For an athermal polymer-solvent mixture forming a lattice, Flory calculated Ω, the combinatorial factor, i.e., the number of possible distinguishable arrangements of the chain (polymer) and the monomer (solvent) [3,5]. From this combinatorial factor, Flory found the entropy using Boltzmann’s relation:

S k= B lnΩ (6.1)

where kB is Boltzmann’s constant. The symbol Ω is used frequently in the physics literature, but another symbol, Ωcomb is often used in the physical-chemistry literature. In some articles, W is used instead of Ω.