Effects of progressive addition of oxyethylene groups on the thermodynamic properties of pyrrolidin-2-one and Tritons

The apparent molar volumes and molar isentropic compressibilities of pyrrolidin-2-one (PY) with Triton X-45 (TX-45), Triton X-114 (TX-114), Triton X-100 (TX-100), Triton X-405 (TX-405) have been determined at 303.15 K. Excess molar volume VE is negative throughout the composition range and follows the order TX-45 > TX-114 > TX-100 > TX-405. Molar isentropic compressibility KS and its excess values KSE have been obtained by combining the ultrasonic velocity and excess volume data. The deviations in KSE are negative for TX-45, TX-114 and TX-100 and positive for TX-405 and vary in the order TX 405 > TX 100 > TX 114 > TX 45. The results are compared and discussed to gain insight into the interactions between tritons and pyrrolidin-2-one.