The present invention relates to an aqueous polymer dispersion, which includes hard/soft Shell structured particles, with the polymer phase of the core P1 having a glass transition temperature Tg1 from 60 to 120° C., the polymer phase of the shell P2 having a glass transition temperature Tg2 from −20 to 40° C., the minimum film-formation temperature MFFT being from 0 to 50° C., with the phase P1 representing from 1.5 to 60% by weight, with respect to the total weight of P1+P2, the phase P1 including at least one monomer M1 having at least two copolymerizable ethylenic unsaturations and at least one ethylenically unsaturated monomer M2 having at least one carboxylic acid and/or anhydride functional group, the phase P2 being from 40 to 85% by weight of the total weight of P1+P2 and with said phase P2 including: at least one monomer M3 selected from the monomers having, in addition to the polymerizable ethylenic unsaturation, at least one group selected from acetoacetoxy, diacetone, methylol or alkoxysilane. The invention also relates to protective and/or decorative coating compositions such as paints, varnishes, transparent coatings, inks or adhesives and fiber treatment compositions.”