High performance hybrid fluoropolymer composites membranes

A grafted fluoropolymer [polymer (F-j)], obtained by a process comprising the following steps:

• (i) providing a composition [composition (C1)] containing a liquid medium [medium (L)] and at least one fluoropolymer [polymer (F)], wherein said polymer (F) comprises:
• recurring units derived from at least one fluorinated monomer [monomer (FM)], and
• recurring units derived from at least one monomer [monomer (FPM)], said monomer (FPM) comprising at least one functional group [group (FX)] selected from the group consisting of:
• hydroxyl group, amine, carboxylic, thiol and anhydride;
• (ii) contacting composition (C1) with at least a first metal compound [compound (M1)] of formula (I):
• X4-mAYm (I)
• wherein m is an integer from 1 to 3, A is a metal selected from the group consisting of Si, Ti and Zr, each occurrence of Y is a hydrolysable group and each occurrence of X is a hydrocarbon group, wherein at least one X comprises at least one epoxy functional group,
• so that at least a fraction of the group (FX) of monomer (FPM) of polymer (F) is reacted with at least a fraction of compound (M1), thereby providing a composition [composition (C2)] comprising at least one grafted fluoropolymer [polymer (F-j)] bearing -AYm pendant groups;
• and
• (iib) isolating the fluoropolymer [polymer (F-j)] as solid by filtration of composition (C2), washing the solid with polar solvents and drying to recover dry polymer (F-j).

A process for manufacturing a polymer electrolyte membrane, said process comprising:

• (i) providing a composition [composition (C5)] containing a liquid medium [medium (L)] and at least one fluoropolymer [polymer (F)], wherein said polymer (F) comprises:
• recurring units derived from at least one fluorinated monomer [monomer (FM)], and
• recurring units derived from at least one monomer [monomer (FPM)], said monomer (FPM) comprising at least one functional group [group (FX)] selected from the group consisting of:
• hydroxyl group, amine, carboxylic, thiol and anhydride,
• wherein the liquid medium (L) also comprises at least one metal salt(S);
• and
• (ii) contacting composition (C5) with at least a first metal compound [compound (M1)] of formula (I):
• X4-mAYm (I)
• wherein m is an integer from 1 to 3, A is a metal selected from the group consisting of Si, Ti and Zr, each occurrence of Y is a hydrolysable group and each occurrence of X is a hydrocarbon group, wherein at least one X comprises at least one epoxy functional group,
• so that at least a fraction of the group (FX) of monomer (FPM) of polymer (F) is reacted with at least a fraction of compound (M1), thereby providing a composition [composition (C2′)] comprising at least one grafted fluoropolymer [polymer (F-j)] bearing -AYm pendant groups;
• and
• (iii) contacting composition (C2′) with at least a second metal compound [compound (M2)], different from the compound (M1), of formula (II):
• X′4-m′A′Y′m′ (II)
• wherein m′ is an integer from 1 to 4, A′ is a metal selected from the group consisting of Si, Ti and Zr, each occurrence of Y′ is a hydrolysable group and each occurrence of X′ is a hydrocarbon group, optionally comprising at least one functional group [group (FX′)], different from group (FX), so that at least a fraction of compound (M2) is reacted with at least a fraction of the -AYm pendant groups of polymer (F-j),) thereby providing a composition [composition (C3′)] comprising at least one grafted fluoropolymer [polymer (F-g)] bearing -A′Y′m pendant groups;
• (iv) hydrolysing and/or condensing the -A′Y′m pendant groups of polymer (F-g) thereby providing a composition [composition (C4′)] comprising at least one fluoropolymer hybrid organic/inorganic composite [polymer (F-h)];
• (v) processing composition (C4′) into a film;
• and
• (vi) drying the film provided in step (v).