Advancing porous heat transfer materials and polymer coatings with photonic structures

Singhal, Gaurav

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https://hdl.handle.net/2142/122240 Copy

Description

Title

Advancing porous heat transfer materials and polymer coatings with photonic structures

Author(s)

Singhal, Gaurav

Issue Date

2023-11-30

Director of Research (if dissertation) or Advisor (if thesis)

Braun, Paul V

Doctoral Committee Chair(s)

Braun, Paul V

Committee Member(s)

• Schroeder, Charles
• Chen, Qian
• Miljkovic, Nenad

Department of Study

Materials Science & Engineerng

Discipline

Materials Science & Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Inverse opals
• holography
• thermal coatings
• porous metals
• plasmonics
• metal architectures
• polymer coatings
• difuusion.

Abstract

Multi-dimensional photonic structures have been extensively explored for various applications, including waveguides, filters, and lenses. Metallic counterparts of such structures have been explored for their application in heat transfer and sensing. However, there has been a noticeable gap in research regarding the optical-based fabrication and optical applications of two- and three-dimensional metallic structures in the realms of heat transfer and polymer science. This can be attributed to reliance on methods that are less scalable and difficulty of using optical methods on substrates that can cause additional problems like reflection. This research addresses this gap by utilizing two- and three-dimensional metallic structures to solve critical challenges in these fields. This thesis critically evaluates a particular class of multi-dimensional photonic structures, specifically the templated electroplated metallic copper inverse opals (CIO) with densely packed pores. It comprehensively examines their electrical, thermal, and mechanical properties, as detailed in Chapter Two. While CIOs demonstrate an encouraging electrical conductivity of roughly 15% compared to pure copper, in line with structural expectations and measured electroplated copper conductivity, their thermal reliability is a cause for concern. Consequently, the study pivots to the application of interference lithography, leveraging a copper oxide anti-reflection coating (nCO) that can be electrochemically reduced to copper metal. This advancement facilitates the creation of three-dimensionally structured templates on reflective substrates, a concept discussed in Chapter Three. The resultant nCO structures display exceptional radiation absorbance, and their ability to be converted into copper metal during electrochemical deposition of metal, significantly enhances two-phase cooling applications. In addition, two-dimensional plasmonic structures are employed to address the critical need for a robust method offering high temporal and spatial resolution in characterizing molecular transport within polymers. This necessity holds immense importance across diverse sectors, including pharmaceuticals, textiles, and food and beverage packaging, as well as within the broader polymer science community. By leveraging the amplified infrared (IR) absorbance sensitivity of plasmonic nanoantenna-based surface-enhanced infrared absorption (SEIRA), a novel approach is introduced in Chapter Four. For the study of self-stratifying polyurethane coatings in Chapter Five, traditional methods are adopted due to the limitations of plasmonic structures for thicker coatings. This investigation yields valuable insights into the self-stratification process when hydrophobic and hydrophilic polyols and prepolymers are carefully mixed under controlled conditions, as verified through techniques such as SIMS, XPS, and confocal Raman spectroscopy. Ultimately, this research contributes to the advancement of efficient coating applications, benefiting a broad spectrum of surfaces. Collectively, these research efforts has made significant advances in the field of multi-dimensional photonics structures by successfully applying the two and three-dimensional metallic structures in the field of heat transfer and polymer science. We have successfully demonstrated application of structure copper oxide as anti-reflection coating for optical fabrication methods like interference lithography and proximity field nano-patterning. This work opens up a new avenue for fabricating structures with high surface area to volume ratio for higher critical heat flux (CHF) applications as we demonstrate with the help of two-phase cooling experiments where we see three times improvement when compared with CHF of bare silicon substrate. This work also overcome the problems associated with the colloidal self-assembly method like template cracking and delamination which affects the scalability to industrial scales. Further, we demonstrate significant enhancement in infrared absorbance sensitivity through plasmonic nanoantenna-based surface-enhanced infrared absorption (SEIRA) within a 50 nm proximity of a thin film under investigation, enabling precise detection of trace analytes and diffusion measurements in thin polymer films. Compared to a standard attenuated total internal reflection (ATR) system, this method improves the limit of detection by at least 13-fold and reduces the detection volume by approximately 15-fold, facilitating the determination of diffusion coefficients and solubility’s of specific molecules in thin polymer films, including L-ascorbic acid, ethanol, sugars, and water in various mixtures. Acknowledging the limit of SEIRA technique for thin film studies, we used conventional characterization studies to analyze polyurethane self-stratifying coating system and prove that the interfacial energy can be used as driving force for stratification in such systems and achieve the desired result.

Graduation Semester

2023-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/122240

Copyright and License Information

Copyright 2023 Gaurav Singhal

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