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Jaksch S, Gutberlet T, Müller-Buschbaum P. Grazing-incidence scattering—status and perspectives in soft matter and biophysics. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.04.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Saini A, Wolff M. Macroscopic Alignment of Micellar Crystals with Magnetic Microshearing. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:3980-3986. [PMID: 30767539 DOI: 10.1021/acs.langmuir.8b03701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The effect of small quantities of a magnetic polymer nanocomposite (formed by surfactant Pluronic F127 @ Fe3O4 nanoparticles of 10 and 30 nm diameters) on the crystallization behavior of Pluronic F127 micelles solvated by 20% in water was investigated in the vicinity of hydrophilic and hydrophobic interfaces. Introducing magnetic nanoparticle at the core imparts magnetic properties to the polymeric micelle and increases its hydrodynamic diameter. These magnetic polymer nanocomposites act as defects in the pluronic crystal and hinder crystallization in comparison to pure Pluronic F127 micelles' behavior. The magnetic field results in a motion of the magnetic micelles and a microshearing effect. This microshearing assists in self-organization of the crystal. Addition of magnetic micelles formed using 30 nm magnetite particles shows similar crystallization behavior, however, with an overall reduced crystallinity due to their significantly larger size compared to the lattice parameter and the dimension of the interstitial cavity for an fcc structure.
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Affiliation(s)
- Apurve Saini
- Department of Physics and Astronomy , Uppsala University , Uppsala 75120 , Sweden
| | - Max Wolff
- Department of Physics and Astronomy , Uppsala University , Uppsala 75120 , Sweden
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Wolff M, Saini A, Simonne D, Adlmann F, Nelson A. Time Resolved Polarised Grazing Incidence Neutron Scattering from Composite Materials. Polymers (Basel) 2019; 11:polym11030445. [PMID: 30960429 PMCID: PMC6473511 DOI: 10.3390/polym11030445] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 02/27/2019] [Accepted: 03/04/2019] [Indexed: 11/30/2022] Open
Abstract
Neutron scattering experiments are a unique tool in material science due to their sensitivity to light elements and magnetic induction. However, for kinetic studies the low brilliance at existing sources poses challenges. In the case of periodic excitations these challenges can be overcome by binning the scattering signal according to the excitation state of the sample. To advance into this direction we have performed polarised and time resolved grazing incidence neutron scattering measurements on an aqueous solution of the polymer F127 mixed with magnetic nano-particles. Magnetic nano-composites like this provide magnetically tuneable properties of the polymer crystal as well as magnetic meta-crystals. Even though the grazing incidence small angle scattering and polarised signals are too weak to be evaluated at this stage we demonstrate that such experiments are feasible. Moreover, we show that the intensity of the 111 Bragg peak of the fcc micellar crystal depends on the actual shear rate, with the signal being maximised when the shear rate is lowest (and vice-versa).
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Affiliation(s)
- Maximilian Wolff
- Department for Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, 752 37 Uppsala, Sweden.
| | - Apurve Saini
- Department for Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, 752 37 Uppsala, Sweden.
| | - David Simonne
- Department for Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, 752 37 Uppsala, Sweden.
| | - Franz Adlmann
- Department for Physics and Astronomy, Uppsala University, Lägerhyddsvägen 1, 752 37 Uppsala, Sweden.
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Gutfreund P, Maccarini M, Dennison AJC, Wolff M. The Search for Nanobubbles by Using Specular and Off-Specular Neutron Reflectometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:9091-9096. [PMID: 27516185 DOI: 10.1021/acs.langmuir.6b02087] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We apply specular and off-specular neutron reflection at the hydrophobic silicon/water interface to check for evidence of nanoscopic air bubbles whose presence is claimed after an ad hoc procedure of solvent exchange. Nanobubbles and/or a depletion layer at the hydrophobic/water interface have long been discussed and generated a plethora of controversial scientific results. By combining neutron reflectometry (NR), off-specular reflectometry (OSS), and grazing incidence small angle neutron scattering (GISANS), we studied the interface between hydrophobized silicon and heavy water before and after saturation with nitrogen gas. Our specular reflectometry results can be interpreted by assuming a submolecular sized depletion layer and the off-specular measurements show no change with nitrogen super saturated water. This picture is consistent with the assumption that, following the solvent exchange, no additional nanobubbles are introduced at significant concentrations (if present at all). Furthermore, we discuss the results in terms of the maximum surface coverage of nanobubbles that could be present on the hydrophobic surface compatibly with the sensitivity limit of these techniques.
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Affiliation(s)
| | - Marco Maccarini
- Institut Laue-Langevin , 38000 Grenoble, France
- TIMC-IMAG, Université Joseph Fourier , 38706 Grenoble, France
| | - Andrew J C Dennison
- Institut Laue-Langevin , 38000 Grenoble, France
- Department of Chemistry, Technical University Berlin , 10623 Berlin, Germany
- Department of Physics and Astronomy, University of Sheffield , S102TN Sheffield, United Kingdom
| | - Max Wolff
- Materials Physics, Department of Physics and Astronomy, Uppsala University , 75121 Uppsala, Sweden
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Mao X, Zhou R, Zhang S, Ding L, Wan L, Qin S, Chen Z, Xu J, Miao S. High Efficiency Dye-sensitized Solar Cells Constructed with Composites of TiO2 and the Hot-bubbling Synthesized Ultra-Small SnO2 Nanocrystals. Sci Rep 2016; 6:19390. [PMID: 26758941 PMCID: PMC4725357 DOI: 10.1038/srep19390] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 10/07/2015] [Indexed: 11/09/2022] Open
Abstract
An efficient photo-anode for the dye-sensitized solar cells (DSSCs) should have features of high loading of dye molecules, favorable band alignments and good efficiency in electron transport. Herein, the 3.4 nm-sized SnO2 nanocrystals (NCs) of high crystallinity, synthesized via the hot-bubbling method, were incorporated with the commercial TiO2 (P25) particles to fabricate the photo-anodes. The optimal percentage of the doped SnO2 NCs was found at ~7.5% (SnO2/TiO2, w/w), and the fabricated DSSC delivers a power conversion efficiency up to 6.7%, which is 1.52 times of the P25 based DSSCs. The ultra-small SnO2 NCs offer three benefits, (1) the incorporation of SnO2 NCs enlarges surface areas of the photo-anode films, and higher dye-loading amounts were achieved; (2) the high charge mobility provided by SnO2 was confirmed to accelerate the electron transport, and the photo-electron recombination was suppressed by the highly-crystallized NCs; (3) the conduction band minimum (CBM) of the SnO2 NCs was uplifted due to the quantum size effects, and this was found to alleviate the decrement in the open-circuit voltage. This work highlights great contributions of the SnO2 NCs to the improvement of the photovoltaic performances in the DSSCs.
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Affiliation(s)
- Xiaoli Mao
- School of Electronic Science and Applied Physics, Hefei University of Technology (HFUT), Hefei 230009, China
| | - Ru Zhou
- School of Electronic Science and Applied Physics, Hefei University of Technology (HFUT), Hefei 230009, China
| | - Shouwei Zhang
- School of Electronic Science and Applied Physics, Hefei University of Technology (HFUT), Hefei 230009, China
| | - Liping Ding
- School of Chemistry and Chemical Engineering, HFUT, Hefei, 230009, China
| | - Lei Wan
- School of Electronic Science and Applied Physics, Hefei University of Technology (HFUT), Hefei 230009, China
| | - Shengxian Qin
- School of Electronic Science and Applied Physics, Hefei University of Technology (HFUT), Hefei 230009, China
| | - Zhesheng Chen
- Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Universités-UPMC Univ. Paris 06, Paris 75005, France
| | - Jinzhang Xu
- School of Electronic Science and Applied Physics, Hefei University of Technology (HFUT), Hefei 230009, China
| | - Shiding Miao
- School of Chemistry and Chemical Engineering, HFUT, Hefei, 230009, China
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Wolff N, Gerth S, Gutfreund P, Wolff M. Temperature dependent cubic and hexagonal close packing in micellar structures. SOFT MATTER 2014; 10:8420-8426. [PMID: 25212786 DOI: 10.1039/c4sm01569j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The interfacial structure and phase diagram of a micellar solution formed by the three block copolymer (EO20-PO70-EO20) also known as P123 solved in deuterated water close to a solid boundary is investigated with respect to temperature. We find a hysteretic behavior of the d-spacing of the micellar crystal and a spontaneous change in the lateral correlation length going hand in hand with a structural reorganization between cubic and hexagonal. The phase transitions may be initiated by a change in the shape of the micelles from spherical to elongated together with a minimization of the polymer water interface.
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Affiliation(s)
- Nicole Wolff
- Crystallography and Structural Physics, University of Erlangen-Nürnberg, 91058 Erlangen, Germany
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Wolff M, Kuhns P, Liesche G, Ankner JF, Browning JF, Gutfreund P. Combined neutron reflectometry and rheology. J Appl Crystallogr 2013. [DOI: 10.1107/s0021889813024059] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Neutron reflectometry has been combined with rheology in order to investigate the solid boundary of liquids and polymers under shear deformation. This approach allows one to apply a controlled stress to a material while resolving the structural arrangements on the sub-nanometre length scale with neutron reflectivity, off-specular scattering and small-angle scattering at the same time. The specularly reflected neutron intensity of a 20% by weight solution of Pluronic F127 in deuterated water in contact with an octadecyl trichlorosilane-covered and a piranha-treated silicon wafer is evaluated. A pronounced difference is found in the structure formed by the polymer micelles at the two surfaces, which is explained by the difference in the affinity of the micellar shell to the solid interfaces. Under deformation, the near interface structure changes at deformations of about 2, 30 and 900%. The structural changes are correlated with changes in the storage and loss modulus of the polymer solution, revealing a transition from more solid to more liquid like properties.
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