Caracterização óptica e morfológica de filmes automontados de POMA/PPV

by de Campos, Karyne Ramos

Abstract (Summary)
This work presents the optical and morphological characterization of layer-by-layer(LBL) ultra-thin films from poly(p-phenylene vinylene) (PPV) and poly(o-methoxyaniline)(POMA). The PPV films were processed using the precursor polymer poly(xylylidenetetrahydrothiophenium chloride) (PTHT) and the sodium dodecylbenzenesulfonate (DBS). Thefilms were deposited on glass substrate (BK7) with 2, 5, and 10 layers of POMA in esmeraldinesalt form and 5, 10, 25 and 50 layers of PTHT+DBS. The PPV+DBS films on POMA layer wereobtained from the thermal conversion process at 110oC and 230 oC under vacuum (10-2 atm)environment during 2 h. The optical characterizations were performed with absorbance,photoluminescence as function of the sample temperature, selective excitation, polarizedabsorbance and photoluminescence. The Raman spectroscopy and Atomic Force Microscopy(AFM) characterization were performed to study the structural and surface morphologicalproperties, respectively, of LbL POMA/PPV films. The absorption experiment shows that thePPV+DBS layers are adsorbed in same ratio, independently, on the number of POMA layers andthe thermal conversion temperature. The line shape of the photoluminescence (PL) is not affectedwith the PPV conversion reaction for all samples on POMA layer. High thermal stability of PPVwas observed; witch the integrated PL decreasing only 10% when the temperature was increasedfrom 10 to 300K. On the other hand, the PL spectra for LbL with 25 layers of PPV+DBSdeposited on glass substrate decrease 80% in the same sample temperature range. The line shapeof selective excitation spectra is similar of the absorbance one for LBL POMA/PPV films. Themolecular order analyses through of the polarized absorbance and PL show that the POMA andPPV molecules are, preferential, oriented in the dip direction. This result was confirmed via AFManalysis. From Raman data, it was possible to identify the polymer/polymer interface region andthe molecular group?s interaction between POMA and PPV. Finally, a physical model wasproposal based on experimental data to explain the optical properties of PPV on POMA layer.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Tome Mauro Schmidt; Ivan Helmuth Bechtold; Alexandre Marletta

School:Universidade Federal de Uberlândia

School Location:Brazil

Source Type:Master's Thesis

Keywords:Técnica layer by Layer-by-layer technique Poly(o-methoxyaniline) Poly(p-phenylene vinylene) Optical and morphological characterization


Date of Publication:02/25/2008

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