The critical concentration of surfactant in clusterization of sodium tetradecyl sulfate (SMS)

sodium dodecyl sulfate (SDS) and sodium decyl sulfate (SDeS) on polyvinylpyrrolidone (PVP) homolog or polyetheleneglycol (PEG) homolog was studied by means of surface tension．There occur bis-transition points or pseudo double-plateau regions in the γ-lgc curves of the above clusterization systems

which means that soft matter clusters are vielded between the two critical concentrations．The two critical concentration values c1 and c2 could be found along with these γ-lgc curves

and they fulfil the relationship of c1＜cmc＜c2. The c1 value of a given surfactant is basically an invariant

which is independent on the molecular weight and concentration of a certain homolog of macromolecule．Moreover the value of c1 is decreased with the increase of hydrophobicity of the surfactant homolog．The relation between lgc1 and n

the number of alkyl chain carbons of a surfactant

is simply decreasing

which can be expressed by linear equations：lgc1=1.58-0.341 n (R2=0.9981)for PVP-ROSO3Na soft clusters and lgcc1=1.38—0.313n (R2=0.9993) for PEG-ROSO3Na soft clusters．Meanwhile the value of c2 is independent on the molecular weight of the polymer under the same polymer concentrations．