I am not convinced concerning the reason people believe in a simple correlation (possibly to measure equilibrium contact angle) especially for not very accurate performed measurements but the response in the link might give you some insides and different opinions.

https://www.researchgate.net/post/What_is_the_best_method_to_measure_the_Surface_Energy_of_the_metal_oxide_thin_films?_iepl%5BviewId%5D=kio2DSiqRz8wqo32cfNcOTaA&_iepl%5Bcontexts%5D%5B0%5D=prfiqi&_iepl%5BtargetEntityId%5D=Q%3A59bcafd948954c88cb7fe8ed&_iepl%5BinteractionType%5D=questionView

To calculate surface free energy (SFE) you need information about contact angle as well as the liquids used for contact angle measurements.

There are several different theories available for surface free energy calculations but most common ones divide SFE to either two or three components. If divide into two, the total surface free energy is the sum of polar and dispersive components. To calculate those, you need to measure the contact angle with polar liquid (most commonly water) and completely dispersive liquid (di-iodomethane is mostly used). If you use three component approach, then the polar part is further divided into acid and base components. In this case third contact angle measurement is need (most commonly ethylene glycol is used).

For further information, see the attached link.  

http://www.biolinscientific.com/zafepress.php?url=%2Fpdf%2FAttension%2FTheory%20Notes%2FAT-TN-04-Surface-free-energy-theory.pdf

It is not quite clear which surface free energy you want to obtain: LG, SL or SG? G=gas, L=liquid, and S = solid phase.

LG=surface tension, well known, can be done with classical techniques.

SL: solid liquid interfacial tension is difficult to obtaine; but changes in the SL interface free energy follow from adsorption studies by application of Gibbss-law of interfacial tensions.

SG: solid gas surface tension can be approximated for low energy surfaces (polymer type) by using contact angel measurements in combination with a model for the SL interface that specifies the type of interactions that prevail in the SL interface. Several classical (simple) models are available in literature that make such an assumption.

The rule of Antonov is one of them. Other classical models are the Fowkes model, the model of Good and Girifalco (worked out by Wu et al) and the model of Van Oss which is an extention of the Fowkes model.

The Antonov and classicla Fowkes model don't take polar interactions into account. The Good and Girifalco model formally also considers polar interactions but involve an additional parameter that is not easily available in practice.

The Van Oss method explicitly adds the polar interactions but a series of contact angle measurements has to be carried out with different standard liquids.

See for more detail and references: L.K. Koopal / Advances in Colloid and Interface Science 179–182 (2012) 29–42 and L.K. Koopal,  Interface Science, chapters 3 and 13. These refs are available through Research Gate.

Thank you all for your reply.

Thank you Dr. Koopal. I wanted to calculated surface energy of liquid-solid interface.

Thanks every one for all your guide and assistance

I'm wondering about the method to measure the polar/dispersive part of a liquid. How to exactly obtain these parameter? I can find some article which have tables showing the magnitude of as mentioned property but they do not reference to any literature! I can not find a source or handbook about how we can measure the polar/dispersive component of surface tension for a liquid like water, hexane, diiodomethane, etc. I can barely see different numbers for every liquid on different papers.

Thanks any body who lead me to the light :)

@ Sepideh Rahimi

You Can Measure Surface free energy by using contact angle.

First you have to measure contact angle by polar liquid and then you have to measure contact angle by non polar liquid ( According to literature its Diiodo methane). Its the way how you can Calculate Surface free energy.

Wetting envelop is very crucial in this the values that vary inside the wetting envelop that Combination polar:Disperse liquid will proper wet that surface.

Bhupendra Singh Company

Dear Sir/Madam,

Thanks for the time and answer.

I'm getting confused a little. I can measure the contact angle of water and other normal liquids. The question is what is the Standard procedure to obtain the surface tension of a common liquid e.g. water, Hexane, Diiodo methane, etc. I have a source of these materials but it seems the surface tension is different from the literature. Also, I've found the magnitude of this property on Kruss GmbH and other papers that are different themselves. I can refer to the published literature if needed.

I just do not know which one to trust and compare with my measurement.

Regards

Dear Sepideh Sadat Rahimisheikh

Most typically people rely on literature values of surface tension components. For diiodomethane 50,8 mN/m (completely dispersive) and for water 51 mN/m (polar) and 21,8 mN/m (dispersive). However, as you pointed out these values can vary depending on the source of the liquid, how it is stored, what is the temperature etc.

It is possible to measure the polar and dispersive components of the liquid. There are standards written that explain the procedures (see ISO 19403-4:2017 and ISO 19403-5:2017). In the first standard a completely dispersive reference liquid and OWRK theory is used to measure and calculate the dispersive part of the liquid. In the second one a completely dispersive reference surface is utilized and contact angles are measured to determine the dispersive part of the surface tension. Here, we need to note that both of these methods require a reference liquid/surface with the known dispersive part. Also the measurements needed to very carefully done to avoid additional sources of error.

With this said, I think it is useful to check that the total surface tension is close to the literature value before conducting the contact angle measurements (this is actually done automatically by some modern measurement software). But to define the polar and dispersive components for the liquids before each contact angle measurement seems quite time consuming.

I hope this clarifies the issue.

Dear Susanna Lauren ,

I appreciate your guide and help.

It was truly helping me using the standard test methods. Thank you very much.

Thank you for the message

Sepideh Sadat Rahimisheikh and other researchers,

Liquids surface tension and its components can be measured when drop of that liquid [with known surface tension (σl)] is made on solid of known polar and dispersive components (mostly PTFE solid with 0 polar component σsp =0 and σsd = 18 mN/m), then

σld =((σl×(Cosθ+1))^2)/(4×σsd) Eq-1

and

σlp=σl-σld

Reference Eq

(σl ×(Cosθ+1))/(2×(σld)^0.5)=[(σsp)^0.5 *(σlp)^0.5 ]/(σld)^0.5 +(σsd)^0.5 (so for PTFE σsp =0 and this Eq become Eq-1)

:-)