Patent ID: 8900792

Claim:
A copolymer comprising: a first polymerized unit formed from a compound having the formula or a combination comprising at least one of the foregoing, where each R 1 is independently H, F, C 1-6 alkyl, or C 1-6 fluoroalkyl, and G + has formula (VI): wherein R 6 , R 7 , and R 8 are each independently hydroxy, nitrile, halogen, C 1-10 alkyl, C 1-10 fluoroalkyl, C 1-10 alkoxy, C 1-10 fluoroalkoxy, C 6-20 aryl, C 6-20 fluoroaryl, C 6-20 aryloxy, or C 6-20 fluoroaryloxy, r is an integer from 0 to 5, and s and t are each independently an integer from 0 to 4; a second polymerized unit comprising an acid sensitive functional group; and a third polymerized unit comprising a polar group, wherein the third polymerized unit is formed from a polar monomer chosen from or a combination comprising at least one of the foregoing, wherein R 10 is H, F, C 1-6 alkyl, or C 1-6 fluoroalkyl.