Kuhn length

The Kuhn length (after the Swiss physical chemist Hans Kuhn , who calls the Kuhn length in his textbook Principles of Physical Chemistry "statistical chain element" ) is a measure of the stiffness of a polymer : ${\displaystyle l}$

${\displaystyle l={\frac {L}{N}}}$

It is

• ${\displaystyle L}$in the context of the Freely-Jointed-Chain-Model the contour length in which the molecule can be regarded as completely stretched, ie as "straight"
• ${\displaystyle N}$ the number of stiff pieces.

DNS has e.g. B. a Kuhn length of about 100  nm . In the case of semi-flexible chains, as described by the wormlike chain model , the Kuhn length corresponds to twice the persistence length :

${\displaystyle l=2\cdot l_{ps}}$

Individual evidence

1. ↑ not his namesake Werner Kuhn , also a Swiss physical chemist who u. a. researched polymeric materials.
2. ^ Hans Kuhn , Horst-Dieter Försterling, David H. Waldeck: Principles of Physical Chemistry , 2nd Edition, Wiley, Hoboken, 2009.