Anomalous elasticity of polymer cholesterics

We show that polymer cholesterics have much longer pitches than comparable short molecule cholesterics, due to their anomalous elasticity. The pitch P of a chiral mixture with concentration c near the racemic (nonchiral) concentration c* diverges similar to |c-c*|-, with =1.430.04 (for short molecule cholesterics, =1). The short molecule law is recovered for polymers of finite molecular length once the pitch is longer than a length that diverges similar to with =0.670.01. Our predictions could be tested by measurements of the pitch in DNA. © 1995 The American Physical Society.