Abstract
The synthesis and characterisation of novel poly[VDF‐g‐oligo(EO)] graft copolymers (where VDF and EO stand for vinylidene fluorideand ethylene oxide, respectively) are presented. First, 2‐trifluoromethyl oligo(EO) acrylate, MAFTEG, was prepared by esterification oftriethylene glycol monomethyl ether (TEG) with 2‐trifluoromethacrylic acid (MAF) catalyzed by methanesulfonic acid, in 50% yields. Then, various radical copolymerisations of such MAFTEG with VDF from different feeds (VDF ranging from 85 to 95 mol.%) led torandom poly[VDF‐co‐MAFTEG] copolymers that bore oligo(OE) side‐chains in satisfactory yields (60‐70%). These original graftcopolymers were characterised by 1H and 19F NMR spectroscopy. Their molar masses reached ca. 7,000 g∙mol‐1 and their thermalproperties were investigated while their glass transition temperatures ranged between ‐31 and ‐19 °C. Their thermogravimetricanalyses under air showed decomposition temperatures from 235 to 325 °C with 10 % weight loss (Td,10%). Gel polymer electrolytes were achieved at room temperature by blending ionic liquid electrolyte (RTIL), poly[VDF‐g‐oligo(EO)] graft copolymers, and silicananoparticles, the ionic liquid being made of 1‐propyl‐1‐methyl pyrrolidinium bis(fluorosulfonyl)imide (PyrFSI) dissolving lithiumbis(trifluoromethanesulfonyl)imide (LiTFSI). These novel copolymers are of potential interest as gel polymer electrolytes in lithium ionbatteries, showing competitive ambient conductivities of 0.2 mS.cm‐1 that increased up to 0.5 mS.cm‐1 with a content of silicananoparticles at 20 wt%. In addition, the electrolyte gel appeared to be electrochemically stable in a wide range of potentials varyingfrom 1.5 V to 4.1 V vs. Li+/Li, compatible with 4 V class lithium ion batteries.