A phenomenological one-parameter equation of state for osmotic pressures of PEG and other neutral flexible polymers in good solvents.
We present a phenomenological one-parameter scaling equation of state that accurately represents osmotic pressures of neutral flexible polymers in good solvents from the dilute through the semidilute regime. The equation comprises a sum of scaled van't Hoff and des Cloizeaux terms including a fitted parameter alpha, the "crossover index", which encapsulates all chemical specificity and determines the relevant prefactors. Strikingly different values of alpha are found for the two very different systems poly(ethyleneglycol)/water (PEG) and poly(alpha-methylstyrene)/toluene (PAMS). Alpha-dependent rescaling collapses both data sets to a simple one-parameter scaling function. The fact that the anomalous system PEG/water and the canonical system PAMS/toluene can both be described by the same equation of state attests to the robustness of the polymer-scaling concepts introduced by de Gennes.
Cohen
J A
JA
Laboratory of Physical and Structural Biology, PPB, NICHD, NIH, Bethesda, Maryland 20892-0924, USA. jcohen@pacific.edu
Podgornik
R
R
Hansen
P L
PL
Parsegian
V A
VA
D009997:Osmotic Pressure; D011092:Polyethylene Glycols / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013343:Styrenes / Q000737:chemistry*; D014050:Toluene / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
D012997:Solvents; D013343:Styrenes; D014867:Water; C027142:vinyltoluene; D014050:Toluene; D011092:Polyethylene Glycols