| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 102 === In this thesis, we reported the preparation, the microstructures and the optical properties of poly(3-hexylthiophene)/TiO2 nanocomposites based on aldehyde end-functionalized P3HT (P3HT-CHO) and amphiphilic P3HT block copolymer, poly(3-hexylthiophene-block-hydroxylated isoprene) (P3HT-b-PIOH). Pristine unmodified P3HT were also used for reference studies. Two methods were employed to prepare the Nanocomposites: (1) solution blending of polymers and commercial available TiO2 nanoparticles, Degussa P25 (~21 nm); (2) in-situ sol gel process of TiO2 precursors in polymer solution.
The attractive interaction between aldehyde of P3HT-CHO and hydroxyl group of TiO2 allowed smaller aggregations of TiO2 (~ 50 - 200 nm) blending.The in-situ sol gel processes using chlorotitanium triisopropoxide (ClTIP) would further enhance the homogeneity in TiO2 dispersion despite of enlarged particle sizes (~ 50 -200 nm) as the aldehyde group of P3HT-CHO would react with ClTIP to form covalent bonds to anchor P3HT in the surface of TiO2. Thus preventing the aggregation of TiO2. Since the in-situ sol gel process avoid the use of dispersants and ligands of TiO2 nanoparticles, the photoluminescence quenching of P3HT-CHO/ClTIP composites could be further improved comparing to P3HT-CHO/P25.
The use of amphiphilic P3HT-b-PIOH block copolymer remarkably afforded the resulting P3HT-b-PIOH/ClTIP composites having uniformed TiO2 nanoparticles (~ 30 nm) homogenously dispersed in the polymer matrix, which could be attributed the increasing number of covalent linkages between the hydroxyl groups of PIOH and ClTIP.
The optical properties were derived from the UV-vis spectroscopy. Even the loading of TiO2 was up to 30 wt%, the maximum absorption peak was not blue-shifted and the π-π stacking of P3HT retain for P3HT-CHO/ClTIP and P3HT-b-PIOH/ClTIP composites
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