A great deal of work has been done relating the structures in elastomeric block copolymers to their physical properties, with most of this work being done on styrene–butadiene systems. The subject has been reviewed by several authors. It is the purpose of this study to relate this previous work to new thermoelastomer systems. The structure of some non-block, partially hydrogenated polymers prepared by Duck et al. and a poly(dimethylsiloxane-β-α-methylstyrene), as determined via small angle X-ray scattering and calorimetric properties, were compared with their dynamic mechanical properties.