A polymer comprising: - i) at least one repetitive unit having the following formula: and - ii) at least one, preferably at least two, repetitive unit(s) having the following formula: or at least one, preferably at least two, repetitive unit(s) having the following formula: or at least one, preferably at least two, repetitive unit(s) having the following formula (S'): wherein: - A 1 represents H or a linear or branched divalent alkyl group comprising from 1 to 20 carbon atoms, preferably from 2 to 12, and more preferably from 5 to 10; - A 4 represents a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 2 to 12, and more preferably from 4 to 10; - A 2 represents a bond or a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 1 to 10, and more preferably from 1 to 5; - A 3 represents a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 1 to 10, and more preferably from 1 to 5; - R 1, R' 1, R 2 and R 3 are or H; - i is 0, 1 or 2; - j is 0 or 1; i being 0 when j is 1 and j being 0 when i is 1 or 2; when A 1 is H and i is 0, then A 2 is a bond, and wherein: in the unit having the formula, only one of R 1, R 2 and R 3 is H; in the unit having the formula (S'), one or two of R 1, R' 1, R 2 and R 3 is H. - i) at least one repetitive unit having the following formula: and - ii) at least one, preferably at least two, repetitive unit(s) having the following formula: or at least one, preferably at least two, repetitive unit(s) having the following formula: or at least one, preferably at least two, repetitive unit(s) having the following formula (S'): wherein: - A 1 represents H or a linear or branched divalent alkyl group comprising from 1 to 20 carbon atoms, preferably from 2 to 12, and more preferably from 5 to 10; - A 4 represents a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 2 to 12, and more preferably from 4 to 10; - A 2 represents a bond or a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 1 to 10, and more preferably from 1 to 5; - A 3 represents a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 1 to 10, and more preferably from 1 to 5; - R 1, R' 1, R 2 and R 3 are or H; - i is 0, 1 or 2; - j is 0 or 1; - A 1 represents H or a linear or branched divalent alkyl group comprising from 1 to 20 carbon atoms, preferably from 2 to 12, and more preferably from 5 to 10; - A 4 represents a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 2 to 12, and more preferably from 4 to 10; - A 2 represents a bond or a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 1 to 10, and more preferably from 1 to 5; - A 3 represents a linear or branched divalent alkylene radical comprising from 1 to 20 carbon atoms, preferably from 1 to 10, and more preferably from 1 to 5; - R 1, R' 1, R 2 and R 3 are or H; - i is 0, 1 or 2; - j is 0 or 1; in the unit having the formula, only one of R 1, R 2 and R 3 is H; in the unit having the formula (S'), one or two of R 1, R' 1, R 2 and R 3 is H.