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Selected Works

Gregory A. DiLisi

Crystallography

Publication Year

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Full-Text Articles in Physics

Anchoring Strength Coefficient Of A Monomer And Its Dimer At A Polymer-Coated Interface, Gregory A. Dilisi, Charles Rosenblatt, Robert B. Akins, Anselm Griffin, Uma Hari Dec 1991

Anchoring Strength Coefficient Of A Monomer And Its Dimer At A Polymer-Coated Interface, Gregory A. Dilisi, Charles Rosenblatt, Robert B. Akins, Anselm Griffin, Uma Hari

Gregory A. DiLisi

The dialkoxyphenylbenzoate monomer ‘5005’ (C5H11OC6H4COOC6H4OC5H11) and its dimer were aligned parallel to a buffed polyimide-coated glass substrate. A magnetically induced Freedericksz transition in both thick and thin cells was used in conjunction with a capacitance technique to determine the anchoring strength coefficient Was a function of temperature in the nematic phase. It was found that for both monomer and dimer, Wincreases with decreasing temperature. The anchoring coefficient for the dimer, however, was found to be an order of magnitude larger than for the monomer at comparable reduced temperatures. The splay elastic moduli were also determined for both species, and found ...


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.