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Modulated Light Transmission via Mag...

Gao, Jinghui,

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Modulated Light Transmission via Magneto-Responsive Janus Particle Chains /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Modulated Light Transmission via Magneto-Responsive Janus Particle Chains // Jinghui Gao.
Author:	Gao, Jinghui,
Description:	1 electronic resource (173 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-07, Section: B.
Contained By:	Dissertations Abstracts International85-07B.
Subject:	Chemical engineering. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30815070
ISBN:	9798381378184

Modulated Light Transmission via Magneto-Responsive Janus Particle Chains /
Gao, Jinghui,

Modulated Light Transmission via Magneto-Responsive Janus Particle Chains /Jinghui Gao. - 1 electronic resource (173 pages)

Source: Dissertations Abstracts International, Volume: 85-07, Section: B.

Janus particles, amphiphilic particles having two different physical and/or chemical attributes on different hemispheres, have intrigued researchers since their original conception by Pierre De Gennes in 1991. Fabrication of magnetic Janus particles having an iron oxide cap enables control of their orientation and assembly, with potential applications in displaying devices and drug delivery. In this thesis, an effective large-scale fabrication route of magnetic Janus particles is described, particle suspensions of magnetically responsive Janus particles are studied as variable emissivity fluids, and the microscopic structure of Janus particle chains in suspension is analyzed. The promise of Janus particles as bulk additives for responsive complex fluids has been limited by the inability to scale up Janus particle functionalization. Magnetic Janus particles having the high fidelity and mono-dispersity in both size and surface functionalization are fabricated utilizing particle monolayer formation and physical vapor deposition (PVD). The production rate of Janus particles is enhanced with the roll-to-roll route of depositing particle monolayers of silica or polymer colloids with various metals. Utilizing this new process for fabrication, bulk suspensions of magnetically responsive Janus particles under varying concentrations and magnetic field strengths have been utilized for variable emissivity fluids. Experimental measurements of light transmission agree well with linear models and ray tracing simulations. This work lays the foundation for further investigations of chain dynamics in manipulated magnetic fields in both Newtonian and non-Newtonian fluids. The optical response to an external magnetic field can be qualitatively explained by a kinematic model, and the time-related details of their response lead to a dynamic analysis of the averaged behavior of the Janus particle suspension microstructure. In the kinematic model, a variation of the Beer-Lambert model and ray tracing simulations capture the behavior of the experimentally measured difference in intensity between magnetically activated and nonactivated Brownian suspensions. In the dynamic analysis, different terms in a Langevin equation are discussed. Likewise, the Mason number, defined as the ratio of hydrodynamic force and magnetic force, describes the different amplitudes observed. Microscopic images obtained in both two-dimensional and three-dimensional scans via confocal microscopy reveal Janus particle chaining and microstructure evolution under static and dynamic fields. Slowing the dynamics and sedimentation using a highly viscous fluid enables in-situ observation of the dynamics of the microstructure. The shape, the size, the aspect ratio, and the orientation of each aggregate are obtained. The results describe the dynamics of chain growth, chain coalescence, chain realignment, chain distortion, and chain breaking. In summary, these findings can provide guidance on developing high performance magneto-optical suspensions and gels.

English

ISBN: 9798381378184Subjects--Topical Terms:

560457
Chemical engineering.
Subjects--Index Terms:

Colloidal suspension

Modulated Light Transmission via Magneto-Responsive Janus Particle Chains /
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520 $a Janus particles, amphiphilic particles having two different physical and/or chemical attributes on different hemispheres, have intrigued researchers since their original conception by Pierre De Gennes in 1991. Fabrication of magnetic Janus particles having an iron oxide cap enables control of their orientation and assembly, with potential applications in displaying devices and drug delivery. In this thesis, an effective large-scale fabrication route of magnetic Janus particles is described, particle suspensions of magnetically responsive Janus particles are studied as variable emissivity fluids, and the microscopic structure of Janus particle chains in suspension is analyzed. The promise of Janus particles as bulk additives for responsive complex fluids has been limited by the inability to scale up Janus particle functionalization. Magnetic Janus particles having the high fidelity and mono-dispersity in both size and surface functionalization are fabricated utilizing particle monolayer formation and physical vapor deposition (PVD). The production rate of Janus particles is enhanced with the roll-to-roll route of depositing particle monolayers of silica or polymer colloids with various metals. Utilizing this new process for fabrication, bulk suspensions of magnetically responsive Janus particles under varying concentrations and magnetic field strengths have been utilized for variable emissivity fluids. Experimental measurements of light transmission agree well with linear models and ray tracing simulations. This work lays the foundation for further investigations of chain dynamics in manipulated magnetic fields in both Newtonian and non-Newtonian fluids. The optical response to an external magnetic field can be qualitatively explained by a kinematic model, and the time-related details of their response lead to a dynamic analysis of the averaged behavior of the Janus particle suspension microstructure. In the kinematic model, a variation of the Beer-Lambert model and ray tracing simulations capture the behavior of the experimentally measured difference in intensity between magnetically activated and nonactivated Brownian suspensions. In the dynamic analysis, different terms in a Langevin equation are discussed. Likewise, the Mason number, defined as the ratio of hydrodynamic force and magnetic force, describes the different amplitudes observed. Microscopic images obtained in both two-dimensional and three-dimensional scans via confocal microscopy reveal Janus particle chaining and microstructure evolution under static and dynamic fields. Slowing the dynamics and sedimentation using a highly viscous fluid enables in-situ observation of the dynamics of the microstructure. The shape, the size, the aspect ratio, and the orientation of each aggregate are obtained. The results describe the dynamics of chain growth, chain coalescence, chain realignment, chain distortion, and chain breaking. In summary, these findings can provide guidance on developing high performance magneto-optical suspensions and gels.
546 $a English
590 $a School code: 0105
650 4 $a Chemical engineering. $3 560457
650 4 $a Polymer chemistry. $3 3173488
650 4 $a Materials science. $3 543314
650 4 $a Fluid mechanics. $3 528155
653 $a Colloidal suspension
653 $a Confocal microscope
653 $a Janus particle
653 $a Large-scale fabrication
653 $a Self-assembly
690 $a 0542
690 $a 0794
690 $a 0204
690 $a 0495
710 2 $a Lehigh University. $b Chemical Engineering. $e degree granting institution. $3 3770539
720 1 $a Gilchrist, James $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 85-07B.
790 $a 0105
791 $a Ph.D.
792 $a 2024
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30815070