TY  - JOUR
A1  - Cheng, Xiao
A1  - Böker, Alexander
A1  - Tsarkova, Larisa
T1  - Temperature-Controlled Solvent Vapor Annealing of Thin Block Copolymer Films
JF  - Polymers
N2  - Solvent vapor annealing is as an effective and versatile alternative to thermal annealing to equilibrate and control the assembly of polymer chains in thin films. Here, we present scientific and practical aspects of the solvent vapor annealing method, including the discussion of such factors as non-equilibrium conformational states and chain dynamics in thin films in the presence of solvent. Homopolymer and block copolymer films have been used in model studies to evaluate the robustness and the reproducibility of the solvent vapor processing, as well as to assess polymer-solvent interactions under confinement. Advantages of utilizing a well-controlled solvent vapor environment, including practically interesting regimes of weakly saturated vapor leading to poorly swollen states, are discussed. Special focus is given to dual temperature control over the set-up instrumentation and to the potential of solvo-thermal annealing. The evaluated insights into annealing dynamics derived from the studies on block copolymer films can be applied to improve the processing of thin films of crystalline and conjugated polymers as well as polymer composite in confined geometries.
KW  - solvent vapor annealing
KW  - block copolymer films
KW  - ellipsometry
KW  - guided self assembly
Y1  - 2019
U6  - https://doi.org/10.3390/polym11081312
SN  - 2073-4360
VL  - 11
IS  - 8
PB  - MDPI
CY  - Basel
ER  - 
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  -