TY  - JOUR
A1  - Kopyshev, Alexey
A1  - Kanevche, Katerina
A1  - Lomadze, Nino
A1  - Pfitzner, Emanuel
A1  - Loebner, Sarah
A1  - Patil, Rohan R.
A1  - Genzer, Jan
A1  - Heberle, Joachim
A1  - Santer, Svetlana
T1  - Light-Induced Structuring of Photosensitive Polymer Brushes
JF  - ACS Applied polymer materials
N2  - We investigate light-induced irreversible structuring of surface topographies in poly(3-sulfopropyl methacrylate/potassium salt) (PSPMK) brushes on flat solid substrates prepared by surface-initiated atom transfer radical polymerization. The brushes have been loaded with azobenzene-based surfactant comprised of positively charged headgroups and hydrophobic tail. The surfactant exhibits photoresponsive properties through photoisomerization from the trans to cis states leading to significant changes in physicochemical properties of grafted polymer chains. The azobenzene surfactant enables photoresponsive behavior without introducing irreversible changes to chemical composition of the parent polymer brush. Exposing these photosensitive brushes to irradiation with UV interference beams causes the polymer brush to form surface relief grating (SRG) patterns. The cationic surfactant penetrates only similar to 25% of the upper portion of the PSPMK brush, resulting in the formation of two sections within the brush: a photoresponsive upper layer and nonfunctional buried layer, which is not affected by the UV irradiation. Using nano-FTIR spectroscopy, we characterize locally the chemical composition of the polymer brush and confirm partial penetration of the surfactant within the film. Strong optomechanical stresses take place only within the upper layer of the brush that is impregnated with the surfactants and causes surface topography alternation due to a local rupture of grafted polymer chains. The cleaved polymer chains are then removed from the surface by using a good solvent, leaving behind topographical grating on top of the nonfunctional brush layer. We demonstrate that photostructured polymer brush can be used for reversible switching of brush topography by varying external humidity.
KW  - photosensitive polymer brushes
KW  - reversible and irreversible structuring of polymer brushes
KW  - photosensitive azobenzene containing surfactant
KW  - strong polyelectrolyte brush
KW  - SRG formation in polymer brushes
Y1  - 2019
U6  - https://doi.org/10.1021/acsapm.9b00705
SN  - 2637-6105
VL  - 1
IS  - 11
SP  - 301
EP  - 3026
PB  - American Chemical Society
CY  - Washington
ER  -