Abstract
Polymer films with holes or fractal-like structures whose size is on the micron scale are of great interest. In this study, fractal-like structures of insoluble polythiophene were prepared via CS2 vapor annealing of solid thermocleavable polythiophene films in the presence of high humidity and subsequent thermal curing. Atomic force microscope and transmission electron microscopy observations demonstrate that holes form during the initial stage of solvent vapor annealing (SVA), further developing into fractal-like structures with the coalescence of the individual holes. Meanwhile, the crystallinity of the films can also be improved. A mechanism that involves solvent-covered water droplets has been proposed to explain the formation of the holes and the fractal-like structures. This is the first report of the formation of holes and fractal-like structures from solid films of conjugated polymers via SVA. The fractal-like structures can be preserved during the conversion from thermocleavable polythiophene to insoluble polythiophene by thermal curing.
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References
Albert, J. N. L., Young, W.-S., Lewis, R. L., Bogart, T. D., Smith, J. R. & Epps, T. H. Systematic study on the effect of solvent removal rate on the morphology of solvent vapor annealed ABA triblock copolymer thin films. ACS Nano. 6, 459–466 (2012).
Tang, H., Lu, G., Li, L., Li, J., Wang, Y. & Yang, X. Precise construction of PCBM aggregates for polymer solar cells via multi-step controlled solvent vapor annealing. J. Mater. Chem. 20, 683–688 (2010).
Bikel, M., Punt, I. G. M., Lammertink, R. G. H. & Wessling, M. Micropatterned polymer films by vapor-induced phase separation using permeable molds. ACS Appl. Mater. Interfaces 1, 2856–2861 (2009).
Bull, T. A., Pingree, L. S. C., Jenekhe, S. A., Ginger, D. S. & Luscombe, C. K. The role of mesoscopic PCBM crystallites in solvent vapor annealed copolymer solar cells. ACS Nano 3, 627–636 (2009).
Yeo, J.-S., Yun, J.-M., Kim, D.-Y., Park, S., Kim, S.-S., Yoon, M.-H., Kim, T.-W. & Na, S.-I. Significant vertical phase separation in solvent-vapor-annealed Poly(3,4-ethylenedioxythiophene):Poly(styrene sulfonate) composite films leading to better conductivity and work function for high-performance indium tin oxide-free optoelectronics. ACS Appl. Mater. Interfaces 4, 2551–2560 (2012).
Miller, S., Fanchini, G., Lin, Y.-Y., Li, C., Chen, C.-W., Su, W.-F. & Chhowalla, M. Investigation of nanoscale morphological changes in organic photovoltaics during solvent vapor annealing. J. Mater. Chem. 18, 306–312 (2008).
Xiao, X., Hu, Z., Wang, Z. & He, T. Study on the single crystals of Poly(3-octylthiophene) induced by solvent-vapor annealing. J. Phys. Chem. B 113, 14604–14610 (2009).
Lu, G. H., Li, L. G. & Yang, X. N. Achieving perpendicular alignment of rigid polythiophene backbones to the substrate by using solvent-vapor treatment. Adv. Mater. 19, 3594–3598 (2007).
Xiao, X., Wang, Z., Hu, Z. & He, T. Single crystals of polythiophene with different molecular conformations obtained by tetrahydrofuran vapor annealing and controlling solvent evaporation. J. Phys. Chem. B 114, 7452–7460 (2010).
Kim, D. H., Park, Y. D., Jang, Y., Kim, S. & Cho, K. Solvent vapor-induced nanowire formation in poly(3-hexylthiophene) thin films. Macromol. Rapid Commun. 26, 834–839 (2005).
Stoykovich, M. P., Muller, M., Kim, S. O., Solak, H. H., Edwards, E. W., de Pablo, J. J. & Nealey, P. F. Directed assembly of block copolymer blends into nonregular device-oriented structures. Science 308, 1442–1446 (2005).
Bosworth, J. K., Paik, M. Y., Ruiz, R., Schwartz, E. L., Huang, J. Q., Ko, A. W., Smilgies, D.-M., Black, C. T. & Ober, C. K. Control of self-assembly of lithographically patternable block copolymer films. ACS Nano 2, 1396–1402 (2008).
Albert, J. N. L., Bogart, T. D., Lewis, R. L., Beers, K. L., Fasolka, M. J., Hutchison, J. B., Vogt, B. D. & Epps, T. H. Gradient solvent vapor annealing of block copolymer thin films using a microfluidic mixing device. Nano Lett. 11, 1351–1357 (2011).
Bang, J., Kim, B. J., Stein, G. E., Russell, T. P., Li, X., Wang, J., Kramer, E. J. & Hawker, C. J. Effect of humidity on the ordering of PEO-based copolymer thin films. Macromolecules 40, 7019–7025 (2007).
Peng, J., Xuan, Y., Wang, H. F., Li, B. Y. & Han, Y. C. Solvent vapor induced dewetting in diblock copolymer thin films. Polymer (Guildf) 46, 5767–5772 (2005).
Liu, J. S., Kadnikova, E. N., Liu, Y. X., McGehee, M. D. & Frechet, J. M. J. Polythiophene containing thermally removable solubilizing groups enhances the interface and the performance of polymer-titania hybrid solar cells. J. Am. Chem. Soc. 126, 9486–9487 (2004).
Bjerring, M., Nielsen, J. S., Nielsen, N. C. & Krebs, F. C. Polythiophene by solution processing. Macromolecules 40, 6012–6013 (2007).
Prosa, T. J., Winokur, M. J. & McCullough, R. D. Evidence of a novel side chain structure in regioregular poly(3-alkylthiophenes). Macromolecules 29, 3654–3656 (1996).
Di, Z., Posselt, D., Smilgies, D.-M. & Papadakis, C. M. Structural rearrangements in a lamellar diblock copolymer thin film during treatment with saturated solvent vapor. Macromolecules 43, 418–427 (2010).
Sun, Y., Henderson, K. J., Jiang, Z., Strzalka, J. W., Wang, J. & Shull, K. R. Effects of reactive annealing on the structure of Poly(methacrylic acid)-Poly(methyl methacrylate) diblock copolymer thin films. Macromolecules 44, 6525–6531 (2011).
Bunz, U. H. F. Breath figures as a dynamic templating method for polymers and nanomaterials. Adv. Mater. 18, 973–989 (2006).
Ma, C.-Y., Zhong, Y.-W., Li, J., Chen, C.-K., Gong, J.-L., Xie, S.-Y., Li, L. & Ma, Z. Patterned carbon nanotubes with adjustable array: a functional breath figure approach. Chem. Mater. 22, 2367–2374 (2010).
Wan, L.-S., Li, J.-W., Ke, B.-B. & Xu, Z.-K. Ordered microporous membranes templated by breath figures for size-selective separation. J. Am. Chem. Soc. 134, 95–98 (2012).
Jeromenok, J., Boehlmann, W., Antonietti, M. & Weber, J. Intrinsically microporous polyesters from betulin—toward renewable materials for gas separation made from birch bark. Macromol. Rapid Commun. 32, 1846–1851 (2011).
Li, X., Wang, Y., Zhang, L., Tan, S., Yu, X., Zhao, N., Chen, G. & Xu, J. Fabrication of honeycomb-patterned polyalkylcyanoacrylate films from monomer solution by breath figures method. J. Colloid Interface Sci. 350, 253–259 (2010).
Johansson, E. M. J., Pradhan, S., Wang, E., Unger, E. L., Hagfeldt, A. & Andersson, M. R. Efficient infiltration of low molecular weight polymer in nanoporous TiO2. Chem. Phys. Lett. 502, 225–230 (2011).
Fredin, K., Johansson, E. M. J., Hahlin, M., Scholin, R., Plogmaker, S., Gabrielsson, E., Sun, L. & Rensmo, H. Solid state dye-sensitized solar cells prepared by infiltrating a molten hole conductor into a mesoporous film at a temperature below 150 degrees C. Synth. Met. 161, 2280–2283 (2011).
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This work was financially supported by the ‘Hundred Talents Program’ of the Chinese Academy of Sciences, National Natural Science Foundation of China (21274158, 51173020).
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Sun, J., Wu, G. & Geng, J. Preparation of fractal-like structures of insoluble polythiophene via solvent vapor annealing of solid thermocleavable polythiophene films and subsequent thermal curing. Polym J 45, 813–818 (2013). https://doi.org/10.1038/pj.2012.224
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DOI: https://doi.org/10.1038/pj.2012.224
