Authors: Sosale Chandrasekhar
Comments: 18 Pages.
Macromolecular aggregation and mechanical strength characterize polymer behavior, but apparently remain enigmatic: small molecules prefer to be solvated but macromolecules prefer to aggregate. This is a consequence of the enormous loss of solvent entropy attending macromolecular solvation. The additivity of weak (e.g., van der Waals) forces in a macromolecule cannot explain aggregation, as the accompanying entropy loss would also be additive. However, even this would be overshadowed by the loss of solvent entropy in the case of its solvation. A thermodynamic basis for the aggregation, however, needs a reassessment of the van der Waals equation of state, a reinterpretation of the coefficient ‘a’ suggesting that the van der Waals force may be stronger (~15 kcal mol--1) than believed. Its manifestation is normally thwarted by the dominance of entropic effects in the weak interactions. The phenomenal mechanical properties of polymers are explicable by the above reassessment of current ideas.