Fluoropolyether-based elastomers having low glass transition temperature

A curable precursor composition for a fluoroelastomer comprising

• a) at least one functionalized fluoropolyether containing moieties selected from (—C4F8O—), (—C3F6O—), (—C2F4O—), (—CF2O—) or combinations thereof, wherein the fluoropolyether is functionalised to contain at a terminal position or at a position that is adjacent to the terminal position at least one first functional group, and
• b) one or more coagents comprising at least two second functional groups,
• wherein the first and second functional groups are capable of reacting with each other in a curing reaction to form a fluoroelastomer, and wherein the first functional group is selected from the group consisting of an alkyne unit and a nitrile unit;
• and the second functional group is an azide unit,
• further wherein the composition comprises at least 40% by weight based on the total weight of the composition of the functionalized fluoropolyether.