Copolymer PAX.Y/PE comprising polyamide PA blocks alternating with polyether PE blocks, the PA blocks being composed of homopolyamide PAX.Y blocks obtained by polycondensation: - of a linear aliphatic diamine having X carbon atoms; - of a dicarboxylic acid having Y carbon atoms chosen from linear aliphatic diacids; said copolymer being characterized in that: - said PA blocks comprise carboxyl ends; - X is at least equal to 4, preferably at least equal to 6; - Y is at least equal to 10, preferably at least equal to 12; - said PE blocks: (i) preferably, are either PE blocks comprising hydroxyl ends, otherwise known as PE diol blocks, so that the bonds between the PA blocks comprising carboxyl ends and the PE diol blocks are ester bonds; (ii) preferably, or are PE blocks comprising NH 2 ends in the case where Y has a number of carbon atoms of greater than 14, so that the bonds between the PA blocks comprising carboxyl ends and the PE blocks comprising NH 2 ends are amide bonds; (iii) comprise from 0 to 39% by weight of PO3G and/or PEG and from 100 to 61% by weight of polyether other than PO3G or PEG (% by weight, expressed with respect to the total weight of the copolymer); characterized in that (iv) the crystallinity of the PAX.Y block is > the crystallinity of a PA12 block of the same size and/or (v) the PA/PE phase separation of said copolymer PAX.Y/PE is > that of a copolymer PA12/PTMG composed of PA12 blocks of the same size as the PAX.Y blocks of said copolymer PAX.Y/PE and of PTMG blocks of the same size as the PE blocks of the PAX.Y/PE copolymer, characterized in that X + Y = 24 with PA blocks made of PA10.14 or made of PA6.18, or in that X + Y = 22 with PA blocks made of PA10.12, or in that X + Y = 20 with PA blocks made of PA6.14 or made of PA10.10. - of a linear aliphatic diamine having X carbon atoms; - of a dicarboxylic acid having Y carbon atoms chosen from linear aliphatic diacids; - said PA blocks comprise carboxyl ends; - X is at least equal to 4, preferably at least equal to 6; - Y is at least equal to 10, preferably at least equal to 12; - said PE blocks: (i) preferably, are either PE blocks comprising hydroxyl ends, otherwise known as PE diol blocks, so that the bonds between the PA blocks comprising carboxyl ends and the PE diol blocks are ester bonds; (ii) preferably, or are PE blocks comprising NH 2 ends in the case where Y has a number of carbon atoms of greater than 14, so that the bonds between the PA blocks comprising carboxyl ends and the PE blocks comprising NH 2 ends are amide bonds; (iii) comprise from 0 to 39% by weight of PO3G and/or PEG and from 100 to 61% by weight of polyether other than PO3G or PEG (% by weight, expressed with respect to the total weight of the copolymer); characterized in that (iv) the crystallinity of the PAX.Y block is > the crystallinity of a PA12 block of the same size and/or (v) the PA/PE phase separation of said copolymer PAX.Y/PE is > that of a copolymer PA12/PTMG composed of PA12 blocks of the same size as the PAX.Y blocks of said copolymer PAX.Y/PE and of PTMG blocks of the same size as the PE blocks of the PAX.Y/PE copolymer, characterized in that X + Y = 24 with PA blocks made of PA10.14 or made of PA6.18, or in that X + Y = 22 with PA blocks made of PA10.12, or in that X + Y = 20 with PA blocks made of PA6.14 or made of PA10.10. (i) preferably, are either PE blocks comprising hydroxyl ends, otherwise known as PE diol blocks, so that the bonds between the PA blocks comprising carboxyl ends and the PE diol blocks are ester bonds; (ii) preferably, or are PE blocks comprising NH 2 ends in the case where Y has a number of carbon atoms of greater than 14, so that the bonds between the PA blocks comprising carboxyl ends and the PE blocks comprising NH 2 ends are amide bonds; (iii) comprise from 0 to 39% by weight of PO3G and/or PEG and from 100 to 61% by weight of polyether other than PO3G or PEG (% by weight, expressed with respect to the total weight of the copolymer);