An interactive guide to the theory and application of HSP.
Hansen Solubility Parameters (HSP) provide a method for predicting the solubility of materials. The core idea is that the total cohesive energy of a substance can be divided into three parts: dispersion, polar, and hydrogen bonding forces. Materials with similar HSP values are likely to be miscible.
Represents the energy from nonpolar van der Waals forces. These temporary fluctuating dipoles exist in all molecules.
Represents the energy from permanent dipole-dipole interactions. This is significant for polar molecules.
Represents the energy from hydrogen bonds, a strong type of dipole-dipole interaction involving H, N, O, or F.
The three parameters (δD, δP, δH) form a 3D coordinate system called the Hansen Space. Each material can be plotted as a point in this space. For a given solute, we can define a "solubility sphere" with a radius R₀. Any solvent that falls inside this sphere is predicted to be a good solvent for that solute.
The distance (Ra) between a solute (1) and a solvent (2) in Hansen Space is calculated using a modified Euclidean distance:
Ra² = 4(δD₁ - δD₂)² + (δP₁ - δP₂)² + (δH₁ - δH₂)²
The Relative Energy Difference (RED) number determines solubility:
RED = Ra / R₀
This interactive 3D chart visualizes the Hansen Space. Each point represents a solvent. The central sphere represents the solubility region for a sample solute (e.g., a polymer). Solvents inside the sphere are good solvents, while those outside are poor solvents. You can rotate, pan, and zoom the chart. Hover over points to see their details.
Solute: Sample Polymer
Radius (R₀):
| Solvent | Ra | Status |
|---|
HSP is a versatile tool used across many industries to predict material interactions, reducing costly trial-and-error experiments. Below are some key areas where HSP provides critical insights for formulation, product development, and problem-solving. Click on each category to see specific examples.
The development of Hansen Solubility Parameters marked a significant step forward from single-parameter models, providing a more nuanced way to understand molecular interactions. This timeline highlights the key milestones in its conception and evolution.
Dr. Charles M. Hansen introduces the "Three Dimensional Solubility Parameter" concept in his Ph.D. thesis and in a series of articles in the Journal of Paint Technology. This work was foundational for the paint and coatings industry.
The use of HSP expands beyond coatings into diverse fields like pharmaceuticals, cosmetics, and environmental science as more researchers and industries recognize its predictive power for a wide range of solubility and compatibility problems.
The release of the "Hansen Solubility Parameters in Practice" (HSPiP) software makes the methodology widely accessible. It provides a large database of HSP values and tools to calculate and visualize solubility, popularizing its use globally.
HSP is now applied to complex systems like nanomaterials (graphene, nanotubes), biological systems (DNA, proteins), and for designing sustainable, "green" solvent systems, demonstrating its enduring relevance and adaptability.