Elastic and mechanofluorochromic hybrid films with POSS-capped polyurethane and polyfluorene

We designed and manufactured elastic hybrid materials consisting of polyhedral oligomeric silsesquioxane (POSS)-capped polyurethane (PUPOSS) and polyfluorene (PF). The POSS group that showed extremelyhigh affinity with conjugated polymers was introduced at the ends of the PU main chain. As a result, homogeneous films were readily obtained through simple mixing with PUPOSS and PF in organic solvents followed by drying. From the series of resulting hybrid films, the sample with 0.5 wt% PF had good elasticity and exhibited photoluminescence (PL) from both locally-excited (LE) and excimer states of PF. Furthermore, owing to elasticity of the PU hybrids, it was clearly shown that luminescent colors were varied by stretching the film samples attributable to alteration of the intensity ratio between the LE and excimer emission. Moreover, similar to conventional hybrid materials, it was shown that hybridization mediated by POSS plays significant roles in improvements of thermal stability, absolute PL quantum yields, mechanical properties and sensitivity. Our strategy based on the POSS-based hybrids is valid not only for tuning physical properties of polymers without spoiling the main features but also for incorporating additional new functions.