Because of their strongly anisotropic interactions, dense polymer arrays of DNA and various hetereoproteins with crystalline order perpendicular the average backbone direction have very unusual defects. We discuss first the line-like nature of vacancies and interstitials, which connect polymer free ends. The possible entropically driven proliferation of these strings at a well defined temperature within the crystalline phase is described. [1,2] When polymers are chiral, as is the case for DNA, a bias towards cholesteric twist competes with braiding along the backbone direction. The relevant defects are now screw dislocations, leading either to a tilt grain boundary phase or a new "moire'state" with twisted bond order. [3] In the moire'state, fractal polymer trajectories in the plane perpendicular to their average direction are described by iterated moire'maps of remarkable complexity.
1. J. Prost, Liq. Cryst. 8, 123 (1990).
2. D. R. Nelson, in "Observation and Prediction of Phase Transitions
in Complex Fluids," edited by M. Baus et. al.
(Kluwer, Boston, 1995).
3. R. D. Kamien and D. R. Nelson, Phys. Rev. Lett. 74, 2499 (1995); Phys. Rev. E 53. 650 (1996).