Effect of Tacticity on London Dispersive Surface Energy, Polar Free Energy and Lewis Acid-Base Surface Energies of Poly Methyl Methacrylate by Inverse Gas Chromatography

Abstract

This research was devoted to study the effect of the tacticity on the surface physicochemical properties of PMMA. (1) Background: The determination of the surface free energy of polymers is generally carried out by inverse gas chromatography (IGC) at infinite dilution. The dispersive, polar and surface acid-base properties of PMMA at different tacticities were obtained via IGC technique with the help of the net retention time and volume of adsorbed. (2) Methods: The London dispersion equation was used to quantify the polar free energy of adsorption, while the London dispersive surface energy γsd(T) of PMMAs was determined using the thermal model. (3) Results: The results showed non-linear variations of γsd(T) of atactic, isotactic, and syndiotactic PMMAs with three maxima characterizing the three transition temperatures of PMMAs. The obtained values of the enthalpic and entropic Lewis’s acid-base parameters showed that the basicity of the atactic PMMA was about four times larger than its acidity. (4) Conclusions: A large difference in the behavior of the various PMMAs was proven in the different values of the polar acid and base surface energies of the three PMMAs with an important effect of the tacticity of PMMA on its acid-base surface energies.

Keywords

• London dispersion equation
• recovery fraction
• polar enthalpy and entropy
• Lewis’s acid-base parameters
• transition temperatures
• intermolecular separation distance