Thesis
Laser enabled organic coating for functional metal surfaces
University of Iowa
Master of Science (MS), University of Iowa
Spring 2026
DOI: 10.25820/etd.008389
Abstract
Surface wettability plays a critical role in a wide range of engineering applications, including thermal management, energy systems, catalysis, and fluid transport. Among various approaches for controlling wettability, laser surface texturing has emerged as a versatile technique for fabricating hierarchical micro- and nanoscale structures that promote extreme wetting behavior. However, surface topography alone cannot reliably achieve or maintain the desired wetting state surface chemistry, particularly the type and abundance of functional groups present on the surface, plays an equally critical and often dominant role in determining wettability on laser-textured metal substrates.
To address this, a data-driven framework was developed to quantitatively analyze the combined contributions of surface chemistry and surface topography to wettability behavior. Laws' texture energy analysis was applied to scanning electron microscopy images to extract quantitative nanoscale topographical descriptors, while surface chemistry was characterized through X-ray photoelectron spectroscopy by measuring the concentration and polarity of functional groups. These descriptors were integrated into an ensemble neural network model, which confirmed that surface chemistry particularly functional group type and abundance is the dominant factor controlling wettability, while surface topography primarily governs liquid spreading dynamics. Guided by these insights, a laser-based, fully organic, and PFAS-free surface engineering strategy the Laser-Enabled Organic Coating (LASEO) process was developed to achieve stable superhydrophilic and superwicking behavior on metal alloys. Hierarchical surface structures were first created via nanosecond laser texturing to generate micro- and nanoscale features that enhance capillary transport and provide mechanical anchoring sites for coating adhesion. The surfaces were then functionalized using organic coatings derived from nanocellulose materials, including cellulose nanocrystals (CNC) and microcrystalline cellulose (MCC), as well as gel-like carbon dots (G-CDs). These materials contain abundant hydroxyl (–OH), carboxyl (–COOH), and carbonyl (C=O) functional groups, which increase surface polarity and promote strong and persistent interactions with water while preserving the underlying surface morphology.
Beyond stabilizing wettability, the hydroxyl-rich organic coatings reduce liquid–solid interfacial resistance and actively facilitate capillary-driven transport along the laser-textured microstructures. This enables sustained liquid spreading across inclined and complex geometries and establishes the coating as a functional precursor layer for subsequent water-based coating processes, allowing uniform and conformal liquid distribution without external forcing.
The wettability evolution, spreading dynamics, and wicking behavior of the treated surfaces were systematically evaluated on conventionally machined aluminum alloy and additively manufactured AlSi10Mg and Ti6Al4V substrates fabricated by laser powder bed fusion. The results demonstrate that organic coatings effectively enhance and stabilize superhydrophilic and superwicking behavior on laser-textured metal surfaces, maintaining stable wetting performance over extended environmental exposure and under repeated mechanical loading significantly outperforming laser-only treated surfaces. The LASEO process was successfully extended to additively manufactured substrates, demonstrating broad material versatility. Overall, this work establishes a data-driven and environmentally sustainable approach for designing functional surfaces with controlled wettability. By eliminating the need for fluorinated and inorganic chemicals and leveraging the dominant role of surface chemistry, the LASEO strategy provides a scalable and environmentally responsible pathway for developing durable superhydrophilic and superwicking surfaces for advanced engineering applications.
Details
- Title: Subtitle
- Laser enabled organic coating for functional metal surfaces
- Creators
- Mohammad Mohammadzadeh Sanandaji
- Contributors
- Hongtao Ding (Advisor)Ching-Long Lin (Committee Member)Albert Ratner (Committee Member)Cong Wang (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Mechanical Engineering
- Date degree season
- Spring 2026
- DOI
- 10.25820/etd.008389
- Publisher
- University of Iowa
- Number of pages
- xii, 97 pages
- Copyright
- Copyright 2026 Mohammad Mohammadzadeh Sanandaji
- Language
- English
- Date submitted
- 04/22/2026
- Description illustrations
- illustrations, graphs, tables
- Description bibliographic
- Includes bibliographical references (pages 89-97).
- Public Abstract (ETD)
Surface wettability the ability of a surface to attract or repel water plays a critical role in technologies ranging from thermal management and energy systems to medical implants and aerospace structures. The ability to engineer metal surfaces that reliably attract water and maintain that behavior over time is essential for many of these applications. Wettability is governed by two key factors: surface texture, which creates the physical pathways that guide liquid movement, and surface chemistry, which determines how strongly the surface interacts with water. However, achieving stable wettability on metal surfaces remains challenging because surface chemistry evolves under environmental exposure, causing water-attracting surfaces to gradually become water-repelling. A key question guiding this research was: which factor matters more surface texture or surface chemistry? To answer this, a machine learning framework was developed to analyze laser-processed metal surfaces and quantify the contributions of both factors. The results revealed that surface chemistry specifically the types of chemical groups present on the surface is the dominant controlling factor, while surface texture primarily influences the speed and direction of liquid spreading. This insight shifts the design approach from modifying surface structure alone to actively controlling surface chemistry.
Building on this understanding, the Laser-Enabled Organic Coating (LASEO) process was developed as a fully organic and PFAS-free surface engineering strategy. Laser texturing first creates hierarchical microscopic structures that promote liquid transport and provide strong adhesion for coatings. Natural organic coatings derived from plant-based cellulose and carbon nanoparticles are then applied, stabilizing water-attracting behavior and enhancing the ability of liquids to spread across the surface.
Importantly, these coatings not only preserve wettability but also enable liquids to move efficiently across complex and angled surfaces, making it easier to apply additional water-based coatings uniformly. The LASEO process achieves stable water-attracting behavior on both conventionally manufactured and 3D-printed metal alloys, maintaining performance under environmental exposure and mechanical stress.
By combining data-driven insights with sustainable materials, this work provides an environmentally responsible and scalable approach for engineering functional metal surfaces, with potential impact in cooling systems, fluid transport, and advanced manufacturing technologies.
- Academic Unit
- Mechanical Engineering
- Record Identifier
- 9985177375802771
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