"???a??? is a positive number of 1 to 3, R is a single bond, methylene group, oxygen atom, NH group or sulfur atom, R2 and R3 each are a single bond or methylene group, R5 is a fluorinated alkyl group which optionally contains an ether or ester bond, R6 and R11 are, each independently, hydrogen or a straight alkyl group of 1 to 11 carbon atoms, R7 is hydrogen, a straight alkyl group of 1 to 10 carb" . . . . . . . . . . .