Synthesis and properties of aromatic polyethers containing poly(ethylene oxide) side chains as polymer electrolytes for lithium ion batteries Andrea V € oge a, * , Valadoula Deimede a, ** , Fotis Paloukis b , Stylianos G. Neophytides b , Joannis K. Kallitsis a a Department of Chemistry, University of Patras, 26500 Patras, Greece b Foundation of Research and Technology e Hellas, Institute of Chemical Engineering Sciences (FORTH/ICE-HT), Patras 26504, Greece highlights graphical abstract  Polymer electrolytes bearing PEO side chains of varying lengths were designed.  DMA and TGA show that T g and T d can be controlled by varying the PEO content.  XRD confirms polymers amorphous character, independent of the PEO content.  Membranes doped in liquid electro- lyte have high conductivities (10 3 S cm 1 , 80  C). article info Article history: Received 6 December 2013 Received in revised form 20 June 2014 Accepted 9 July 2014 Available online 30 July 2014 Keywords: Polymers Thin films Nuclear magnetic resonance (NMR) Thermogravimetric analysis (TGA) Glass transitions abstract Polymer electrolytes consisting of polar pyridine units in the backbone and poly(ethylene oxide) (PEO) side chains are designed for possible application in lithium ion batteries. In particular, aromatic poly- ethers bearing PEO side chains with varying length are synthesized either by copolymerization of the corresponding PEO based diols with different arylfluorides or by modification of dihydroxyl function- alized precursor polymers with poly(ethylene oxide) methyl ether tosylate. The formation of free standing films is dependent on the PEO content, polymers' composition as well as on the different monomers used. The mechanical properties study shows that the glass transition temperature can be controlled by varying the PEO content. Thermal stability is also influenced by the PEO length: the shorter the PEO side chain, the higher the stability. XRD analysis gives information about the desired amorphous character of these polymers, which is independent of the PEO content. Solid polymer electrolytes pre- pared by blending the PEO-based polymers with lithium salt and PEO 2000 (used as plasticizer) show ambient temperature conductivities in the range of 10 6 S/cm. To further improve conductivity doping of PEO-based polymers in liquid electrolyte (1 M LiPF 6 in EC/DMC 1/1) in some cases results in high con- ductivities in the range of 10 3 S cm 1 at 80  C. © 2014 Elsevier B.V. All rights reserved. 1. Introduction In recent years, lithium ion batteries have attracted significant interest for a variety of applications, such as portable electronics and electric vehicles (EV) due to their high energy densities [1e3]. * Corresponding author. Tel.: þ30 2610 997121; fax: þ30 2610 997122. ** Corresponding author. Tel.: þ30 2610 962958; fax: þ30 2610 997122. E-mail addresses: andreavoege@online.de (A. V€ oge), deimede@upatras.gr (V. Deimede). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys http://dx.doi.org/10.1016/j.matchemphys.2014.07.012 0254-0584/© 2014 Elsevier B.V. All rights reserved. Materials Chemistry and Physics 148 (2014) 57e66