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 (T-g), 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 T-g is reduced at the same time. Furthermore, the addition of LiTFSI reduces crystallization but increases T-g. 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.