Surface Tension of Homopolymers

The precise value of the surface tension is the result of a number of interactions however, the values for high polymers vary from about 20 mN m for highly hydrophobic materials such as polydimethylsiloxane (PDMS) and polyfluorocarbons to values of the order of 45 mN m for polar materials such as polyesters and polyamides. The surface tension of water has a value of 80 and hence most materials are only mildly hydrophilic. 

As indicated in previous chapters, low molar mass materials can segregate to surfaces and hence the molar mass dependence of the surface tension is an important factor in considering the performance of a polymer material. Wu has proposed that 

Both these relationships are theoretically correct and are extremes of the lattice theory, the indices of the molar mass having the value 2/3 for low molar mass and 1 for high molar mass materials. 

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