Main Teaching Research About
Brock University : Physics Department : Thad Harroun : Research  
Maple leaf with neutrons
Mesophases of bicellar mixtures

Click on a picture for a larger version. In each picture, light blue represents the short chain lipid, and red the long chain lipid.

Chiral Nematic - Ribbon-like micelles

Recently, we have discoverd that between 23 C and 50 C, there is a cholesteric phase. We propose that the phase is made up of worm-like, or ribbon-like, micelles, whose nematic director undergoes a spontaneous twist due to the chirality of the lipids.

This phase is has been identified as being bicelles in the past. It ocurs in the phase diagram region with the highest amount of magnetic allignment, as determined by NMR.

chiral nematic of ribbon micelles

Smectic A - Lamellar alpha

Well above the chain melting transition of DMPC, the increased soluability of DHPC leaves too much DMPC in the mesophase to form curved structures. Instead, lamellae are formed. These smectic sheets may be perforated by pores lined by DHPC.

smectic a - lamellar alpha

More mesophases...