TY  - JOUR
A1  - Brosnan, Sarah M.
A1  - Schlaad, Helmut
A1  - Antonietti, Markus
T1  - Aqueous Self-Assembly of Purely Hydrophilic Block Copolymers into Giant Vesicles
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
N2  - Self-assembly of macromolecules is fundamental to life itself, and historically, these systems have been primitively mimicked by the development of amphiphilic systems, driven by the hydrophobic effect. Herein, we demonstrate that self-assembly of purely hydrophilic systems can be readily achieved with similar ease and success. We have synthesized double hydrophilic block copolymers from polysaccharides and poly(ethylene oxide) or poly(sarcosine) to yield high molar mass diblock copolymers through oxime chemistry. These hydrophilic materials can easily assemble into nanosized (<500nm) and microsized (>5m) polymeric vesicles depending on concentration and diblock composition. Because of the solely hydrophilic nature of these materials, we expect them to be extraordinarily water permeable systems that would be well suited for use as cellular mimics.
KW  - block copolymers
KW  - polymersomes
KW  - polysaccharides
KW  - self-assembly
KW  - vesicles
Y1  - 2015
U6  - https://doi.org/10.1002/anie.201502100
SN  - 1433-7851
SN  - 1521-3773
VL  - 54
IS  - 33
SP  - 9715
EP  - 9718
PB  - Wiley-VCH
CY  - Weinheim
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  -