I'm working on experimental aspect of weak polyelectrolyte (polyacrylic acid). Can anyone please suggest me whether the average spacing between the monomers changes by altering pH of the medium? If so, plesae suggest me how to calculate it?
See the formula in the file. Draw a series of ionized monomer units. Calculate their distance along the lengths of bonds and angles on the plane. Then draw when they are as far away as possible. Calculate the lengths of ties and angles. Take the mean value.
You need to determined the degree of charge of your polymer as a function of pH. The easiest thing is to perform a potentiometric titrations. Once you know the fraction of charged units you can easily calculate the mean distance between the charges.