Insect wax secretion the growth of tubular crystals

Abstract

Filaments of a pure long-chain wax secreted by the wooly alder aphid are shown to represent a previously-uncharacterized, tubular, crystal habit for paraffins. Although this habit is never seen in solution or epitaxial growth of such materials, it requires only a circular closure at the wax secretion site, further growth behavior being controlled totally by van der Waal's intermolecular interactions. The linear paraffin-like wax molecules pack in the filament monolayer envelope with chain axes oriented radially from the filament axis. Elongation of the wax filaments corresponds to the strong interactions along the [110] vectors in the O ⊥ polymethylene chain packing, and stabilization of the filament occurs via strong interchain interactions along [1 10] and [010] in helical paths of opposite chirality.