Surface and Thermodynamic Properties of Nonionic Surfactants Based on Rosin-Maleic Anhydride and Acrylic Acid Adducts

Abstract

Ester-adduct derivatives of rosin were synthesized by reacting rosin maleic anhydride (RMA) or rosin acrylic acid (RAA) adducts with polyethylene glycol 600 (PEG600), 1000 (PEG1000) or 2000 (PEG2000) and at elevated temperature. These derivatives were evaluated for acid number, FTIR spectroscopy, molecular weight (Mw) and polydispersity. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The surface tension, critical micelle concentration, and surface activities were determined at different temperatures. Surface parameters such as surface excess concentration (Γmax), the area per molecule at interface (Amin) and the effectiveness of surface tension reduction (πCMC) were determined from the adsorption isotherms of the prepared surfactants. Some thermodynamic data for the adsorption process were calculated and are discussed.

Keywords:

• Adsorption
• polyethylene glycol
• rosin derivatives
• surface activity
• thermodynamic parameters

Notes

¹Calculated from ¹H NMR analysis.

²CMC × 10⁴ in (mol dm⁻³).

³γ_CMC in (mNm⁻¹).

*−ΔG_mic and ΔH_mic in kJ mol⁻¹.

*−ΔG_ad and ΔH_ad in kJ mol⁻¹.