The invention relates to a process for preparing a branched polymer by contacting a monofunctional or difunctional polymer whose functional group is at least an -OH or an -NH2 group with a multifunctional compound RYn, where n > 2 and Y is an -OH group, an -NHm group where m=1,2 or a -COOH group and R is an alkyl, an aryl group or a cyclic group and in which the Y groups need not be the same and in which carbonyl bislactamate is also present.
