Staudingers Rule for Polymer Molecular Weight

Although Albert Einstein is most well known for his work in the theory of relativity and for his analysis of the photoelectron effect, he also developed a foundation [3,4] for the theory of solution viscosity. His initial work was on solutions of colloidal spheres and sugar solutions and that work was limited in application. However, as a result of plastics and synthetic rubber being developed during WWll, the field of Polymer Science emerged with great significance to chemical industry. 

Initially, the application of viscosity measurements to polymer solutions extended the relationships derived by Einstein for colloid solutions. While colloids might be assumed to be roughly spherical, polymer molecules can be flexible, rod-like, or plate-like, so adjustments had to be made. Einstein [4] defined some useful terms. Let -qo be the viscosity of the solvent alone and t be the viscosity of the solution in question. As the solution is diluted, the viscosity will approach the t o 

In 1930 Staudinger [8] proposed to adapt Einstein s formalism to solutes of polymers, which may or may not be spherical, even rod-like, or plate-like in a simple formula known as Staudinger s mle  

The interesting thing about this technique of relating viscosity to molecular weight is that if one can measure the viscosity of various concentrations of polymer in the solvent and plot, both the 

This type of work requires careful laboratory technique, but it is very satisfying to see both lines have the same intercept. Often other types of viscometers are used for this work but the Ostwald viscometer can be used for dilute solutions. Further work by Staudinger and his associates was carried out to find the value of K for various types of polymers, and the relationship was later refined to use two parameters K, a) as in 

---