Session: PMSE/POLY Poster Session:

The encapsulation of liquid crystals (LCs) within semi-flexible, nano-scale media has potential use for developing flexible photodisplays, electronic devices, and sensors. Here, coaxial electrospinning is used to fabricate mats of nanofibers consisting of a polyvinylpyrrolidine polymer sheath and an azobenzene-doped, low molecular weight, LC core. Irradiation with UV light triggers the photoisomerization of the azobenzene dopant and the subsequent nematic to isotropic phase transition in the LC core. Encapsulation of the liquid crystal within the nanofibers results in precise spatial control over the optical properties of the encapsulated LC. This is used to photochemically generate detailed images patterned into nanofibrous mats that are able to be drawn (or patterned using a photomask) with UV light and erased with visible light. Furthermore, we have shown that the photoisomerization of photochromic surfactants within the polymer sheath can affect the phase behavior of a neat LC core. The effect of the concentration and structure of the photochromic surfactant (i.e. aliphatic tail length, and hydrophilic tail length) on the nematic to isotopic phase transition of an LC are investigated.

Dr. Matthew David Thum

Naval Research Laboratory

Appearances