To improve switching times, especially at low temperatures, one or more reactive liquid crystalline compounds is added to a liquid crystal mixture used in an electroptical system. The electroptical system comprises a PDLC film comprising a liquid crystal mixture forming micro-droplets in an optically isotropic, transparent polymer matrix between 2 electrode layers. The liquid crystal mixture comprises one or more compounds of the formula I wherein R, A1, A2, Z1, Z2, X1, X2, Q, Y and n are as defined herein.