Various blends composed of pure polystyrene (PS) and modified PS [amino-functionalized polystyrene (PS–NH2)] were prepared with a new aromatic polyamide obtained through the polycondensation of 1,5-diaminonaphthalene and 1,4-phenylenediamine with isophthaloyl chloride. The variation in the morphological and thermophysical profiles in the two blend systems with aramid loading were investigated. The amine functionality introduced to PS enhanced its compatibility with the polyamide because of the formation of an aramid-graft-PS copolymer. The grafting, hydrogen bonding, and phenylene-ring (π–π) stacking between the chains of the two components finally nurtured self-assembled nanostructured blends. A strong compatibilizing effect was observed for the 50, 60, and 70 wt % aramid blends, where an exceptionally inimitable cocontinuous self-assembled morphology was formed by PS–NH2/aramid. Significant developments in the morphology along with thermal and mechanical stability were observed for the reactive PS/aramid system. The most favorable mechanical and thermal data supported by the finest nanostructure were observed with 70 wt % polyamide addition. Future prospects may involve the formation of nanotemplates and nanostructured membranes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39954.