Urethane-methacrylate macromers were prepared by the reaction of tolylene diisocyanate with various glycols, followed by end capping with P-hydroxyethyl methacrylate. A new transparent polymeric material was fabricated by the copolymerization of the macromers with styrene. The thermal behaviors of the new material mere investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis. The samples with different distances between crosslinking points exhibited different thermal behaviors. The sample with short segments between the crosslinking points had a homogenous phase structure and displayed only one glass transition. For the sample with long segments between the crosslinking points, there was a major glass transition and a minor relaxation at high temperature. Surprisingly, the sample with moderate length segments between the crosslinking points showed a novel exothermic peak in the DSC curve. The exothermic peak may have resulted from the formation of a special physical interaction, such as a hydrogen bond.