 Ankara, Turkey Ionics https://doi.org/10.1007/s11581-019-02846-4