Experimental Determination of Equilibrium Rate Constants

Quantitation of equilibrium constants of self-association needs the fraction of free monomers that are present in dilute solutions of known concentration. Suitable assumptions were made such as the intensity of the free hydroxyl band as a measure of the free monomers. The intensity from absorbance of the isolated hydroxyl band, I is related to the absorptivity coefficient, e, the concentration, c, and the path length I by the Beer-Lambert law  

Two dimensionless equilibrium constants were found necessary to adequately describe the self-association of OH groups. The formation of dimers with an equilibrium rate constant of K2 and higher repeat multimer complex with an equilibrium rate constant of K/. 

Coleman and Painter [5] have developed an iterative least squares fitting procedure to obtain the best fit of experimental data. The fraction of OH groups that participate in hydrogen bonding is related to the dimensionless equilibrium rate constants K2 and in Equation (4.22)  

The difficulty experienced using this method is when systems such as polyvinyl phenol (PVPh) and ethylenevinyl alcohol (EVOH) need to be measured. The 

Intermolecular association between two functional groups located in different polymers can be accounted for as follows  

---