A Systematic Study of Vinyl Ether-Based Poly(Ethylene Oxide) Side-Chain Polymer Electrolytes

Herein, we report on the synthesis of a systematic library of vinyl ether-based poly(ethylene oxide) (PEO) side-chain copolymers in order to reduce the crystallization of PEO. The influence of different grafted PEO side chain lengths, the grafting density, and the [Li+]:[EO] ratio after mixing with LiTFSI on the glass transition temperature (Tg), the crystallinity, and the resulting ionic conductivity was examined. Copolymers bearing longer PEO side chains and higher grafting densities show higher crystallization tendencies while their Tg is reduced at the same time. Furthermore, the addition of LiTFSI reduces crystallization but increases Tg. Because these effects are directly impacting the ionic conductivity, we demonstrate that the different parameters need to be carefully adjusted in order to balance their influence. In this way, a fundamental view that shows the potential of PEO side-chain copolymers for their applications as polymer electrolytes is provided.