Chain-terminated N-vinyl lactam polymers and graft-copolymers and methods for making same

A water-soluble polyvinyl 5-membered lactam having a molecular weight ranging from about 1000 to about 20,000 and chain-terminated with a compound selected from the group consisting of compounds of the following formulas ##STR1## wherein R and R.sup.1 are C.sub.1 to C.sub.4 alkyl or substituted alkyl; n is 0 to 20; R.sup.II is ethylene; R.sup.III is C.sub.1 to C.sub.24 alkylene or substituted alkylene; and R.sup.IV is C.sub.1 to C.sub.4 alkyl or substituted alkyl; can be prepared by polymerizing an N-vinyl 5-membered lactam in a liquid solvent-chain terminator compound of the formula (I) or (II) in the presence of a free radical initiator. The lactam polymer so-obtained may be activated and grafted to (conjugated with) a drug or an enzyme to alter the properties thereof.