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http://ciqa.repositorioinstitucional.mx/jspui/handle/1025/561| Chemical and microwave-assist functionalization of graphene oxide with rigid rod-like poly(phenylene ethynylene)s. Photophysical, molecular and structural analysis | |
| GLEB TURLAKOV | |
| Acceso Abierto | |
| Atribución-NoComercial-SinDerivadas | |
| Doctorado en tecnología de polímeros | |
| In the present work, the influence of functional group incorporation on the GO surface was
studied. Several approaches were applied with the aim to increase GO layers spacing and
functionalize them for further application. Polymer grafting was performed via
esterification reaction between the carboxylic group of GO and the OH terminal group of
the polymer. Nanohybrid materials comprising graphene oxide and a series of conjugated
copolymers with different electron-donating and withdrawing groups were synthesized by
microwave irradiation, which represents a green, effective and rapid heating method. The
microwave irradiation matches perfectly with graphene oxide structure decorated with high
polar functional groups which allowed the esterification. Polymers, as well as composites,
were characterized by optical spectroscopy, Raman spectroscopy, cyclic voltammetry (CV),
X-rays diffraction (XRD), X-Ray photoemission spectroscopy (XPS) and transmission
electron microscopy (TEM). Effective interactions among the polymer functional group
and graphene oxide, likely due to π–π stacking, are confirmed by fluorescence quantum
yield (Φ), radiative rate constant (kr), fluorescence lifetime (τ), and non-radiative rate (k
nr)constants. The introduction of graphene oxide allows for the reduction of the band gap of
the active layer in optoelectronic devices. These results were corroborated by CV and UVVis
spectroscopy. Graphene oxide exhibits a strong quenching effect revealed by
fluorescence spectroscopy and time resolved spectroscopy. All spectroscopy data
underscore the electronic coupling between polymers and graphene oxide in the
nanohybrids. The self-assembly properties of several functionalized poly(p-phenyleneethynylene)s (PPEs) copolymers, oligomers, commercial polymers and small molecules on HOPG were investigated by using scanning tunneling microscopy (STM) at the solid/air and solid/liquid interface. The results show the ability of such polymers to self-assemble into nanowire-like structures on the HOPG surface. The self-assembly of PPE systems is thought to result from the different types of non-covalent bonding, such as π-π interactions and hydrogen bonds particularly between the adjacent alkoxy groups attached to the polymer backbone. Other types of weaker interactions such as pi-hydrogen bonding and van der Walls forces may also contribute to the final configuration of the self-assembled PPE-HOPG structure. Scanning tunneling microscopy (STM) and X-ray analyses were used to study the selfassembly of a series of four copolymers on HOPG. STM was also used to study the wellknown Moiré pattern of HOPG (the phenomena characterizing the mismatch of graphene layers of HOPG) and to distinguish the triangular and honeycomb lattice structures seen for HOPG and the observation of strands in the STM images. | |
| 2018 | |
| Tesis de doctorado | |
| QUÍMICA | |
| Aparece en las colecciones: | Tesis de Doctorado |
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| Fichero | Tamaño | Formato | |
|---|---|---|---|
| TESIS DTP Gleb Turlakov 4 sep 2017.pdf | 6.14 MB | Adobe PDF | Visualizar/Abrir |