Part 1 of a Chromis Technologies series on using AFPs for precise surface control
Introduction
In many technology sectors, such as semiconductors and bioengineering, the performance of advanced materials often hinges on their surface properties rather than bulk characteristics. Plasma etching and corona treatment are traditional tools for modifying polymer surfaces. Coatings of amorphous fluoropolymers (AFPs) can also change the surface properties of an underlying material. AFPs can enable a fundamentally different approach, as well – the ability to design specific surface characteristics into the material itself.
This article, the first in a series, discusses how combining typical fluoropolymer traits with an amorphous structure makes AFPs powerful tools for surface engineering, offering advantages in uniformity, durability, and tailored functionality for demanding applications in electronics, optics and photonics, digital microfluidics, and gas separations. Future entries will explore these and other use cases in more detail.
Magic Happens at the Surface
In the world of advanced materials, the surface is the interface that determines how a component behaves in relation to its environment – whether it adheres, repels, resists wear, conducts signals, or interacts with biological systems. As technologies push the boundaries in fields like microelectronics, medical devices, and advanced optics, ensuring that a material’s surface properties behave exactly as needed has become critical.
For decades, engineers have relied on techniques like plasma treatment, corona discharge, chemical etching, or applying thin coatings to modify the surfaces of conventional polymeric materials. These methods primarily aim to alter surface energy, typically increasing it to improve adhesion or wettability. While effective for many applications, these post-treatments can have limitations:
- Line-of-sight dependencies (e.g., only effective on areas directly exposed to the treatment source)
- Potential surface damage (e.g., pitting, chemical degradation, discoloration, fluorine residues)
- Temporary effects (e.g., short-lived surface activation)
- Incompatibility with delicate micro-/nano-structures (e.g., microfluidic channel erosion)
- Lack of specificity needed for highly complex surface functionalities (e.g., over-or under-treatment of critical areas)
AFPs are unique in their potential for coating other materials and for what can be done to their surfaces, but also for what is already engineered into them.
Enter Amorphous Fluoropolymers
At Chromis Technologies, we specialize in a unique class of materials – amorphous fluoropolymers. As we’ve discussed previously in Amorphous Fluoropolymers: A Revolution in Advanced Materials, AFPs combine the well-known, outstanding properties of traditional fluoropolymers like polytetrafluoroethylene (PTFE) – exceptional chemical inertness, thermal stability, low dielectric constant, and inherent lubricity – with the benefits derived from their amorphous structure – high optical clarity and, crucially for processing and surface engineering, solubility in specific fluorinated solvents. This combination unlocks powerful possibilities for controlling surfaces.
Compared to semi-crystalline fluoropolymers like PTFE, AFPs exhibit:
- Superior optical transparency
- Smoother, defect-free surfaces
- Solubility in fluorinated solvents for thin-film application
- Better compatibility with high-precision patterning
These traits aren’t simply byproducts – they’re design features.
Surface Engineering: The AFP Advantage
Instead of merely treating a surface after the fact, AFPs allow us to design and engineer surface properties in several ways:
Leveraging Inherent Properties
The fundamental chemistry of fluoropolymers yields an inherently low surface energy (~15-20 mN/m), making them water and oil repellent and anti-friction/-adhesive. These properties are ideal for applications requiring fouling resistance or lubricant-free performance. CYTOP® and CyclAFlor® coatings have demonstrated contact angles exceeding 100° – comparable to treated PTFE – and can produce exceptionally smooth, non-porous surfaces without requiring aggressive treatments, which is critical for applications demanding nanoscale uniformity.
Processability for Superior Surfaces
Because many AFPs can be dissolved in fluorinated solvents, they can be applied as thin, highly uniform coatings via techniques like spin-coating, dip-coating, or spray-coating. This allows for precise thickness control and conformal coverage over complex geometries, which may be difficult to achieve uniformly with plasma or corona treatments. The ability to apply AFPs from solution also opens doors to incorporating other functional molecules directly into the coating formulation, although that’s a topic for a deeper dive in a future article.
Designing by Choice, Not Just Treatment
AFPs allow you to select materials that already possess many of the desired surface characteristics or can be processed to achieve them directly. This contrasts sharply with taking a less suitable bulk material and applying an energetic surface treatment (like plasma modification, which alters only the top few nanometers). An AFP-based surface is integral to the material or coating itself, often leading to greater durability and stability, especially in harsh chemical or thermal environments.
Potential for Molecular-Level Tailoring
Beyond leveraging inherent properties and processability, the chemical structure of AFPs offers possibilities for specific functionalization through molecular design. Researchers have used techniques such as silane coupling, vacuum ultraviolet (VUV) radiation, and x-ray grafting to introduce polar groups, tune wettability, or improve metal adhesion of fluoropolymers (Kang & Zhang, 2000). Silane doping has enabled CYTOP-based electret films to achieve surface charge densities up to 1.5 mC/cm², with improved thermal stability for power generation and MEMS applications (Sakane, Suzuki, & Kasagi, 2008).
While outside the scope of this introduction, Chromis Technologies is exploring novel copolymer compositions and ways to chemically modify AFP backbones or side chains to introduce specific binding sites, alter wettability precisely, or create patterned surfaces. Our research envisions a future where surfaces can be meticulously programmed for highly specific interactions.
Why Does This Matter for Your Application?
Choosing an AFP-based approach for surface engineering can offer significant advantages:
- Uniformity – Solution-based coating methods allow for highly uniform surfaces over large areas.
- Durability – Surface properties are integral to the AFP material, not just a thin treated layer, leading to better longevity.
- Tunability – Leverage inherent properties or explore processing/formulation options to fine-tune surface energy, wettability, and other characteristics.
- Synergy – Combine desired surface properties with the excellent bulk properties of AFPs (e.g., optical clarity and anti-reflective surface, chemical inertness and specific biocompatibility).
The unique surface properties of AFPs make them enabling materials across diverse, high-tech fields:
- Microelectronics & Semiconductors – Dielectric layers, anti-stiction coatings for nanoimprint lithography, protective layers.
- Medical Devices – Biocompatible and lubricious coatings for catheters or implants, components for microfluidic diagnostic devices.
- Optics & Photonics – Anti-reflective coatings, core and cladding layers for optical and sensing fibers.
- Advanced Manufacturing – High-performance mold release coatings.
- Chemical Processing – Chemically resistant and anti-fouling linings or coatings.
Conclusion: The Surface is Just the Beginning
Amorphous fluoropolymers offer more than just outstanding bulk material properties; they provide a sophisticated platform for engineering surfaces with precisely controlled characteristics. By leveraging their inherent low surface energy, smoothness, processability, and potential for molecular tailoring, AFPs enable performance levels and functionalities that can be challenging or impossible to achieve with traditional materials and surface treatments alone. This ability to design the surface opens up new possibilities for innovation across demanding industries.
Next Steps in the Series
This article serves as an introduction to the concept of surface engineering with AFPs. In our next installment, we will dive deeper into one of the most fundamental surface characteristics: wettability. We’ll explore how AFPs provide inherent hydro- and oleo-phobicity and discuss strategies for potentially tuning these properties for applications requiring specific liquid interactions. Stay tuned!
Have a surface challenge? Contact Chromis Technologies today to discuss how our amorphous fluoropolymers might provide the solution.
References
Hegemann, D., Brunner, H., & Oehr, C. (2003). Plasma treatment of polymers for surface and adhesion improvement. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 208, 281–286. https://doi.org/10.1016/S0168-583X(03)00644-X
Kang, E. & Zhang, Y.. (2000). Surface Modification of Fluoropolymers via Molecular Design. Advanced Materials. 12. 1481 – 1494. https://doi.org/10.1002/1521-4095(200010)12:20<1481::AID-ADMA1481>3.0.CO;2-Z
Chromis Technologies. (2025, January 31). Amorphous fluoropolymers: A revolution in advanced materials. Chromis Technologies. https://chromistechnologies.com/blog/amorphous-fluoropolymers-a-revolution-in-advanced-materials/
Popovici, D., Meunier, M., & Sacher, E. (1999). Laser-Enhanced Gas Phase Surface Modifications of Teflon AF1600 for Increased Copper Adhesion. The Journal of Adhesion, 70(1–2), 155–165. https://doi.org/10.1080/00218469908010492
Sakane, Y., Suzuki, Y., & Kasagi, N. (2008). Development of a high-performance perfluorinated polymer electret and its application to micro power generation. Journal of Micromechanics and Microengineering, 18(10), 104011. https://doi.org/10.1088/0960-1317/18/10/104011
Son, T. Y., Jeong, M. A., & Nam, S. Y. (2018). Amorphous fluoropolymer membrane for gas separation applications. Journal of Nanoscience and Nanotechnology, 18(9), 6206–6212. https://doi.org/10.1166/jnn.2018.15641
J. Matienzo, J. A. Zimmerman, F. D. Egitto; Surface modification of fluoropolymers with vacuum ultraviolet irradiation. J. Vac. Sci. Technol. A 1 September 1994; 12 (5): 2662–2671. https://doi.org/10.1116/1.579086
Siperko, L.M., & Thomas, R.R. (1989). Chemical and physical modification of fluoropolymer surfaces for adhesion enhancement: a review. Journal of Adhesion Science and Technology, 3, 157-173. https://doi.org/10.1163/156856189X00137
Okubo, M., Tahara, M., Aburatani, Y., Kuroki, T., & Hibino, T. (2010). Preparation of PTFE Film With Adhesive Surface Treated by Atmospheric-Pressure Nonthermal Plasma Graft Polymerization. IEEE Transactions on Industry Applications, 46, 1715-1721. https://doi.org/10.1109/TIA.2010.2057492
Liang, L., Wen, T., Xin, J., Su, C., Song, K., Zhao, W., Liu, H., & Su, G. (2023). Fluoropolymer: A Review on Its Emulsion Preparation and Wettability to Solid-Liquid Interface. Molecules (Basel, Switzerland), 28(2), 905. https://doi.org/10.3390/molecules28020905
FAQs
What is advanced materials engineering?
Compared to conventional materials, advanced material engineering is a discipline focused on developing materials with enhanced or completely novel properties like superior strength-to-weight, specific electrical characteristics, or self-healing and shape-memory capabilities. It involves understanding and manipulating material structure at an atomic level up, utilizing sophisticated synthesis and processing techniques, and creating tailored solutions like advanced composites, ceramics, polymers, nanomaterials, and biomaterials that drive innovation across industries like aerospace, electronics, medicine, and energy.
What is material surface engineering?
Material surface engineering involves altering the outermost layer of a material to give it specific properties or functionalities that are different from the bulk material underneath. The main goal is to improve performance by enhancing surface characteristics like resistance to wear, corrosion, or fatigue, controlling friction, improving biocompatibility, changing appearance, or modifying electrical or thermal properties. This is achieved using a wide range of techniques, such as applying thin coatings (where the surface properties are primarily those of the coating material) or modifying the existing surface structure and chemistry, thereby optimizing components for their specific operating environment and extending their service life.
Why do we need surface engineering?
The surface of a material is where it interacts with its environment, and this interaction often dictates the component’s overall performance, durability, and lifespan. A material chosen for its bulk properties (like strength, weight, or cost) may not have the ideal surface characteristics required for its specific application. By manipulating the surface and underlying bulk material separately, surface engineering can:
- Combat Degradation: Enhance resistance to common failure modes like wear, corrosion, erosion, and fatigue, which predominantly initiate at the surface.
- Optimize Performance: Modify surface properties like friction (making surfaces slippery or grippy), heat transfer, electrical conductivity, or optical characteristics (color, reflectivity).
- Add Functionality: Introduce new capabilities such as biocompatibility for medical implants, catalytic activity for chemical reactions, or self-cleaning properties.
- Enable Cost-Effective Design: Use less expensive or lighter core materials while achieving high performance at the surface, rather than making the entire component from a costly specialty material.
- Extend Component Life: Significantly increase the service life of parts operating in demanding conditions by protecting the underlying material.
Basically, surface engineering provides tailored solutions to overcome the limitations of bulk materials, enabling components to function reliably and efficiently in their specific operating environments.