TY  - JOUR
A1  - Liedel, Clemens
A1  - Lewin, Christian
A1  - Tsarkova, Larisa
A1  - Böker, Alexander
T1  - Reversible Switching of Block Copolymer Nanopatterns by Orthogonal Electric Fields
JF  - Small
N2  - It is demonstrated that the orientation of striped patterns can be reversibly switched between two perpendicular in-plane orientations upon exposure to electric fields. The results on thin films of symmetric polystyrene-block-poly(2-vinyl pyridine) polymer in the intermediate segregation regime disclose two types of reorientation mechanisms from perpendicular to parallel relative to the electric field orientation. Domains orient via grain rotation and via formation of defects such as stretched undulations and temporal phase transitions. The contribution of additional fields to the structural evolution is also addressed to elucidate the generality of the observed phenomena. In particular solvent effects are considered. This study reveals the stabilization of the meta-stable in-plane oriented lamella due to sequential swelling and quenching of the film. Further, the reorientation behavior of lamella domains blended with selective nanoparticles is addressed, which affect the interfacial tensions of the blocks and hence introduce another internal field to the studied system. Switching the orientation of aligned block copolymer patterns between two orthogonal directions may open new applications of nanomaterials as switchable electric nanowires or optical gratings.
KW  - alignments
KW  - block copolymers
KW  - electric fields
KW  - reorientation
KW  - solvent vapor annealing
KW  - polymers
Y1  - 2015
U6  - https://doi.org/10.1002/smll.201502259
SN  - 1613-6810
SN  - 1613-6829
VL  - 11
IS  - 45
SP  - 6058
EP  - 6064
PB  - Wiley-VCH
CY  - Weinheim
ER  -