A polymer comprises the polymerized product of monomers comprising an acid-deprotectable monomer, a base-soluble monomer, a lactone-containing monomer, and a photoacid-generating monomer; a chain transfer agent of the formula; wherein Z is a y valent C1-20 organic group, x is 0 or 1, Rd is a substituted or unsubstituted C1-20 alkyl, C3-20 cycloalkyl, C6-20 aryl, or C7-20 aralkyl; and optionally, an initiator.