The invention relates to invention relates to a statistical copolymer represented by the following formula (I): Ini-[Ox]m-[Oz]n-Nuc (I) wherein: Ini represents a residue of an initiator of cationic polymerization, Nuc represents a residue of a nucleophilic agent, Ox represents N(R1)CHRaCHRa; each R1 independently represents H or C(O)R11; and R11 independently represents optionally substituted C1-12 alkyl, optionally substituted cycloalkyl, optionally substituted aralkyl or optionally substituted aryl; Oz represents N(R2)CHRaCHRaCHRa; each R2 independently represents C(O)R21 or H; and R21 independently represents optionally substituted C1-12 alkyl, optionally substituted cycloalkyl, optionally substituted aralkyl or optionally substituted aryl; each Ra independently represents H, linear or branched C1-3 alkyl; m≥5; n≥5; m+n≥20; 3:97≤m:n≤97:3. The statistical copolymers of the present invention exhibit useful properties that can be exploited in the medical field, especially in polymer micelles for drug delivery and polyplexes for DNA delivery.