Phase transition and optical behavior of PVP-MBBA microfibers

Abstract

This study discusses the fabrication and characterization of optically responsive microfibers with uniaxially ordered nematic liquid crystal molecules at their core. The liquid crystal microfibers were electrospun from a solution of polyvinylpyrrolidone (PVP) and N-(4-methoxybenzylidene)-4-butylaniline (MBBA). A study of phase transition and optical behavior was performed using optical observation by polarized optical microscope, and intermolecular interaction was investigated using Fourier transform infrared (FTIR). The diameter, orientational order of the fibers and light intensity that passed through the fibers depended on the MBBA concentration during the electrospinning process. The nematic-isotropic temperature (T NI) of PVP-MBBA microfibers shifted lower from the T NI of MBBA. Meanwhile a reverse correlation between MBBA concentrations and phase transition was found in the isotropic phase; a significant increase in temperature rate and response time was occurred with small weightage of MBBA. FTIR measurement confirmed that the liquid crystal molecules were self-phase separated from the PVP chains in the fibers.