Dispersão de nanopartículas de látex em um cristal líquido liotrópico / Dispersion of nanoparticles of latex in the lyotropic liquid crystal

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

In this work, we studied the dynamics of agglomeration and dissociation of latex particles when inserted into a lyotropic liquid crystal. This liquid crystal is a ternary system formed by potassium laurate, decilamonium chloride and water, presenting uniaxial calamitic and discotic nematic phases (NC e ND, respectively) and a biaxial nematic phase NB. The latex particles have diameter of 100 nm and particles with different surface treatments were tested. It was observed that in the NC e NB phases the latex particles form agglomerates, however in the transition to the ND phase, the particles disperse in the medium. In the temperature domain of the biaxial nematic phase the agglomerates increase in size, become anisometric and oriented along parallel to the orientation of the medium. Two phase diagrams were built by varying the particle concentration dispersed in the liquid crystal and by varying the relative composition of surfactants of the liquid crystal. X rays diffusion experiments have shown that the average distance between the micelles in the host medium are not affected by the presence of the latex particles and remain the same in all nematic phases. Rheology studies were also performed and it was found that the viscosity of the system is affected by the presence of the particles. The observed phenomenon are interpreted taking into account the orientational fluctuations of miceles in the different nematic phases.

ASSUNTO(S)

dispersão coloidal liquid crystal reology cristais líquidos cristais líquidos liotrópicos colloidal dispersion realogia em cristais líquidos colóide anisotrópico lyotropic liquid crystal anisotropic colloid liquid crystal

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