Effect of surfactant on PDLC films with and without permanent memory effect

Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica

The main goal of this work is to optimize the performance of the PDLC films with the introduction of an additive, in this case the triton X100. The polymer matrix of the PDLC is based on monomers, such as Tri(ethylene glycol) dimethacrylate and poly(ethylene glycol) dimethacrylate with molecular weight of 875 which were thermal polymerized using α,α-azobisisobutyronitrile as initiator. Different aspects were investigated, such as the study of the dynamics of the transition ON/OFF state using a high-frequency alternate voltage and the attempt to minimize the liquid crystal anchorage force to the polymer matrix observed. The polymer morphology and the composites synthesized were analyzed by scanning electron microscopy. The PDLC films were also analyzed resorting to additional studies of differential scanning calorimetry, polarized optical microscopy and Fourier transform Infrared spectroscopy . Finally, the kinetic behavior of the PDLC films was studied. This part of the work was done with the goal to understand what was the impact of the increase amount of TX100 on the orientation and disorientation time of the LC molecules. Additionally, a fitting model was developed in order to describe the orientation and disorientation kinetic of the system. It was verified that the increase amount of TX100 modifies the initial anchorage force of the LC molecules to the polymeric matrix, decreasing it. This reflects on the increase of the permanent memory effect and decrease of the E90 of the PDLC films, verified also with the decrease of the average elastic constant, K, of the PDLC film. On this work, the best value for the permanent memory effect was 96% with an E90 of 2V/μm. However, this work also demonstrates that the kinetic of the system is independent of the amount of TX100, which means that the LC molecules orientate and disorientate at practically the same time with or without additive.