Development of rGO/PANI/PVA-Based Electrospun Nanocomposites
Materials Science and Engineering, MSc. Thesis, 2015
Assosc. Prof. Dr. Selmiye Alkan Gürsel (Thesis Advisor),
Assist. Prof. Dr. Fevzi Çakmak Cebebi (Thesis Co-advisor),,
Assoc. Prof. Dr. Melih Papila (Thesis Co-advisor),
Assosc. Prof. Dr. Burç Mısırlıoğlu,
Assist. Prof. Dr. Elif Özden Yenigün
Date & Time: 28th, 2015 – 10:00 AM
Keywords : Graphene, Electrospinning, Nanocomposite, Colloidal Suspension
In this project, with the scope electromechanically responsive nanocomposite applications, fibrous nanocomposites with various filler compositions based on poly(vinyl alcohol) (PVA) as the polymer matrix, reduced graphene oxide (rGO), and polyaniline (PANI) as conductive reinforcing filler components were successfully prepared via electrospinning and their relative properties were systematically investigated.
Prior to electrospinning suspension preparation, graphene oxide (GO) was prepared from natural graphite flakes through an improved method based on Hummer’s Modified conventional method. Subsequently, high temperature thermal treatment on the as-prepared GO resulted in formation of thermally reduced GO. Additionally, PANI nanofibers were synthesized via chemical oxidation polymerization starting from aniline monomer.
After optimization of PVA concentration in electrospinning media, two main nanofiber preparation and characterization steps were designed and conducted according to the following procedures.
Firstly, incorporation of reduced graphene oxide of certain amounts in the electrospinning media was performed by means of co-solvent assisted suspension preparation method proposed by our group followed by electrospinning of respective solutions. Rheological behavior of electrospinning suspensions in addition to morphological, mechanical and thermal properties of their respective as-spin mats was investigated.
Secondly, PANI as the electroactive polymer was introduced to the electrospinning suspension recipe optimized during the previous step. In order to improve electrical conductivity of mentioned tri-component PVA/rGO/ PANI as-spun mats, two different post-spinning treatment approaches were performed.
The first modification applied included cross-linking of electrospun thin mats using the glutaraldehyde solution, followed by doping of emeraldine base PANI inside the structure, during which, further transformation of PANI state to conductive emeraldine salt was achieved and confirmed by Fourier-Transformed IR spectroscopy (FT-IR).
The second modification approach used was thermal treatment through a neutral gas-condition annealing process. The main goal to pursue this method was to both partially eliminate the insulating PVA matrix as well as thermal doping of PANI.
While the as-spun showed no response to applied voltages and performed as insulating layers, the post-treated samples showed relatively improved electrical properties and the highest electrical conductivity was peaked at over 19µS.cm-1.