TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The comonomer (MA) is (meth)acrylic monomers of formula ((R2a)(R1a)C=C(R3a)(C=O-O-R1b)) (III) or vinyl ether monomers of formula ((R2a)(R1a)C=C(R3a)(O-R1b)) (IV).R1a-R3a = H (preferred) or 1-3C hydrocarbyl; andR1b = 1-5C hydrocarbyl moiety comprising at least one OH (preferred) or H.The polymer (F1) comprises: polymers (F-1) comprising recurring units derived from at least one MA, at least one per(halo)fluoromonomer comprising tetrafluoroethylene or chlorotrifluoroethylene, and at least one hydrogenated monomer comprising ethylene, propylene or isobutylene, optionally containing 0.1-30 mole% at least one additional comonomers; or polymers (F-2) comprising recurring units derived from at least one MA, vinylidene fluoride (VDF) and optionally from at least one fluorinated monomers different from VDF. (M1) is of formula (R1m4-mE1(R1m)m).m = 1-4 or 1-3;E1 = Si, Ti or Zr; andR1m = 1-18C hydrocarbyl optionally comprising at least one functional group.The liquid medium comprises: at least one diester of formula (R1c-OOC-Z3-COOR2c) (de1) and at least one diester of formula (R1c-OOC-Z4-COOR2c) (de2), possibly in combination with at least one diester of formula (R1c-OOC-(CH2)4-COOR2c) (de3) and/or at least one ester-amide (R1c-OOC-Z3-COONR3cR4c) (ea1) and at least one ester-amide of formula (R1c-OOC-Z4-COONR3cR4c) (ea2), possibly in combination with at least one (IIea).Z3 = MG1a-CH(CH3)-CH2-CH2- or MG1b-CH2-CH2-CH(CH3)-;Z4 = - ES1a-CH(C2H5)-CH2- or ES1b-CH2-CH(C2H5)-;R1c, R2c = 1-20C alkyl, 1-20C aryl, 1-20C alkylaryl, or 1-20C arylalkyl; eitherR3c, R4c = 1-20C alkyl, 1-20C aryl, 1-20C alkylaryl, or 1-20C arylalkyl (all comprising at least one substituents, optionally having at least one heteroatom); orNR3cR4c = cyclic moieties optionally comprising at least one O or additional N; andMG1a, MG1b, ES1a, ES1b = not defined.The liquid medium comprises: a diester mixture consisting essentially of 70-95 wt.% (de1), 5-30 wt.% (de2) and 0-10 wt.% (de3); and/or an ester-amide mixture consisting essentially of 70-95 wt.% (ea1), 5-30 wt.% (ea2) and 0-10 wt.% (IIea). The liquid medium further comprises dimethylsulfoxide and optionally at least more organic solvent different from dimethylsulfoxide. The fluoropolymer comprises 1-30 wt.%, preferably 5-20 wt.% (F1). The fluoropolymer film is a polymer electrolyte separator comprising at least one electrolytic salt. EXAMPLE - 2455 g Demineralized water and 0.63 g METHOCEL K100 CR (RTM: Hydroxypropyl methylcellulose) were added to reactor. The reactor was vented and pressurized with nitrogen to 1 bar, then 8.55 g tert-amyl perpivalate in isododecane was introduced, followed by 107 g hexafluoropropylene and 947 g vinylidene fluoride monomer. The reactor was heated to 52 degrees C to a final pressure of 110 bar. Temperature was maintained constant at 55 degrees C throughout the whole trial. Pressure was maintained constant at 110 bar throughout the whole trial by feeding a 19.96 g/l aqueous solution of 2-hydroxyethyl acrylate monomer to a total of 709 ml. After 510 minutes the polymerization run was stopped by degassing the suspension until reaching atmospheric pressure. The obtained polymer was recovered, washed with demineralized water and oven-dried at 50 degrees C. 1.24 g polymer was dissolved in 23.79 g RHODIASOLV IRIS (RTM: Dimethyl 2-methylglutarate) diester mixture. 3.9 g Tetraethyl orthosilicate was added to stirred solution, followed by 4 ml aqueous formic acid. The mixture was stirred at 80 degrees C for 2 hours to obtain a clear solution of a hybrid vinylidene fluoride/hexafluoropropylene/2-hydroxyethyl acrylate-silica composite.