Practical Ways to Use Hansen Solubility Parameters · 2018-10-25 · for microencapsulation. Here,...
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Practical Ways to Use Hansen Solubility Parameters AIMCAL R2R Conference October 31, 2018 - Phoenix, AZ Dr. Ken McCarthy Clean Room Coating Solutions 151 Flint Locke Drive Duxbury, MA 02332 617-549-4620(C) [email protected] Clean Room Coating Solutions
Transcript of Practical Ways to Use Hansen Solubility Parameters · 2018-10-25 · for microencapsulation. Here,...
Practical Ways to Use Hansen Solubility Parameters
AIMCAL R2R ConferenceOctober 31, 2018 - Phoenix, AZ
Dr. Ken McCarthyClean Room Coating Solutions151 Flint Locke DriveDuxbury, MA 02332617-549-4620(C)[email protected]
Clean Room CoatingSolutions
Practical Ways to Use Hansen Solubility Parameters
Today we will talk about Hansen Solubility Parameters• Background• What they are• Finding a substitute solvent• Determining HSP for a new material• Replacing a good solvent with two bad solvents• Insoluble materials• Drying considerations
Practical Ways to Use Hansen Solubility Parameters
1. BackgroundHansen solubility parameters were developed by Charles M. Hansen in his Ph.D thesis in 1967 as a way of predicting if one material will dissolve in another and form a solution. 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.
Wikipedia
Practical Ways to Use Hansen Solubility Parameters
2. What they are:Specifically, each molecule is given three Hansen parameters, each with the units of MPa0.5:• The energy from dispersion forces between molecules (van der Waals, polarizabilty, correlates with refractive index)• The energy from dipolar intermolecular force between molecules• The energy from hydrogen bonds between molecules.
Wikipedia
Practical Ways to Use Hansen Solubility Parameters
Wikipedia
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 an interaction radius (R0) is given to the substance being dissolved. This value determines the radius of the sphere of that substance in Hansen space and its center is the three Hansen parameters.
Practical Ways to Use Hansen Solubility Parameters
Practical Ways to Use Hansen Solubility Parameters
The Wikipedia description above does not tell us how R0 is determined. We will discuss that determination a little later. In essence, R0 is determined by the solvents that are compatible with, “like”, the material of interest.
Practical Ways to Use Hansen Solubility Parameters
Wikipedia
To calculate the distance (Ra) between Hansen parameters in Hansen space the following formula is used:
Combining this with the interaction radius gives the relative energy difference (RED) of the system:
• RED < 1 the molecules are alike and will dissolve • RED = 1 the system will partially dissolve • RED > 1 the system will not dissolve
The distance between a solute and a solvent determines solubility.
Practical Ways to Use Hansen Solubility Parameters
Professor Steven Abbott, in conjunction with others, has developed several apps that make the use of Hansen solubility parameters much more accessible to workers in this field. This presentation will explore the power present in these apps and show how they can be used to guide development work in making solutions.
AbbottApps for Solutions and Dispersions Prof Steven Abbott
Steven Abbott TCNF Ltd Visiting Professor University of Leeds
Presentation at the AIMCAL FTC, Oct., 2014www.stevenabbott.co.uk
Solubility Science: Principles and Practice (free book)
Now, we will look at finding a replacement solvent.
Practical Ways to Use Hansen Solubility Parameters3. To find replacement candidates, we use one of the Abbott aps (on the Abbott website, click Practical Science; Practical Solubility; HSP; HSP Basics. Scroll down to HSP Values). Let’s say we want to replace Methylene Dichloride (for health concerns). One way to find a suitable replacement is to click on δH in the top banner, resulting in all of the 1,218 listed solvents being ordered by δH.
Practical Ways to Use Hansen Solubility Parameters
3. Finding a Replacement SolventScroll down to Methylene Dichloride (HSP values are 17, 7.3, and 7.1), we find δHis 7.1. (See table) We search for solvents that are “close” to it. Two solvents are near-by, Diethylene Glycol Methyl t-Butyl Ether (HSP values are 16, 7.2, and 7.2) and Ethyl Acetate (HSP values are 15.8, 5.3, and 7.2). Lab dissolution tests can confirm if these solvents are close enough to replace Methylene Dichloride in the solution of interest.
Practical Ways to Use Hansen Solubility Parameters
4. Finding HSP for a New Material (next four slides)We now return to Professor Abbott’s description of spheres (www.hansen-solubility.com; HSP Science; HSP for Beginners) and how they are determined. The calculation and representation of the sphere for a given solute requires the HSPiPsoftware package. Cost for a single license is $1195, with modest volume discounts.
Practical Ways to Use Hansen Solubility Parameters
It has been found that perfect HSP matches are not required for complete solubility, however. If one tests many solvents to see whether they are good or bad for the sticky spruce resin, one finds that the good ones clump together in a three dimensional plot that forms a sphere in the three dimensional HSP space with the HSP of the sticky spruce resin in the middle. There are characteristic differences in HSP in all three parameters that are allowed for good compatibility. These determine the radius of the sphere. Good solvents are within the sphere while bad ones are located on the outside.
Steven Abbott
Practical Ways to Use Hansen Solubility Parameters
Score of 1 – 19 solventsScore of 0 – 8 solvents
Practical Ways to Use Hansen Solubility Parameters
How many solvents should be tested? Most of the cases presented look at 20 - 30 solvents that cover a good part of “HSP” space. You can download a free spreadsheet with HSP functions from:http://www.stevenabbott.co.uk/PracticalSolubility/HSP_Calculations.xlsx This spreadsheet can provide R values for solvents, but does not give the all-important sphere graphically.
Practical Ways to Use Hansen Solubility Parameters
When Charles Hansen first came up with his HSP scheme, he saw that it made a surprising prediction. That two bad solvents (the blue dots in the image) on opposite sides of the HSP Sphere should produce an excellent solvent (green dot in the middle) when mixed 50:50. If his HSP ideas were wrong, then mixing two bad solvents would create another bad solvent. When he did the test his ideas were confirmed - you really can make a good solvent from a mixture of bad ones. This is probably the single most useful idea in the whole of HSP. It allows formulators amazing freedom to combine two solvents that are attractive in terms of cost, safety, odor, volatility etc. but which are poor solvents for the specific system. The blend of the two creates an excellent solvent.
Steven Abbott
5. Replacing a “good” solvent with two “Bad” solvents
Practical Ways to Use Hansen Solubility Parameters
It is important to realize that the HSP of the resultant mixture of solvents is proportional to the volume ratio of the two solvents. So, it is not necessary that the mix be 50:50. That is particularly the case where the solvents are not precisely equally opposite to the solute’s sphere. The only requirement is that the resultant HSP of the mix ends up within the sphere of the solute.
Replacing a “good” solvent with two “Bad” solvents
Practical Ways to Use Hansen Solubility Parameters
6. What about “insoluble” materials?
But how do you characterise the "solubility" parameters of a material that is clearly not soluble? The answer is to be pragmatic. Take a carbon black, attempt to disperse it in ~20 solvents that span HSP space and see whether the carbon black is "happy" or "unhappy" in each solvent. The deliberately unscientific use of "happy" is there to allow the formulator to interpret the experiments in a way that is meaningful to them. For one formulator, a carbon black that is dispersed with a quick swirl of solvent is the only definition of happy. For another the definition might require sonication and then stability measured in weeks. It all depends on the application. But the end result is a set of solvents scored "1" for being good solvents and "0" for those that are bad solvents. Fitting those data via HSPiP quickly tells you if you have a carbon black that behaves relatively simply and gives a good Sphere and a clear value for the HSP.
Steven Abbott
Practical Ways to Use Hansen Solubility Parameters
6. What about “insoluble” materials?
One form of carbon black
HSP: 16, 10, 7
Practical Ways to Use Hansen Solubility Parameters
6. Another form of carbon black
HSP: 20, 11, 12
Practical Ways to Use Hansen Solubility Parameters
6. What about “insoluble” materials?
Comparison of the two forms of carbon black
The two images are HSP fits of a "low" and "high" hydrophilicity carbon black. The HSP values are [16, 10, 7] and [20, 11, 12] respectively. These are real-world data and the different types behave very differently in different formulations. The differences aren't quite what the simple hydrophilic/hydrophobic split might suggest. They are both relatively hydrophilic. But the one with the lower δD values will formulate more naturally into low δD formulations (simple aliphatics) whilst the higher δD will go better into high δD formulations (aromatics, halogens etc.). If all suppliers of carbon blacks were to simply put their HSP values on the data sheets, the harrassed formulator would have a much easier time.
Steven Abbott
Practical Ways to Use Hansen Solubility Parameters
7. Drying Considerations
In this section, Professor Abbott describes how to handle cases where two solvents are being used as a substitute for a given solvent, but also, during the drying process, there is a need to precipitate the solute at a particular time, i.e., for microencapsulation. Here, understanding where the system is in Hansen space is vital to making the correct choice in adjusting the solvent mix to get the precipitation at the right moment. It is also important to consider the evaporation rates of the two solvents. There is an Abbot App for evaporation rates, shown on P. 80 of Solubility Science: Principles and Practice, the free e-book available on Abbott’s web site. The direct link to the app is:
https://www.stevenabbott.co.uk/practical-solubility/solvent-blends.php
Practical Ways to Use Hansen Solubility Parameters
Practical Ways to Use Hansen Solubility Parameters
7. Drying Considerations
Practical Ways to Use Hansen Solubility Parameters
7. Drying Considerations
The idea that the addition of a bad solvent can make a better solvent has an important negative consequence for those who wish to use anti-solvents to precipitate a solute at a chosen moment, e.g. for microencapsulation. If, as in the diagram, we suppose that we have a borderline good solvent then we can precipitate the solute with either of the two bad solvents. The "good" anti-solvent would be excellent because just a small amount will take the system outside the sphere. The "bad" anti-solvent would be a disaster because by adding it, the solubility will actually increase (heading to the centre of the sphere) before decreasing and finally precipitating the solute.
Practical Ways to Use Hansen Solubility Parameters
Today we have talked about Hansen Solubility Parameters• Background• What they are• Finding a substitute solvent• Determining HSP for a new material• Replacing a good solvent with two bad solvents• Insoluble materials• Drying considerations
Practical Ways to Use Hansen Solubility Parameters
Summary
In summary for this presentation, Hansen Solubility Parameters and the Abbott application apps give to formulators and process engineers a lot of valuable insights into how materials interact and can be used in a variety of applications.
Thank YouQuestions?
Practical Ways to Use Hansen Solubility Parameters
AIMCAL R2R ConferenceOctober 31, 2018 - Phoenix, AZ
Dr. Ken McCarthyClean Room Coating Solutions151 Flint Locke DriveDuxbury, MA 02332617-549-4620(C)[email protected]
Clean Room CoatingSolutions
