Polystyrene (PS)/cetyltrimethylammonium bromide (CTAB)/silica composites were prepared by CTAB-catalyzed in-situ polymerization of high internal phase emulsion gels (HIPE gels) at room temperature. The room temperature approach in HIPE gels yielded mono-dispersed PS/CTAB/silica spherical composite particles with sizes of 121 and 155 nm. The complex microscopic internal structures of these particles were determined with the use of temperature-modulated differential scanning calorimetry (TMDSC). CTAB, in particular, was identified in different environments within the composite particles based on its different crystallization temperatures observed on cooling: a thin layer at the surface of the fumed silica (T-C,T-CTAB = 74 degrees C), multilayers (T-C,T-CTAB = 82 degrees C), and a mixed PS/CTAB shell (TTC,CTAB = 65 degrees C). The amounts of each component were estimated from the enthalpies of the crystallization. The PS/CTAB mixed shell contained CAB on the surface of the particle plus internal CTAB domains. (C) 2015 Elsevier Inc. All rights reserved.