The interaction of monolayers of branched‐chain fatty acids with calcium ions in the underlying solution

Abstract

The effect of calcium ions in the substrate on surface films of α-substituted fatty acids has been investigated. It is shown that the introduction of an ethyl group in the α-positions of lauric, myristic and palmitic acids prevents calcium ions from causing surface films of these acids to become solid and brittle at pH 7.5. Fatty acids with main chains longer than C₁₆ are found to give brittle solid films on substrates containing calcium ions at pH 7.5. The effect on the calcium ion/myristic acid film interaction of variation in the size of the substituent group has also been studied and it is found that even a methyl group has sufficient steric hindrance to prevent film solidification.