Synthesized N-(4-bromophenyl)-2-methacrylamide (BrPMAAm) and N-(4-fluorophenyl)-2-methacrylamide (FPMAAm) monomers were polymerized via free radical polymerization. Montmorillonite-containing raw clay (NaMT) was purified to obtain pristine clay (SMT). XRF results of the SMT sample showed that sodium amount increased and so it is sodium montmorillonite. Using the SMT and organic surfactant hexadecyltrimethylammonium bromide (CTAB), organoclay (OSMT) was synthesized. d(001) interlayer distances were 1.4967 nm and 2.0439 nm for SMT and OSMT, respectively. Composites of BrPMAAm and FPMAAm monomers were obtained using 2%, 4%, 6%, and 10% organoclay by in situ polymerization. Molecular weights for poly(BrPMAAm), poly(BrPMAAm)-10%0SMT, poly(FPMAAm), and poly(FPMAAm)-10%0STM were 91,300, 31,300, 17,400, and 23,700, respectively. Thermal properties of the nanocomposite were also developed when compared to the pure homopolymer. The beginning thermal decomposition temperature of nanocomposites was shifted to higher temperature. An exfoliated structure was found for the nanocomposites.