Advancing functional materials through plasma technology
Carlos Ruzafa, Víctor M. Serrano and Elena Orgilés,
INESCOP Footwear Technology Centre
The footwear industry is continuously evolving, driven by the pursuit of improved functionality and performance in its products. In recent years, there has been a growing demand for durable hydrophobicity in footwear materials, as consumers seek shoes that can withstand various weather conditions without compromising comfort or style. However, achieving long-lasting water repellency has often required the use of treatments that raise concerns about chemical safety.
Recognising the need to address this challenge, researchers at INESCOP have turned their attention to plasma technology as a potential solution. Plasma, an ionised gas, offers unique properties that can be harnessed to develop advanced coating treatments for functional materials. Through its ongoing research, the organisation aims to revolutionise the footwear industry by enhancing functionality, improving chemical safety and promoting sustainability through plasma technology.
Enhancing water repellency
The research conducted so far aligns with the identified need in the footwear industry for chemical safety in treatments used to achieve durable water repellency. Many traditional methods rely on the use of chemicals that can pose risks to human health and the environment. By leveraging plasma technology, INESCOP seeks to develop coating treatments that minimise or eliminate the need for such chemicals, offering a safer alternative.
Results thus far have been promising, particularly in terms of the hydrophobicity achieved in leather and textiles studied. Plasma treatments modify the surface properties of these materials, creating a protective barrier that repels water molecules. This innovative approach not only enhances water repellency but also contributes to the durability and longevity of the materials concerned, ensuring a longer lifespan for footwear that has received plasma treatment.
Plasma technology for coating
To develop the described coatings, plasma technology is optimised by adjusting different working parameters. Electrode power, deposition time, monomer flow rate and the choice of organosilicon chemical precursor (compounds that are key single-source precursors for the synthesis of a great variety of silicon-based materials) are carefully fine-tuned to achieve the desired results.
Electrode power plays a crucial role in plasma technology as it determines the energy supplied to the system. Controlling the power precisely makes it possible to optimise the coating process and achieve the desired properties.
While higher power levels can lead to increased deposition rates, excessive power may cause damage to the material itself or result in undesired effects. Through rigorous experimentation and analysis, INESCOP has been able to identify the optimal power range for each specific coating application.
Deposition time is another parameter that significantly influences coating properties. Longer deposition times allow for thicker coatings, which may enhance durability and hydrophobicity. However, there is a delicate balance to be struck, as excessively long deposition times can lead to over coating and compromised material integrity. Extensive testing is carried out to determine the ideal deposition time for each coating formulation, ensuring optimal performance without sacrificing material quality.
Monomer flow rate is also a critical parameter in plasma technology as it controls the supply of precursor molecules to the plasma chamber. Precursor molecules are responsible for the chemical reactions that occur on the material surface during plasma treatment. By carefully adjusting the flow rate, the concentration of these molecules can be controlled to ensure uniform coating coverage. This parameter optimisation is crucial in achieving consistent and reliable functional properties across different footwear materials.
The type of organosilicon precursor used is carefully selected based on its compatibility with the desired functional properties and material composition. Organosilicon compounds offer excellent water-repellent properties and can form stable coatings on various surfaces. INESCOP evaluates different precursor options and assesses their performance in terms of water repellency, chemical safety and material compatibility. This comprehensive approach ensures that the chosen precursor aligns with the industry's need for safe and effective water repellent treatments.
Promoting sustainability
In addition to addressing chemical safety concerns, the application of plasma technology offers significant potential for promoting sustainability. Traditional coating methods often generate substantial waste and rely on environmentally harmful chemicals. In contrast, plasma technology offers a more sustainable approach by reducing waste production and minimising the release of harmful substances into the environment.
Plasma treatments also comply with stringent regulations regarding chemical safety and environmental impact. As a result, the footwear industry can meet international standards while providing functional materials that are safe for consumers and the environment. By embracing plasma technology, footwear manufacturers can contribute to a more sustainable and responsible industry.
Unlocking new possibilities
Plasma technology for coating development offers new possibilities. By tailoring plasma treatments to specific materials and desired functionalities, manufacturers can create innovative footwear products with enhanced performance attributes. Beyond water repellency, they can improve properties such as breathability, abrasion resistance and colour fastness. This versatility allows footwear to be created that meets the evolving needs of consumers while also providing superior comfort, durability and safety.
Furthermore, plasma technology can significantly enhance product performance and consumer satisfaction. Footwear that exhibits durable hydrophobicity and improved chemical safety not only meets consumer expectations but also provides added value. Whether it is a hiking boot, athletic shoe or casual sneaker, functional materials developed through plasma technology contribute to a more comfortable and pleasing user experience.
Tests have also been carried out on finished footwear with promising results. Plasma treatments applied to footwear materials do not modify the haptic properties of the shoes or the materials themselves. This ensures that shoes maintain their desired feel and texture, offering a seamless transition for consumers who value both functionality and sensory experience. In addition, product lifespan can be enhanced, reducing the frequency of replacement. This approach aligns with the industry's increasing focus on sustainability and circular economy principles.
Conclusion
INESCOP’s ongoing research in plasma technology represents a significant step forward for the footwear industry. By addressing the need for chemical safety in water repellent treatments, it aims to provide innovative and sustainable solutions. The promising results obtained in achieving hydrophobicity demonstrate the potential of plasma technology in enhancing functional materials for the footwear industry. INESCOP believes that plasma technology has the potential to transform the footwear industry, revolutionising the way functional materials are developed and integrated into footwear products. It offers improved functionality, durability and environmental responsibility, so shaping the future of functional footwear.
*This research was funded by the Valencian Institute for Business Competitiveness (IVACE) of Generalitat Valenciana and the European Regional Development (ERDF), grant number IMDEEA/2023/61, NANO4COAT.
Hydrophobic leather boot waterproofed by plasma coating.
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