Crossover effects and molecular mass regions in solutions of worm-like polymers: a new relation for the determination of their statistical segment length, based on the blob model

The study of the viscometric results obtained with a great number of worm-l ike polymer-solvent systems showed that plotting the variation of the logar ithm of the intrinsic viscosity versus the logarithm of the molecular mass of these polymers we observe two crossover points. The first crossover poin t corresponds to a molecular mass equal to the molecular mass of one Kuhn s tatistical segment. The second crossover point appears when we reach the co mplete excluded volume behavior and depends on the quality of the solvent. These two crossover points delimit three molecular mass regions. We indicat e the methods to obtain the statistical segment length of worm-like polymer s in each of those molecular mass regions. A new method is proposed in orde r to obtain the statistical segment length of the worm-like polymers based on the Han's equation (Han CC. Polymer 1979; 20:1083) derived from the blob theory. (C) 2000 Elsevier Science Ltd. All rights reserved.