self-avoiding random walk.
Most water-soluble polymers have 04b4 1 ð 0 : 5 5w5 0 Þ.
This implies that for a linear homopolymerrm&rgH 6 &bðn^0 Þn n^0 >* 25 ð 6 : 4 Þ*wherenvaries between 0.5 and 0.6. Addition of small-molecule
solutes (salts, sugars, alcohols, etc.) in high concentrations may
significantly affectb. Forbvalues only slightly smaller than zero,
most polymers are insoluble. Notice that an ‘‘ideal’’ solvent
actually is a fairly poor solvent. Solubility is discussed in Section
6.5.1.FIGURE6.5 Calculated average frequency distribution of monomers about the
center of mass of a polyethylene molecule of 2000 CH 2 monomers, forb¼ 0 :46 nm.
Nis the number of monomers per unit volume per unit ofR(arbitrary scale).Ris the
distance from the center of mass. Examples for an ideal solventðb¼ 0 Þand a good
solvent ðb¼ 1 Þ. rg is the radius of gyration. (Adapted from Tanford; see
Bibliography.)