Thomas Plesnivy

Star-like discotic liquid crystals

Abstract The game of molecular engineering of liquid crystalline systems via a combination of molecular architecture and functionalization of mesogens has opened interesting perspectives in the field of liquid crystals. Here we report on the synthesis and characterization of star-like heptameric triphenylenes. The discotic subunits in these molecules have been arranged in a hexagonal fashion around a central discotic core, thus leading to a new type of molecular arrangement for discotic liquid crystals. These oligomers do not crystallize and combine a well-defined structure with a discotic polymer-like processing.

Induction of liquid crystalline phases in linear polyamines by complexation of transition metal ions

In this paper, we describe the preparation and characterization of polyamine–copper complexes based onN-alkylated polyethyleneimines which were obtained by polymer analogous reduction of the corresponding N-acylated polymers. Liquid crystalline properties of the originating linear polyamides are lost in the resulting polyamines which show a higher conformational mobility. In analogy to low molecular mass azacrown derivatives, the complexation of transition metal ions, here copper(ii), may reinduce liquid crystalline behavior. The structure formation in the liquid crystalline state is discussed based on X-ray investigations.

Self-organization of amphiphilic N-acylated linear polyethyleneimines: investigation of a reversible monolayer collapse

Abstract Poly-N-4-decyloxybenzoylethyleneimine, highly crystalline in bulk, forms a stable monolayer at the air-water interface which undergoes a reversible collapse into a probable bilayer structure at higher surface pressures. We achieved transfer both from the monolayer and “bilayer” region of the polymer film at the water surface onto hydrophilic and hydrophobized quartz supports. Based on X-ray investigations on the deposited Langmuir-Blodgett films, a possible mechanism for the reversible collapse is proposed.

Induction of liquid crystalline phases in N-alkylated poly(ethyleneimine)s by transition metal complexation

A liquid crystalline mesophase is induced by complexation of copper(II) nitrate with an N-alkylated poly(ethyleneimine) obtained by reduction of the corresponding polyamide, in analogy to low molecular mass azacrown derivatives.