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Wu H, Qin J, Hua X, Wang Z, Zhang Z, Zhang J. Self-assembly behavior and adhesive performance of imidazolium cation grafted cellulose nanocrystals in confined space. Carbohydr Polym 2024; 336:122127. [PMID: 38670758 DOI: 10.1016/j.carbpol.2024.122127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 03/28/2024] [Accepted: 04/02/2024] [Indexed: 04/28/2024]
Abstract
Confined evaporation-induced self-assembly (C-EISA) is a powerful technique to guide disordered nanoparticles into long-range organized structures. Herein, we investigate the C-EISA behavior of 1-butyl-3-vinylimidazolium cation ([VBIm]+) grafted cellulose nanocrystals (CNC-C) in a parallel-plates confined geometry. Interestingly, CNC-C can spontaneously assemble into maze-like patterns with branch dimensions on the micrometer scale and uniformly distributed throughout the confined space, which is completely different from the lamellar self-assembly patterns of unmodified CNCs. Combining in situ observations and microscopic characterization, we speculate that the formation of maze-like patterns originates from the reduction of colloidal stability induced by the grafted imidazolium cations. The electrostatic attraction between CNC-C aggregated bundles and glass substrates acts as anchor points, thereby leading to the unstable motion of the liquid-air menisci during the inward intrusion of air. Due to the physicochemical properties and unique C-EISA behavior, the CNC-C based adhesive can maintain adhesion at temperatures of ca. 200 °C, while rapidly debonding when immersed in water, demonstrating the potential to be used as stimuli-responsive temporary or removable adhesives. Furthermore, the strategy proposed in this work for achieving CNCs patterning is also promising to be extended to other anisotropic rod-shaped nanoparticles.
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Affiliation(s)
- Hao Wu
- Key Laboratory of Rubber-Plastics, Ministry of Education, Shandong Provincial Key Laboratory of Rubber-plastics, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Jinli Qin
- Key Laboratory of Rubber-Plastics, Ministry of Education, Shandong Provincial Key Laboratory of Rubber-plastics, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Xiangdong Hua
- Key Laboratory of Rubber-Plastics, Ministry of Education, Shandong Provincial Key Laboratory of Rubber-plastics, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Zhaolu Wang
- Key Laboratory of Rubber-Plastics, Ministry of Education, Shandong Provincial Key Laboratory of Rubber-plastics, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Zejun Zhang
- Key Laboratory of Rubber-Plastics, Ministry of Education, Shandong Provincial Key Laboratory of Rubber-plastics, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Jianming Zhang
- Key Laboratory of Rubber-Plastics, Ministry of Education, Shandong Provincial Key Laboratory of Rubber-plastics, Qingdao University of Science & Technology, Qingdao 266042, China.
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Paul A, Roy A, Dhar P. External Stefan and Internal Marangoni Thermo-Fluid Dynamics for Evaporating Capillary Bridges. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:5255-5269. [PMID: 38412068 DOI: 10.1021/acs.langmuir.3c03703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/29/2024]
Abstract
We probe the evaporation mechanisms of wettability-moderated, confined capillary bridges and bulges. For the first time, we explore the internal Marangoni hydrodynamics and external Stefan advection dynamics in the surrounding gaseous domain due to evaporative effects. A transient simulation approach based on the level set (LS) method and the Arbitrary Lagrangian-Eulerian (ALE) framework was adopted to computationally model the capillary bridge profiles and evaporation phenomenon with generic contact line dynamics (both CCR and CCA modes). The governing equations corresponding to the transport processes in both the liquid and gaseous domains are simulated in a fully coupled manner with appropriate boundary conditions to precisely trace the liquid-vapor interface and the three-phase contact point during evaporation. The effect of the bridge confinement phenomenon, i.e., the extent of confined ambient surrounding the liquid-vapor interface between the solid surfaces, is explored. Also, the role of wetting state and contact line dynamics during CCR and CCA modes of evaporation were probed, and good agreement with experimental observations was noted. Results show that the evaporation rate is primarily dictated by the confinement phenomenon, and wettability effects play a marginal role. A higher confinement curtails the evaporation rate due to an increased local vapor concentration around the liquid bridges. However, the wetting state substantially affects the internal Marangoni effect dynamics and the Stefan advection dynamics due to its explicit influence on the nonuniform evaporative flux along the liquid-vapor interface. Between superhydrophobic confinements, the contact lines are confined in the wedge-shaped region, thereby locally augmenting the vapor concentration. As a result, the large evaporative flux near the bulge region develops a higher temperature gradient, thereby inducing upscaled thermal Marangoni flow compared to hydrophilic confinements. These findings may have significant implications for the efficient designing and development of thermofluidic systems involving thermal transport, mixing, and deposition of dissolved particles in liquid bridges.
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Affiliation(s)
- Arnov Paul
- Hydrodynamics and Thermal Multiphysics Lab (HTML), Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Apurba Roy
- Hydrodynamics and Thermal Multiphysics Lab (HTML), Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Purbarun Dhar
- Hydrodynamics and Thermal Multiphysics Lab (HTML), Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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Gonzalez AV, Gonzalez M, Hanrath T. Emergence and inversion of chirality in hierarchical assemblies of CdS nanocrystal fibers. SCIENCE ADVANCES 2023; 9:eadi5520. [PMID: 37939188 PMCID: PMC10631732 DOI: 10.1126/sciadv.adi5520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023]
Abstract
Arranging semiconducting nanocrystals into ordered superstructures is a promising platform to study fundamental light-matter interactions and develop programmable optical metamaterials. We investigated how the geometrical arrangement of CdS nanocrystals in hierarchical assemblies affects chiroptical properties. To create these structures, we controlled the evaporation of a colloidal CdS nanocrystal solution between two parallel plates. We combined in situ microscopy and computational modeling to establish a formation mechanism involving the shear-induced alignment of nanocrystal fibers and the subsequent mechanical relaxation of the stretched fibers to form Raman noodle-type band textures. The high linear anisotropy in these films shares many similarities with cholesteric liquid crystals. The films deposited on top and bottom surfaces exhibit opposite chirality. The mechanistic insights from this study are consequential to enable future advances in the design and fabrication of programmable optical metamaterials for further development of polarization-based optics toward applications in sensing, hyperspectral imaging, and quantum information technology.
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Affiliation(s)
- Alexander V. Gonzalez
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Miranda Gonzalez
- Department of Materials Science, Arizona State University, Tempe, AZ 85281, USA
| | - Tobias Hanrath
- Robert F. Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14853, USA
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Paul A, Samanta D, Dhar P. Evaporation kinetics of wettability-moderated capillary bridges and squeezed droplets. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.118267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Deka N, Saha S, Dash S. Evaporation-induced convective transport in confined saline droplets. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.128256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Mohammadrezaei S, Siavashi M, Asiaei S. Surface topography effects on dynamic behavior of water droplet over a micro-structured surface using an improved-VOF based lattice Boltzmann method. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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He X, Cheng J. Evaporation-triggered directional transport of asymmetrically confined droplets. J Colloid Interface Sci 2021; 604:550-561. [PMID: 34274716 DOI: 10.1016/j.jcis.2021.06.164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/27/2021] [Accepted: 06/28/2021] [Indexed: 11/15/2022]
Abstract
HYPOTHESIS When a liquid droplet is confined between two non-parallel hydrophobic surfaces with dihedral angle α, its behavior is largely influenced by the asymmetric confinement. During evaporation, the droplet morphology under confinement will continuously evolve, leading to the directional transport of the droplet towards the cusp. EXPERIMENTS AND SIMULATIONS During the evaporation process, droplets at different initial locations l0 from the cusp were experimentally observed to transport towards the cusp. A series of simulations using Surface Evolver were performed to obtain the three-dimensional morphologies of the confined droplets. Force and energy analyses were conducted to unveil the mechanisms dominating the evaporation-triggered actuation and transport. FINDINGS The asymmetrically confined droplet of volume V would drift towards an equilibrium location of le from the cusp with the lowest energy. Its directional motion results from the consecutively decreasing le, which is scaled as le~α-1V13 during evaporation. Herein, the creeping and slipping modes of transport could be characterized as the quasi-stable and unstable self-relaxation processes of droplet from the stretched regime to the equilibrium regime, respectively. Our findings on the intrinsic mechanism of droplet actuation shed light on a novel approach to manipulating the confined droplet behaviors in a passive and decisive fashion.
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Affiliation(s)
- Xukun He
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Jiangtao Cheng
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, VA 24061, USA; Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA; Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA 24061, USA.
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Upadhyay G, Bhardwaj R. Colloidal Deposits via Capillary Bridge Evaporation and Particle Sorting Thereof. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12071-12088. [PMID: 34609891 DOI: 10.1021/acs.langmuir.1c01869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Evaporating droplets of colloidal suspensions leave behind particle deposits which could be effectively controlled via manipulating the surrounding conditions and particles and liquid properties. While previous studies extensively focused on sessile and pendant droplets, the present work investigates the evaporation dynamics of capillary bridges of colloidal suspensions formed between two parallel plates. We vary the wettability of the plates and the particle size and composition of the colloidal suspensions, keeping the same spacing between the plates. We employ side visualization, optical microscopy, fluorescence microscopy, and scanning electron microscopy and develop computational and theoretical models to collect the data. A computational model based on diffusion-limited evaporation is used to characterize the timescale of the evaporation of the capillary bridge. The model predictions are in good agreement with the present and prior experimental measurements. We discuss about the deposits of monodispersed particle suspension formed by the interplay of pinning of the contact line and evaporation dynamics. Multiple rings on the plates are observed due to the stick-slip motion of the contact line. The larger particles tend to form asymmetric deposits, with most particles concentrated on the bottom plates due to a considerably stronger gravitational pull than the hydrodynamic drag. This deposition is explained by estimating the competing forces on the particles during the evaporation. A regime map is proposed for classifying deposits on the particle size wettability plane. Lastly, we demonstrate size-based particle sorting of bidispersed colloidal suspensions in this framework. We describe two mechanisms: gravity-assisted and geometry-assisted sorting, which can be designed to sort particles efficiently. A regime map depicting the regions of influence of each mechanism is presented.
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Affiliation(s)
- Gaurav Upadhyay
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Rajneesh Bhardwaj
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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Zhu P, Zhang H, Lu H. Preparation of Polyetherimide Nanoparticles by a Droplet Evaporation-Assisted Thermally Induced Phase-Separation Method. Polymers (Basel) 2021; 13:polym13101548. [PMID: 34065994 PMCID: PMC8150268 DOI: 10.3390/polym13101548] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/07/2021] [Accepted: 05/08/2021] [Indexed: 11/23/2022] Open
Abstract
The droplet evaporation effect on the preparation of polyetherimide (PEI) nanoparticles by thermally induced phase separation (TIPS) was studied. PEI nanoparticles were prepared in two routes. In route I, the droplet evaporation process was carried out after TIPS. In route II, the droplet evaporation and TIPS processes were carried out simultaneously. The surface tension and shape parameters of samples were measured via a drop shape analyzer. The Z-average particle diameter of PEI nanoparticles in the PEI/dimethyl sulfoxide solution (DMSO) suspension at different time points was tested by dynamic light scattering, the data from which was used to determine the TIPS time of the PEI/DMSO solution. The natural properties of the products from both routes were studied by optical microscope, scanning electron microscope and transmission electron microscope. The results show that PEI nanoparticles prepared from route II are much smaller and more uniform than that prepared from route I. Circulation flows in the droplet evaporation were indirectly proved to suppress the growth of particles. At 30 °C, PEI solid nanoparticles with 193 nm average particle size, good uniformity, good separation and good roundness were obtained. Route I is less sensitive to temperature than route II. Samples in route I were still the accumulations of micro and nanoparticles until 40 °C instead of 30 °C in route II, although the particle size distribution was not uniform. In addition, a film structure would appear instead of particles when the evaporation temperature exceeds a certain value in both routes. This work will contribute to the preparation of polymer nanoparticles with small and uniform particle size by TIPS process from preformed polymers.
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Zhang R, Liao W, Wang Y, Wang Y, Ian Wilson D, Clarke SM, Yang Z. The growth and shrinkage of water droplets at the oil-solid interface. J Colloid Interface Sci 2021; 584:738-748. [PMID: 33317712 DOI: 10.1016/j.jcis.2020.09.102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/24/2020] [Accepted: 09/25/2020] [Indexed: 11/17/2022]
Abstract
HYPOTHESIS The mechanism for the spontaneous formation of water droplets at oil/solid interfaces immersed in water is currently unclear. We hypothesize that growth and shrinkage of droplets are kinetically controlled by diffusion of water through the oil, driven by differences in chemical potential between the solid substrate and the aqueous reservoir. EXPERIMENTS The formation, growth and shrinkage of water droplets at an immersed oil/solid interface are investigated theoretically and experimentally with three silicone oils. The surface is hydrophobic and the droplets formed are truncated spheres with radius, a, less than 10 μm. The expansion and contraction of the droplets can be controlled by adjusting the difference in chemical potential. The growth kinetics are modelled in terms of water migration through the oil layer which predicts a2∝t. FINDINGS This is the first study of possible mechanisms for the formation of such interfacial droplets. Several possible causes are shown to be unfavourable, negligible, or are eliminated by careful experiments controlling key parameters (such as oil viscosity, substrate chemistry). The rate constant for mass transport is proportional to difference in chemical potential and an estimate shows dissociation of surface groups on the substrate provides a driving chemical potential of the right magnitude.
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Affiliation(s)
- Ran Zhang
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Wei Liao
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yunpeng Wang
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yao Wang
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - D Ian Wilson
- Department of Chemical Engineering and Biotechnology, Philippa Fawcett Drive, University of Cambridge, Cambridge CB3 0AS, UK.
| | - Stuart M Clarke
- Department of Chemistry and BP Institute, Madingley Rise, University of Cambridge, Cambridge CB2 1EW, UK.
| | - Zhongqiang Yang
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China.
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