rs, oligoesters or an ACA triblock, wherein in said ACA triblock, A is a polyester unit and C is selected from the group consisting of poly(ethylene oxide), poly(ethylene oxide)-co-poly(propylene oxide), a poly(ethylene oxide) rich chain, a diol and a diamine as set forth above, said diamine being preferably selected from the group consisting of C2 to C24 (preferably, C2 to C12) diamines, more pre