A biodegradable aliphatic polyester which is a reaction product of a functional Michael acceptor and a functional Michael donor, wherein the functional Michael acceptor comprises R1(A)n and the functional Michael donor comprises R2(D)m, wherein A is a functional Michael acceptor moiety, D is a functional Michael donor moiety, n is an integer which is at least one, m is an integer which is at least one, R1 and R2 are biodegradable structures.