The HSP Sphere in VR

This is a bleeding edge implementation in VR which currently only works on a special WebGL Chrome and Firefox builds (Edge is on its way). It works well with the Vive (with its controllers) and with Oculus Touch. I've put it on-line for those who have the right set-up and willingness to explore.
Get your VR set ready in the WebVR special build then hit the Enter VR button.

Instructions are below the app.

  1. You select objects with the eye pointer - getting an immediate readout of what you are looking at.
  2. Clicking the trackpad immediately teleports you there.
  3. To fly - just look where you want to go and pull the trigger, controlling your speed with the trigger press and direction with right/left trigger.
  4. By clicking the menu button while looking at a solvent you create an optimised blend between where you are and the other solvent, with the % of that solvent in the blend shown along with the HSP and Distance. To get a blend between two specific solvents, teleport to one solvent then look at the other one and do menu.
  5. To choose between 3 different demo spheres, point at the Sphere menu dropdown and select with the trigger
  6. To add another solvent to the view, point at whichever of the two (long) menu dropdowns contains your alphabetical solvent and select with the trigger. This is clunky but the dat.guiVR used does not (yet) have a good way to choose from long scrolling lists.

What the Sphere means

HSP are measured using the Sphere technique. A set of solvents with known HSP is used to test the "happiness" of a test material in the solvents then a sphere is constructed with all the "good" solvents inside it and all the "bad" ones outside. The centre of the sphere is the HSP of the test material and the radius defines its limits of "happiness" for when you want to find other solvent systems to work with it.

If the test material is a simple polymer or crystalline solute then instead of the word "happiness" we would use the word "solubility". However, the technique is perfectly general and the definition of "happiness" varies. For nanoparticles and dispersions the definition might be "remains well suspended". For cross-linked polymers it might be "swells significantly". The point is that the formulator knows what they want for a "happy" formulation so can choose their own definition so that the measured HSP and radius are both meaningful for the given application.

Here we start with the sphere of solubility of one type of polylactic acid (PLA). The centre of the sphere is a reasonable estimate of the HSP of PLA. The radius is rather large because the specific PLA was of modest MWt and crystallinity. In other (unpublished) work we have used a highly crystalline PLA which gave the same central HSP but a much smaller radius. All the good solvents (blue) are inside the sphere (transparent green), all the bad solvents (red) are outside and PLA itself is the green dot in the middle.

The data behind the fit are from a public domain dataset taken from HSPiP. The "Score" is simply 0 for insoluble, 1 for soluble, and the RED is the Relative Energy Distance which is HSP Distance/Sphere Radius, with good solvents <=1 and bad solvents >1.

No Solvent δD δP δH Score RED MVol
524Methylene Dichloride17.007.307.1010.37464.4
481Methyl Ethyl Ketone16.009.005.1010.63590.2
297Dimethyl Formamide17.4013.7011.3010.84177.4
303Dimethyl Sulfoxide18.4016.4010.2010.99671.3
328Ethyl Acetate15.805.307.2010.68198.6
414Hexafluoro Isopropanol17.204.5014.7010.956105.3
754Isoamyl Alcohol (3-Methyl-1-Butanol)15.805.2013.3010.963109.3
255Diethyl Ether14.502.904.6001.078104.7
443Isopropyl Ether15.103.203.2001.006141.8

The official site of Hansen Solubility Parameters and HSPiP software.