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Selected Works

Gregory A. DiLisi

1990

Articles 1 - 3 of 3

Full-Text Articles in Physics

Splay Elasticity In An Oligomeric Liquid-Crystal, Gregory A. Dilisi, Charles Rosenblatt, Anselm C. Griffin, Uma Hari Aug 1990

Splay Elasticity In An Oligomeric Liquid-Crystal, Gregory A. Dilisi, Charles Rosenblatt, Anselm C. Griffin, Uma Hari

Gregory A. DiLisi

A magnetically-induced Freedericksz transition was used in conjunction with capacitance techniques to determine the splay elastic constant of the 4,4′-dialkoxyphenylbenzoate monomer ‘5OO5rsquo; [C5H11OC6H4COOC6H4OC5H11] and its dimer. As a function of reduced temperature in the nematic phase, it was found that K 11 of the dimer is only about 20 per cent larger than that of the monomer. Moreover, the values of K 11/S 2 versus reduced temperature, where S is the scalar order parameter, are equal to within experimental noise. These results suggest that for short oligomers Meyer's entropic model for splay elasticity in polymer liquid ...


Behavior Of The Anchoring Strength Coefficient Near A Structural Transition At A Nematic Substrate Interface, Gregory A. Dilisi, Charles Rosenblatt, Anselm C. Griffin, Uma Hari Feb 1990

Behavior Of The Anchoring Strength Coefficient Near A Structural Transition At A Nematic Substrate Interface, Gregory A. Dilisi, Charles Rosenblatt, Anselm C. Griffin, Uma Hari

Gregory A. DiLisi

A nearly symmetric alkoxyphenylbenzoate monomer is found to exhibit a transition from perpendicular to tilted alignment at a lecithin-treated glass substrate several degrees below the nematic-isotropic phase transition. By means of the Freedericksz transition the coefficient B of the anchoring energy has been obtained. It is found that B rapidly decreases, and the tilt susceptibility increases on approaching this transition.


Nematic Electroclinic Effect, Gregory A. Dilisi, Zili Li, Rolfe G. Pescheck, Charles Rosenblatt Dec 1989

Nematic Electroclinic Effect, Gregory A. Dilisi, Zili Li, Rolfe G. Pescheck, Charles Rosenblatt

Gregory A. DiLisi

A tilt 0 of the principal axis of the optical dielectric tensor linear in a transverse electric field was observed for a surface-stabilized nematic liquid crystal. The electroclinic coefficient dOldE was observed to increase rapidly on approaching the nematic —smectic-A phase transition from above. This was not expected, and indicates that the incipient translational order is important to the electroclinic effect. The data are consistent with a critical exponent only over a narrow range of temperature, and in this range the apparent exponent is not that expected from theory. In addition, dielectric data are presented for this transition, and birefringence ...