Polymorphism in monomolecular triglyceride films on water and formation of multimolecular films

✍ Scribed by T. Bursh; K. Larsson; M. Lundquist

• Publisher: Elsevier Science
• Year: 1968
• Tongue: English
• Weight: 480 KB
• Volume: 2
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(68)90036-4

✦ Synopsis

The behaviour of monomolecular films of triglycerides on water has been reinvestigated, and complete phase diagrams were derived. In conflict with earlier reports four different forms of coherent triglyceride monolayers were found, three of which are solid and one liquid expanded. Although the cross-sectional areas and transition points of the condensed phases of the monolayer are very similar to values observed for polymorphic forms of the three-dimensional state, the molecular conformations are fundamentally different. This illustrates the dominating effect of the hydrocarbon chain packing on the physical properties, and the danger in relating structure in monomoleeular films of complex lipids to three-dimensional states on the basis of agreement between transition points and molecular cross-section areas only.

When the monolayers are compressed beyond the collapse points the pressure remains stable until an area is reached which corresponds to a triple chain-length film. It is proposed that two types of molecular conformations occur in triglyceride multifilms on water, with the same conformation in the upper layers as in the crystalline state.