Isothermal Titration Calorimetry Reveals Surfactant Adsorption on Nanoparticles

Strategic Insights -

Researchers at the Max Planck Institute for Polymer Research in Mainz, Germany, have used isothermal titration calorimetry to study the adsorption of sodium dodecylsulfate (SDS) surfactant on different sized pure and carboxy functionalized polystyrene nanoparticles. The study found that the adsorption heat depends on the chemical composition of the polymer and the particle size, and provides information about the surface coverage with surfactant and the number of additional adsorbed molecules per particle.

Key Takeaways:

  • The adsorption of SDS surfactant on nanoparticles increases from 0.3 molecules per nm² for 50 nm particles to 8.5 molecules per nm² for carboxy functionalized particles with diameters larger than 160 nm.
  • The area occupied per SDS molecule after adsorption decreases as the number of carboxylic groups increases, indicating a more efficient packing of surfactant molecules on the particle surface.
  • The adsorption process was also monitored by zeta potential measurements, which showed an increasing potential during the adsorption process.
  • The researchers found that the chemical composition of the polymer and particle size both affect the adsorption heat, surface coverage, and packing density of surfactant molecules.
  • The study provides valuable insights into the behavior of surfactants on nanoparticle surfaces, which is relevant for applications in emerging technologies such as nanotechnology.

Statistics:

  • 0.3 molecules per nm²: adsorption of SDS on 50 nm particles
  • 8.5 molecules per nm²: adsorption of SDS on carboxy functionalized particles with diameters larger than 160 nm
  • 3-14: page numbers for the published study in Colloid and Polymer Science

Sources:

  • A. Hamburger and colleagues, "Influence of size and functionality of polymeric nanoparticles on the adsorption behavior of sodium dodecyl sulfate as detected by isothermal titration calorimetry," Colloid and Polymer Science, 2011;289(1):3-14
  • Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, GERMANY