We have developed a new approach for the synthesis of polymer nanocomposites using a bifunctional reversible addition-fragmentation chain transfer (RAFT) agent, two types of organo-montmorillonites (O-MMT), such as a non-reactive dimethyldidodecyl ammonium (DMDA)-MMT and a reactive octadecyl amine (ODA)-MMT organoclays, maleic anhydride (MA), and n-butyl methacrylate (BMA) monomers and a radical initiator. This method includes the following stages: (1) synthesis of RAFT intercalated O-MMTs by a physical or chemical interaction of the RAFT agent having two pendant carboxylic groups [S,S'-bis(alpha,alpha'-dimethyl-alpha''-acetic acid) trithiocarbonate] with surface alkyl amines of O-MMT containing tertiary ammonium cation or primary amine groups through strong H-bonding and compexing/amidization reactions, respectively, and (2) utilization of these well dispersed and intercalated RAFT...MMT complexes and amide derivative of RAFT...A-MMT as new modified RAFT agents in radical-initiated interlamellar controlled/living complex-radical copolymerization of MA-BMA monomer pair. Nanostructure and compositions of the synthesized RAFT...MMT complexes and functional copolymer/O-MMT hybrids were confirmed by FTIR, GPC, XRD, thermal (DSC-TGA), SEM, and TEM morphology analyses. This simple and versatile method can be applied to a wide range of monomer/comonomer systems for the preparation of completely exfoliated macromolecular nanoarchitectures. Copyright (C) 2011 John Wiley & Sons, Ltd.