molarity of a solution is the "number of moles of the solutes dissolved in one litre of the solvent".
if i want to prepare 1Molar solution of sodium hydroxide, i will dissolve 40 gms of sodium hydroxide in 1L of water.
in a similar way, if you want to prepare 1M solution of your polymer and x is the molecular weight of your polymer, then you have dissolve x gms of polymer in 1L of appropriate solvent. in this case, butanol.
ofcourse, in the case of polymer you will be most probably using average molecular weight, since you cannot have a polymer with all the molecules wth the same molecular weight.
you need not confuse with the volume of the solute in case the solute is a liquid. you can go by the weight.