The invention relates to a copolymer comprising at least two distinct polyamide blocks and at least one polyether block, and a method for preparation of said copolymer comprising the following steps: —in a first step, the polyamide block PA1 is prepared by polycondensation of chosen monomers: amino acids, lactames or diamines and dicarboxylic acids, in the presence of an appropriate chain limiter; —then, in a second optional step, the polyamide PA1 block obtained is reacted with all or part of the polyether PE blocks, in the presence or absence of a catalyst; —in a third step, the polyamide PA2 block is prepared by polycondensation of the chosen isomers: amino acids, lactams or diamines and dicarboxylic acids, in the presence of an appropriate chain limiter; —in a fourth optional step, the polyamide PA2 block obtained is reacted with all or part of the polyether PE blocks, in the presence or absence of a catalyst; —in a fifth step, PA1 or the reaction medium from step 2 is reacted with PA2 or the reaction medium from step 4 and with PE or the remainder of PE not added in step 2 or 4.