Hansen solubility parameter

Hansen solubility parameters were developed by Charles M. Hansen in his Ph.D thesis in 1967[1][2] as a way of predicting if one material will dissolve in another and form a solution.[3] They are based on the idea that like dissolves like where one molecule is defined as being 'like' another if it bonds to itself in a similar way.

Specifically, each molecule is given three Hansen parameters, each generally measured in MPa0.5:

These three parameters can be treated as co-ordinates for a point in three dimensions also known as the Hansen space. The nearer two molecules are in this three-dimensional space, the more likely they are to dissolve into each other. To determine if the parameters of two molecules (usually a solvent and a polymer) are within range, a value called interaction radius (R0) is given to the substance being dissolved. This value determines the radius of the sphere in Hansen space and its center is the three Hansen parameters. To calculate the distance (Ra) between Hansen parameters in Hansen space the following formula is used:

    \ (Ra)^2=4(\delta_{d2}-\delta_{d1})^2+(\delta_{p2}-\delta_{p1})^2+(\delta_{h2}-\delta_{h1})^2  

Combining this with the interaction radius gives the relative energy difference (RED) of the system:

    \  RED=Ra/R_{0}

Uses

Historically Hansen solubility parameters (HSP) have been used in industries such as paints and coatings where understanding and controlling solvent–polymer interactions was vital. Over the years their use has been extended widely to applications such as:

Theoretical context

HSP have been criticized for lacking the formal theoretical derivation of Hildebrand solubility parameters. All practical correlations of phase equilibrium involve certain assumptions that may or may not apply to a given system. In particular, all solubility parameter-based theories have a fundamental limitation that they apply only to associated solutions (i.e., they can only predict positive deviations from Raoult's law): they cannot account for negative deviations from Raoult's law that result from effects such as solvation (often important in water-soluble polymers) or the formation of electron donor acceptor complexes. Like any simple predictive theory, HSP are best used for screening with data used to validate the predictions. Hansen parameters have been used to estimate Flory-Huggins Chi parameters, often with reasonable accuracy.

The factor of 4 in front of the dispersion term in the calculation of Ra has been the subject of debate. There is some theoretical basis for the factor of four (see Ch 2 of Ref 1 and also.[6] However, there are clearly systems (e.g. Bottino et al., "Solubility parameters of poly(vinylidene fluoride)" J. Polym. Sci. Part B: Polymer Physics 26(4), 785-79, 1988) where the regions of solubility are far more eccentric than predicted by the standard Hansen theory.

HSP effects can be over-ridden by size effects (small molecules such as methanol can give "anomalous results").

It has been shown that it is possible to calculate HSP via molecular dynamics techniques,[7] though currently the polar and hydrogen bonding parameters cannot reliably be partitioned in a manner that is compatible with Hansen's values.

Limitations

The following limitations were acknowledged by Charles Hansen:

See also

References

  1. Hansen, Charles (1967). The Three Dimensional Solubility Parameter and Solvent Diffusion Coefficient and Their Importance in Surface Coating Formulation. Copenhagen: Danish Technical Press.
  2. Hansen's thesis (note that values given are not in SI units)
  3. Hansen, Charles (2007). Hansen Solubility Parameters: A user's handbook, Second Edition. Boca Raton, Fla: CRC Press. ISBN 978-0-8493-7248-3.
  4. C. M. Hansen, "Polymer science applied to biological problems: Prediction of cytotoxic drug interactions with DNA", European Polymer Journal 44, 2008, 2741–2748
  5. M. Belmares, M. Blanco, W. A. Goddard III, R. B. Ross, G. Caldwell, S.-H. Chou, J. Pham, P. M. Olofson, Cristina Thomas, Hildebrand and Hansen Solubility Parameters from Molecular Dynamics with Applications to Electronic Nose Polymer Sensors, J Comput. Chem. 25: 1814–1826, 2004
  6. Patterson, D., Role of Free Volume Changes in Polymer Solution Thermodynamics, J. Polym. Sci. Part C, 16, 3379–3389, 1968
  7. 587.pdf
  8. Abbott & Hansen (2008). Hansen Solubility Parameters in Practice. www.hansen-solubility.com.
  9. Stefanis, E.; Panayiotou, C. (2008). "Prediction of Hansen Solubility Parameters with a New Group-Contribution Method". International Journal of Thermophysics 29 (2): 568. doi:10.1007/s10765-008-0415-z.

External links

This article is issued from Wikipedia - version of the Saturday, April 16, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.