Abstract
Shear can impart a high degree of orientational order to supported block copolymer thin films containing one or more layers of cylindrical microdomains, leading to a striped pattern with a period of tens of nanometers extending over macroscopic (centimeter-squared) areas. Though the as-deposited films have a polygrain structure, after shearing at sufficiently high stresses the only defects which remain are isolated dislocations, and the orientational order can be quite high (nematic or twofold orientational order parameter >0.99, as measured by tapping-mode atomic force microscopy). The effect of isolated dislocations on orientational order is adequately captured by an isotropic elastic continuum model of the structure surrounding the dislocation, producing a linear decrease of order parameter with dislocation density. Even at zero dislocation density, however, the order parameter does not quite reach unity, due to small-amplitude undulations of the cylinders about their axes which persist in the transverse direction over several cylinder periods.
Original language | English (US) |
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Article number | 021507 |
Journal | Physical Review E - Statistical, Nonlinear, and Soft Matter Physics |
Volume | 86 |
Issue number | 2 |
DOIs | |
State | Published - Aug 24 2012 |
All Science Journal Classification (ASJC) codes
- Statistical and Nonlinear Physics
- Statistics and Probability
- Condensed Matter Physics