The N-(n-alkyl)pyrrolidones are low vapor pressure polar solvents which are surface active in aqueous solutions. From measurements at low surface pressures and low concentrations the two-dimensional second virial coefficients B2(T) at the air/water interface are obtained for the series of even-numbered alkyl substituents from ethyl to octyl. At 25 °C, B2(T) is positive for the ethyl compound and becomes increasingly negative as the chain length increases. The effect of temperature on B2(T) is unusual, increasing temperature leading to more negative B2(T) values. The virial coefficients, heats of adsorption, and Traube coefficients are discussed in terms of molecular packing, chain-chain van der Waals attraction, and the interaction of the chains and large molecular dipoles with water.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces