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Liu JX, Xia Y, Wang Y, Haataja MP, Arnold CB, Priestley RD. Anisotropic material depletion in epitaxial polymer crystallization. SOFT MATTER 2023; 19:7691-7695. [PMID: 37811707 DOI: 10.1039/d3sm00758h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
The physical properties of a semicrystalline polymer thin film are intimately related to the morphology of its crystalline domains. While the mechanisms underlying crystallization of flat-on oriented polymer crystals are well known, similar mechanisms remain elusive for edge-on oriented thin films due to the propensity of substantially thin films to adopt flat-on orientations. Here, we employ an epitaxial polymer-substrate relationship to enforce edge-on crystallization in thin films. Using matrix-assisted pulsed laser evaporation (MAPLE), we deposit films in which crystal nucleation is spatially separated from subsequent epitaxial crystallization. These experiments, together with phase-field simulations, demonstrate a highly anisotropic and localized material depletion during edge-on crystallization. These results provide deeper insight into the physics of polymer crystallization under confinement and introduce a processing motif in the crystallization of ultrathin structured films.
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Affiliation(s)
- Jason X Liu
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA
- Princeton Materials Institute, Princeton University, Princeton, NJ 08544, USA.
| | - Yang Xia
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Yucheng Wang
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Mikko P Haataja
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA
- Princeton Materials Institute, Princeton University, Princeton, NJ 08544, USA.
| | - Craig B Arnold
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA
- Princeton Materials Institute, Princeton University, Princeton, NJ 08544, USA.
| | - Rodney D Priestley
- Princeton Materials Institute, Princeton University, Princeton, NJ 08544, USA.
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
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Baranov MA, Klimchitskaya GL, Mostepanenko VM, Velichko EN. Fluctuation-induced free energy of thin peptide films. Phys Rev E 2019; 99:022410. [PMID: 30934220 DOI: 10.1103/physreve.99.022410] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Indexed: 01/11/2023]
Abstract
We apply the Lifshitz theory of dispersion forces to find a contribution to the free energy of peptide films that is caused by the zero-point and thermal fluctuations of the electromagnetic field. For this purpose, using available information about the imaginary parts of the dielectric permittivity of peptides, an analytic representation for permittivity of a typical peptide along the imaginary frequency axis is devised. Numerical computations of the fluctuation-induced free energy are performed at room temperature for freestanding peptide films containing different fractions of water, and for similar films deposited on dielectric (SiO_{2}) and metallic (Au) substrates. It is shown that the free energy of a freestanding peptide film is negative and thus contributes to its stability. The magnitude of the free energy increases with increasing fraction of water and decreases with increasing thickness of a film. For peptide films deposited on a dielectric substrate, the free energy is nonmonotonous. It is negative for films thicker than 100nm, reaches the maximum value at some film thickness, but vanishes and changes its sign for films thinner than 100nm. The fluctuation-induced free energy of peptide films deposited on metallic substrate is found to be positive, which makes films less stable. In all three cases, simple analytic expressions for the free energy of sufficiently thick films are found. The obtained results may be useful to attain film stability in the next generation of organic microdevices with further reduced dimensions.
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Affiliation(s)
- M A Baranov
- Institute of Physics, Nanotechnology and Telecommunications, Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg 195251, Russia
| | - G L Klimchitskaya
- Institute of Physics, Nanotechnology and Telecommunications, Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg 195251, Russia.,Central Astronomical Observatory at Pulkovo of the Russian Academy of Sciences, Saint Petersburg 196140, Russia
| | - V M Mostepanenko
- Institute of Physics, Nanotechnology and Telecommunications, Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg 195251, Russia.,Central Astronomical Observatory at Pulkovo of the Russian Academy of Sciences, Saint Petersburg 196140, Russia.,Kazan Federal University, Kazan 420008, Russia
| | - E N Velichko
- Institute of Physics, Nanotechnology and Telecommunications, Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg 195251, Russia
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Fang A, Haataja M. Simulation study of twisted crystal growth in organic thin films. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:042404. [PMID: 26565254 DOI: 10.1103/physreve.92.042404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Indexed: 06/05/2023]
Abstract
Many polymer and organic small-molecule thin films crystallize with microstructures that twist or curve in a regular manner as crystal growth proceeds. Here we present a phase-field model that energetically favors twisting of the three-dimensional crystalline orientation about and along particular axes, allowing morphologies such as banded spherulites, curved dendrites, and "s"- or "c"-shaped needle crystals to be simulated. When twisting about the fast-growing crystalline axis is energetically favored and spherulitic growth conditions are imposed, crystallization occurs in the form of banded spherulites composed of radially oriented twisted crystalline fibers. Due to the lack of symmetry, twisting along the normal growth direction leads to heterochiral banded spherulites with opposite twist handedness in each half of the spherulite. When twisting is instead favored about the axis perpendicular to the plane of the substrate and along the normal growth direction under diffusion-limited single-crystalline growth conditions, crystallization occurs in the form of curved dendrites with uniformly rotating branches. We show that the rate at which the branches curve affects not only the morphology but also the overall kinetics of crystallization, as the total crystallized area at a given time is maximized for a finite turning rate.
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Affiliation(s)
- Alta Fang
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Mikko Haataja
- Department of Mechanical and Aerospace Engineering, Princeton Institute for the Science and Technology of Materials (PRISM), the Andlinger Center for Energy and the Environment (ACEE), and Program in Applied and Computational Mathematics (PACM), Princeton University, Princeton, New Jersey 08544, USA
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Liu L, Zhang W, Guo P, Wang K, Wang J, Qian H, Kurash I, Wang CH, Yang YW, Xu F. A direct Fe–O coordination at the FePc/MoOx interface investigated by XPS and NEXAFS spectroscopies. Phys Chem Chem Phys 2015; 17:3463-9. [DOI: 10.1039/c4cp04199b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
FePc adsorption highly facilitates the thermal reduction of the MoO3 layer, of which the mechanism involves an additional direct coupling between FePc molecules and the MoOx substrate in addition to the formation of the oxygen vacancies.
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Affiliation(s)
- Lingyun Liu
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Wenhua Zhang
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Panpan Guo
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Kai Wang
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Jiaou Wang
- Beijing Synchrotron Radiation Laboratory
- Institute of High Energy Physics
- Chinese Academy of Sciences
- Beijing 100039
- P. R. China
| | - Haijie Qian
- Beijing Synchrotron Radiation Laboratory
- Institute of High Energy Physics
- Chinese Academy of Sciences
- Beijing 100039
- P. R. China
| | - Ibrahim Kurash
- Beijing Synchrotron Radiation Laboratory
- Institute of High Energy Physics
- Chinese Academy of Sciences
- Beijing 100039
- P. R. China
| | - Chia-Hsin Wang
- National Synchrotron Radiation Research Center
- Hsinchu
- Taiwan
| | - Yaw-Wen Yang
- National Synchrotron Radiation Research Center
- Hsinchu
- Taiwan
| | - Faqiang Xu
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- P. R. China
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