TY  - JOUR
A1  - Di Florio, G.
A1  - Bruendermann, E.
A1  - Yadavalli, Nataraja Sekhar
A1  - Santer, Svetlana
A1  - Havenith, Martina
T1  - Confocal raman microscopy and AFM study of the interface between the photosensitive polymer layer and multilayer graphene
JF  - Soft materials
N2  - In this paper we report on the interaction between photosensitive azobenzene-containing polymer films and on top adsorbed graphene multilayers. The photosensitive polymer film changes its topography under irradiation with light interference patterns according to their polarization distribution. The multilayer graphene follows the deformation of the polymer film and stretches accordingly. Using confocal Raman microspectroscopy we can detect the appearance of additional peaks in the Raman spectrum of the photosensitive polymer film upon irradiation indicating a molecular interaction at the interface between the graphene multilayer and the polymer matrix. Multi-component analysis of the specific Raman bands shows that the interaction involves the graphene rings and the aromatic rings of the azobenzenes causing the strong adhesion between the two materials.
KW  - Graphene
KW  - Multilayer graphene
KW  - Photosensitive polymer film
KW  - Confocal Raman microscopy
KW  - AFM
KW  - Surface Relief Grating
KW  - Interfacial molecular interaction
Y1  - 2014
U6  - https://doi.org/10.1080/1539445X.2014.945040
SN  - 1539-445X
SN  - 1539-4468
VL  - 12
SP  - S98
EP  - S105
PB  - Taylor & Francis Group
CY  - Philadelphia
ER  - 
TY  - JOUR
A1  - Di Florio, G.
A1  - Bruendermann, E.
A1  - Yadavalli, Nataraja Sekhar
A1  - Santer, Svetlana
A1  - Havenith, Martina
T1  - Graphene multilayer as nanosized optical strain gauge for polymer surface relief gratings
JF  - Nano letters : a journal dedicated to nanoscience and nanotechnology
N2  - In this paper, we show how graphene can be utilized as a nanoscopic probe in order to characterize local opto-mechanical forces generated within photosensitive azobenzene containing polymer films. Upon irradiation with light interference patterns, photosensitive films deform according to the spatial intensity variation, leading to the formation of periodic topographies such as surface relief gratings (SRG). The mechanical driving forces inscribing a pattern into the films are supposedly fairly large, because the deformation takes place without photofluidization; the polymer is in a glassy state throughout. However, until now there has been no attempt to characterize these forces by any means. The challenge here is that the forces vary locally on a nanometer scale. Here, we propose to use Raman analysis of the stretching of the graphene layer adsorbed on top of polymer film under deformation in order to probe the strength of the material transport spatially resolved. With the well-known mechanical properties of graphene, we can obtain lower bounds on the forces acting within the film. Upon the basis of our experimental results, we can deduce that the internal pressure in the film due to grating formation can exceed 1 GPa. The graphene-based nanoscopic gauge opens new possibilities to characterize opto-mechanical forces generated within photosensitive polymer films.
KW  - Surface relief grating
KW  - optomechanical forces
KW  - photosensitive polymer films
KW  - multilayer graphene deformation
KW  - confocal Raman microscopy
Y1  - 2014
U6  - https://doi.org/10.1021/nl502631s
SN  - 1530-6984
SN  - 1530-6992
VL  - 14
IS  - 10
SP  - 5754
EP  - 5760
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - DiFlorio, Giuseppe
A1  - Bründermann, Erik
A1  - Yadavall, Nataraja Sekhar
A1  - Santer, Svetlana
A1  - Havenith, Martina
T1  - Polarized 3D Raman and nanoscale near-field optical microscopy of optically inscribed surface relief gratings: chromophore orientation in azo-doped polymer films
N2  - We have used polarized confocal Raman microspectroscopy and scanning near-field optical microscopy with a resolution of 60 nm to characterize photoinscribed grating structures of azobenzene doped polymer films on a glass support. Polarized Raman microscopy allowed determining the reorientation of the chromophores as a function of the grating phase and penetration depth of the inscribing laser in three dimensions. We found periodic patterns, which are not restricted to the surface alone, but appear also well below the surface in the bulk of the material. Near-field optical microscopy with nanoscale resolution revealed lateral two-dimensional optical contrast, which is not observable by atomic force and Raman microscopy.
Y1  - 2014
UR  - http://pubs.rsc.org/en/content/articlepdf/2014/sm/c3sm51787j
U6  - https://doi.org/10.1039/c3sm51787j
SN  - 1744-683x
ER  -