Abstract: A process for preparing a nylon block polymer which comprises bringing into reactive contact lactam monomer, basic lactam polymerization catalyst and a composition containing one or more acyllactam functional materials selected from the group consisting of: ##STR1## wherein, Q is ##STR2## with Y=C.sub.3 -C.sub.11 alkylene; a is an integer equal to 1, 2 or 3;b is an integer equal to 2 or more;R is a di- or a poly- valent group selected from hydrocarbon groups and hydrocarbon groups containing ether linkages;Z is a segment of: (1) a polyether or polymeric hydrocarbon; (2) a polyester containing polyether segments (3) a hydrocarbon; (4) a polysiloxane; or (5) combinations thereof.