A polymer includes repetitive units derived from a monomer compound according to formula (I): ##STR00001## wherein R.sup.1 is a hydrogen atom, a methyl group or an ethyl group, A, which is identical or different, is a group comprising an ester group of formula -A.sup.1-C(O)--O-A.sup.2-, or an amide group of formula -A.sup.1-C(O)--NR.sup.10-A.sup.2-, wherein: R.sup.10, which is identical or different, is hydrogen or an alkyl, hydroxyalkyl, or aminoalkyl C.sub.1-C.sub.6 linear or branched group, A.sup.1, which is identical or different is a covalent bond or a group of formula --(CH.sub.2).sub.p1-- wherein p1 is an integer of from 1 to 6, A.sup.2, which is identical or different, is a linear or branched hydrocarbon group comprising optionally N, O, or S heteroatoms or heterogroups, optionally substituted, optionally forming or comprising a cycle, R.sup.1, R.sup.2, R.sup.3, R.sup.5 and R.sup.6, which are identical or different, are hydrogen, alkyl, hydroxyalkyl, or aminoalkyl C.sub.1-C.sub.6 linear or branched groups, or, if inside the brackets, form a heterocycle with group A.sup.2, m is an integer of from 1 to 10, n is an integer of from 1 to 6, Z is --O--, --C(O)O--, or --C(O)NH--, B is a linear or branched C.sub.2-C.sub.12 polymethylene chain, optionally comprising heteroatoms or heterogroups, and optionally substituted with one or several hydroxy or amino groups, and X.sup.-, which are identical or different, are counter ions.