Monoacylglycerol and fatty acid monolayers at the air-water interface

The effect of monolauroylglycerol (MAG) and (9:1, 7:3 or 1:1) MAG-lauric acid mixts. on Langmuir monolayers stabilized for 15 min at the air-water interface was examd. at 25, 35, and 45 degrees C, and compressed with barriers moved at 15 mm/min. Surface pressure vs. area isotherms were detd. to evaluate the mol. area, collapse pressure, and elasticity modulus (E) in relation to temp. and MAG-lauric acid mole ratio. The area accessible to each mol. and the collapse pressure fell as temp. was raised. For MAG and its mixts. over 25-45 degrees C, Delta Pi(coll) were resp. 19 and 5 mN/m, regardless of the mole ratio. At Delta T=20 degrees C, Delta E was 12 and 3 mN/m for MAG and for the (1:1) mixt., resp.