Synthesis and structure–property relationships of UV‐curable urethane prepolymers with hard–soft–hard blocks

UV‐curable urethane prepolymers derived from diisocyanates, rigid diols, and polypropylene glycols of different molecular weights and end‐capped with 2‐hydroxylethyl methacrylate were prepared by stepwise addition reactions. These prepolymers have the common structure, HEMA‐hard segment‐soft segment‐hard segment‐HEMA. As the weight ratio of soft segment to hard segment and thus the rigidity varied, the cured films from these prepolymers exhibited a wide range of mechanical and other key properties such as oxygen permeability.