Model diblock copolymers of poly(butadiene-1,3) and poly(dimethylsiloxane) (PB-b-PDMS) of different compositions were synthesized by the sequential anionic polymerization (high vacuum techniques) of butadiene 1,3 and hexamethyl(ciclotrisiloxane), (D3), monomers. The block copolymers were characterized by nuclear magnetic resonance (H-1 and C-13 NMR), size-exclusion chromatography (SEC), Fourier Transform infrared spectroscopy (FTIR), and Small Angle X-ray Scattering (SAXS). SEC combined with H-1 NMR analysis indicate that the PB-b-PDMS copolymers exhibit molar masses between 5000 and 13000 g/mol, narrow polydispersity index (M-w/M-n), and chemical compositions ranging from low to intermediate siloxane content. According to SAXS experiments, at room temperature the model block copolymers present morphological arrangements that vary from disordered and body-centered-cubic packing of spheres, to hexagonally packed cylinders and lamellar structures. (C) 2015 Elsevier Ltd. All rights reserved.