Question

What is the molecular weight of polymer such as weight average molecular weight and PDI

Answer 1

Weight averaged molecular weight:

It is the sum of the product of the square of the molecular weights of all the polymeric molecules in a solution with their occurences (frequency), divided by the product of the molecular weights with the occurences (frequency). In a way, the polymer's molecular weight is averaged using a distribution of the molecular weights of the individual polymeric weights themselves.

Mw = {sum (Ni * Mi2)} / {sum (Ni)}

Poly Dispersity Index:

It is the ratio of the weight averaged molecular weight to the number averaged molecular weight.

PDI = Mw / Mn