Poly(m-phenylene isophthalamide) (PMIA) is a resistant to high temperatures and chemically stable engineering material. The application as coatings and membranes, however, is limited by its poor interaction with other materials. In this report, we describe the molecular modification of PMIA through reaction with dimsyl sodium and 2-iodine-1-ethanol. The substitution of 58% of amide hydrogen by ethanol (etOH) groups produces a material (MPMIA) able to develop regularly structured films on silicon substrate. The morphology of the films is dependent on the ionic strength of the precursory solution. MPMIA starts a degradation process by losing the etOH group. MPMIA has a better affinity with poly(p-cresolformaldehyde) than with a pristine one, increasing the range of composition in which thermal stability and miscibility are observed. Thin films of these blends have different morphologies that vary from nanometric porous to two-phase microstructured grains, according to the composition. Copyright © 2012 John Wiley & Sons, Ltd.