TY  - JOUR
A1  - Schuh, Christian
A1  - Lomadze, Nino
A1  - Rühe, Jürgen
A1  - Kopyshev, Alexey
A1  - Santer, Svetlana
T1  - Photomechanical degrafting of Azo-functionalized Poly(methacrylic acid) (PMAA) brushes
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - We report on the preparation and characterization of photosensitive polymer brushes. The brushes are synthesized through polymer analogous attachment of azobenzene groups to surface-attached poly(methacrylic acid) (PMAA) chains. The topography of the photosensitive brushes shows a strong reaction upon irradiation with UV light. While homogeneous illumination leaves the polymer topography unchanged, irradiation of the samples with interference patterns with periodically varying light intensity leads to the formation of surface relief gratings (SRG). The height of the stripes of the grating can be controlled by adjusting the irradiation time. The SRG pattern can be erased through solvent treatment when the periodicity of the stripe pattern is less than the length of the fully stretched polymer chains. In the opposite case, photomechanical scission of receding polymer chains is observed during SRG formation, and the inscribed patterns are permanent.
Y1  - 2011
U6  - https://doi.org/10.1021/jp2041229
SN  - 1520-6106
VL  - 115
IS  - 35
SP  - 10431
EP  - 10438
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Lomadze, Nino
A1  - Kopyshev, Alexey
A1  - Rühe, Jürgen
A1  - Santer, Svetlana
T1  - Light-Induced chain scission in photosensitive polymer brushes
JF  - Macromolecules : a publication of the American Chemical Society
N2  - We report on a process inducing photomechanical fracture of chemical bonds in photosensitive PMAA polymer brushes. The photosensitive PMAA polymer brushes were prepared by covalent attachment of azobenzene groups to poly(methylacrylic acid) (PMAA) chains generated by surface-initiated polymerization. While homogeneous irradiation leaves the polymer topography unchanged, the azo-PMAA brushes show a strong response upon irradiation with UV interference patterns. The photoisomerization process in the surface-attached polymer films results in the irreversible formation of surface relief gratings (SRG), which are strongly enhanced upon washing with a good solvent for the polymer. The photomechanical forces during mass transport induced by the irradiation lead to the scission of covalent bounds and accordingly to a degrafting of the polymer chains in areas where the polymer is receding from. It is observed that the number of ruptured chains depends strongly on the amount of azo side chains in the polymer.
Y1  - 2011
U6  - https://doi.org/10.1021/ma201016q
SN  - 0024-9297
VL  - 44
IS  - 18
SP  - 7372
EP  - 7377
PB  - American Chemical Society
CY  - Washington
ER  -