Polymer compositions, typically thermoplastic polymer compositions, readily converted into electroconductive polymers and articles shaped therefrom, e.g., films, comprise at least one convertible polymer support substrate (A) and at least one amphiphilic heterocyclic monomer (B) having the formula (I): ##STR1## in which R.sub.1 and R.sub.2, which may be identical or different, are each a linear or branched alkyl, aryl, alkylaryl, arylalkyl, hydroxycarbonyl, alkoxycarbonyl or amide radical; X is an oxygen or sulfur atom or the divalent radical ##STR2## wherein R.sub.3 is a hydrogen atom or an alkyl, aryl, alkylaryl or arylalkyl radical; at least one of the substituents R.sub.1, R.sub.2 and R.sub.3 having an amphiphilicity-imparting number of carbon atoms.