Enhancement of surface-relief gratings recorded on amphiphilic liquid-crystalline diblock copolymer by nanoscale phase separation

A series of novel amphiphilic liquid crystalline (LC) diblock copolymers (ADLC) consisting of flexible poly(ethylene oxide) (PEO) as a hydrophilic segment and poly(methacrylate) containing an azobenzene (AZO) moiety, are presented . Holographic gratings were recorded for ADLC - P40A37 and surface modulation was enhanced by nanoscale phase separation (NSPS). The holographic gratings can be inscribed at room temperature by two coherent laser beams with low intensities in a short time and subsequent annealing improves the diffraction efficiency (DE) by almost two orders of magnitude. These gratings can be applied to secure information storage since the information can be easily read out by thermal treatment.