One of the goals of our lab has been to demonstrate that is is possible to align large quantities
of gold nanorods using the self assembly of liquid crystals. So far, however, in many liquid
crystal systems the gold nanorods will aggregate which destroys the surface plasmon resonance
that we are hoping to achieve. I have demonstrated in my research that we can use a solution
of cellulose nanocrystals dispersed in water to align large quantities of gold nanorods.
In the case of small molecule liquid crystals like E7 or 5CB, the gold nanorods cause
the director of the liquid crystal to twist around the gold nanorod [11]. These twists of
the director cost energy. However the energy of these defects is minimized when the gold
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nanorod is aligned parallel to the director, which causes the gold nanorods to align parallel
to the director.[11]
Since gold nanorods are much smaller than cellulose liquid crystals, it is unlikely that the
gold nanorods would create energetically costly defects within cellulose based liquid crystals.
However, to predict the alignment of gold nanorods we can again turn to Onsager's theory.
In this case, the translation entropy of both the cellulose and the gold nanorods will be
maximized when the gold nanorods are aligned parallel to the cellulose nanocrystals. However,
this alignment will only happen after a certain concentration of cellulose is reached.