Large-Scale Simultaneous Orientation of CdSe Nanorods and Regioregular Poly(3-hexylthiophene) by Mechanical Rubbing

• Published in: Macromolecules Vol. 46; no. 15; pp. 6177 - 6186
• Main Authors: Hartmann, Lucia, Djurado, David, Florea, Ileana, Legrand, Jean-François, Fiore, Angela, Reiss, Peter, Doyle, Stephen, Vorobiev, Alexeï, Pouget, Stéphanie, Chandezon, Frédéric, Ersen, Ovidiu, Brinkmann, Martin
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13.08.2013
• Subjects: Applied sciences; Chemical Sciences; Composites; Exact sciences and technology; Forms of application and semi-finished materials; Polymer industry, paints, wood; Polymers; Technology of polymers; Mixing; Aromatic polymer; Head to tail polymer; Experimental study; Thin film; Cadmium selenides; Conjugated polymer; Molecular orientation; Oriented polymer; Friction; Thiophene derivative polymer; Morphology; Concentration effect; Nanocomposite; Manufacturing; Nanorod; Growth from solution; Particle orientation
• DOI: 10.1021/ma400880x
• ISSN: 0024-9297

Highly oriented hybrid thin films composed of rod-shaped CdSe nanocrystals and poly(3-hexylthiophene) are prepared by mechanical rubbing. The orientation distribution of both CdSe nanorods and crystalline P3HT domains is determined by a combination of transmission electron microscopy (electron diffraction, low dose high-resolution TEM, and tomography), grazing incidence X-ray diffraction measurements, and UV–vis spectroscopy. After rubbing, P3HT crystalline domains show a preferential face-on orientation ((010) contact plane) and the chains align parallel to the rubbing direction. CdSe nanorods also align parallel to the rubbing direction, but the level of alignment is a function of their concentration in the polymer matrix: the lower their concentration, the higher the level of in-plane orientation of both the nanorods and the polymer chains. GIXD and electron diffraction suggest that CdSe nanorods adopt a preferential contact plane on the substrate after rubbing. The high in-plane alignment of the nanorods is mainly due to the orientation of the surrounding P3HT matrix. In particular, low dose HR-TEM shows that the local orientation of individual NRs matches the orientation of the surrounding π-stacked P3HT chains. For a high NR concentration, bundling of NRs into larger aggregates prevents their efficient alignment by rubbing.