Layered Double Hydroxide (LDH)-filled nanocomposites were processed from film-forming latexes synthesized by macroRAFT-assisted encapsulating emulsion polymerization (REEP). The microstructure and thermomechanical behavior of the polymer matrices and corresponding nanocomposites were investigated by TEM, FIB-SEM, SAXS and DMA. Strong ionic interactions created between acrylic acid groups induce lamellar nanostructuration of the P(AA-BA)-b-P(MA-BA) diblock copolymer matrix and are responsible for a high Young's modulus in the rubbery state that increases with the length (i.e., the molar mass) of the P(AA-BA) blocks. When filled with 16 wt% of LDH, the intrinsic structure of the matrix is lost and the mechanical behavior of the nanocomposites is solely driven by the LDH dispersion and ionic interactions. Two types of percolation (i.e., mesh size of the LDH network and mechanical reinforcement) have been achieved by playing with the degree of segregation of the LDH nanoplatelets within the material.