Full text
| |
| Author(s): |
Rafaela Cristina Sanfelice
Total Authors: 1
|
| Document type: | Doctoral Thesis |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD) |
| Defense date: | 2014-09-10 |
| Examining board members: |
Débora Terezia Balogh;
Sergio Paulo Campana Filho;
Marystela Ferreira;
Osvaldo Novais de Oliveira Junior;
Antonio Riul Júnior
|
| Advisor: | Débora Terezia Balogh |
| Abstract | |
The main aim of this doctorate work was the preparation of hybrid materials formed from the union of gold nanoparticles with the polymer poly (3-hexylthiophene) (P3HT). The hybrid material was obtained through the production of Langmuir and Langmuir-Schaefer (LS) films. Gold nanoparticles were synthesized in aqueous phase (AuNp) using the Turkvich method and encapsulated with 1-Octadecanethiol (AuNpOctathiol) with solubility in chloroform. The AuNp were used in the subphase of a Langmuir trough and the P3HT was spread at the air/water interface. When the Langmuir film was transferred, forming the Langmuir-Schaefer films (horizontal deposition), it was possible to get a hybrid material containing AuNp and P3HT. The AuNpOctathiol were used for the preparation of hybrid LS films through the spreading of a solution containing a mixture of P3HT and AuNpOctathiol with different proportions. The presence of gold nanoparticles has been demonstrated mainly by FEG-SEM images. The LS films of P3HT showed optical anisotropy, allowing to infer the type of orientation of the molecules in both Langmuir and LS films. The incorporation of gold nanoparticle in the film influenced the orientation of P3HT, as well as the process of photodegradation of LS films. These films were used in sensitivity tests for vapor of volatile organic compounds and water through measurements of visible light. The films showed sensitivity only for three of the tested compounds: toluene, THF and chloroform. P3HT films exhibited electrochromic behavior and this effect can be observed by applying potential through cyclic voltammetry during the registration of the absorption in the visible spectrum of the film. A similar Electrochromic behavior was observed in all LS films, showing reversibility of the initial color only with the passage of the reverse potential, or after a certain time. Such behavior was not observed in Spin-coating films, which showed recovery of the color immediately after stopping the potential. This fact indicates not only that greater order of LS films maintains the film doping, but also the presence of gold nanoparticles does not change this property. (AU) | |
| FAPESP's process: | 10/11040-5 - Metal nanoparticles incorporation on conjugated polymers: preparation, characterization and fabrication of nanostructured films |
| Grantee: | Rafaela Cristina Sanfelice |
| Support Opportunities: | Scholarships in Brazil - Doctorate |