Nanocomposites of polyurethane elastomers were formed by dispersing nanoclay fillers, Laponite, via solvent exchange methodology. The used polyurethanes are based on hard segment, diphenylmethane diisocyanate and soft segment, poly(tetramethylene ether) glycol, and have varying hard segment ratios and different chain extenders. Different contents of the Laponite were used in the formulation. The morphology, themomechanical properties, tensile properties of the nanocomposites have been explored by transmission electron microscopy, atomic force microscopy, wide angle X-ray diffraction, dynamic mechanical analysis, differential scanning calorimetry and Zwick mechanical testing. The nanocomposites show good dispersion of clay fillers and highly enhanced moduli depending on the clay loadings; heat distortion temperatures are seen to shift to higher values. The correlation of architectures of the elastomers, morphology and contents of the clay fillers with thermomechanical behavior will be described in some details.