ABSTRACT
Polymers are gigantic molecules with very large molecular weights. Therefore, even if the molar concentration of a polymer in solution is very small, the weight fraction can be quite large. The polymer can be thought of as a large chain living in the volume of the solvent. The basic process of dissolving a solid polymer in a solvent can be thought of as a two step process in the first of which the ordered solid is changed to a disordered, flexible polymer chain, and the subsequent mixing of this random chain with the solvent. Consider a liquid solvent, say water, separated from a solution, containing various solutes in the same solvent, by a semi-permeable membrane which is permeable to the solvent but not to the solutes. In the accompanying figure representing a standard setup for demonstrating Osmotic Pressure, it is seen that the meniscus of the solution is at a greater height than that of the solvent.
