Many sectors, especially the food, textile, and automotive industries, use pigments for aesthetic and technical purposes.1
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Pigments are compounds that provide specific colors to items. Early human civilizations used pigments daily, and with industrial expansion and the development of synthetic pigments, their use has become widespread.2
Innovative Pigment Technologies
The development of pigments has advanced significantly, particularly in response to growing environmental concerns. This has driven the shift from artificial to natural pigments,3 emphasizing the need for more sustainable and eco-friendly solutions.
Traditional extraction methods for natural pigments were straightforward and inexpensive but environmentally harmful. Recently, environmentally friendly extraction methods have been explored, and alternatives have been proposed.4
Techniques such as ultrahigh pressure, ultrasound, pulsed electric fields, supercritical fluid extraction, and high-pressure homogenization are now used to synthesize natural colorants like polyphenols, carotenoids, chlorophylls, and betalains.5
Researchers have developed pigments to protect metals from rust, such as the cerium-diethyl dithiocarbamate complex (Ce-DEDTC), which protects the aluminum alloy 2024-T3 used in aerospace.
Experiments showed this alloy resisted corrosion better when coated with Ce-DEDTC, forming a thin protective film that stops harmful substances from reaching the metal. This coating also enhanced electrical conductivity. Electrochemical Impedance Spectroscopy showed that samples with Ce-DEDTC improved corrosion resistance by a factor of 100 compared to pure aluminum.6
Nanoparticles are being added to modern pigments to improve their attributes. A research paper describes a technique for synthesizing photonic crystals using amorphous photonic crystals (APCs) and black TiO2-x nanocomposite pigments, creating vivid, non-reflective photonic structures with excellent color, visibility, and photocatalytic capability.7 The environmentally friendly properties and catalytic efficiency of titanium dioxide make it suitable for this purpose.
By absorbing scattered light, black TiO2-x nanoparticles increased the color saturation of these pigments. The slow light effect from the pseudo band gap in SiO2 APCs, combined with full-spectrum absorption of the nanoparticles, enhanced the efficiency of photogenic carriers. The color and intensity of these pigments can be adjusted by changing the size of the SiO2 nanospheres and the amount of TiO2-x nanoparticles, making this method useful for various applications.
Industrial Applications of Modern Pigments
Modern pigments extracted from microorganisms are beneficial, leading the food industry, pharmaceutical companies, and paint and bioplastic startups to invest in research. These pigments offer prolonged shelf life and inherent antioxidant properties, making them popular.2
In the cosmetics and fashion industry, natural pigments like Phycocyanin from Spirulina are used in bio-lipsticks, bio-eyeliners, bio-eye shadows, creams, and soaps.
The electronics sector also uses pigments like Diketopyrrolopyrrole (DPP), a carbon-based organic material valued for its color and charge transport capabilities in optoelectronic devices. These pigments can be printed on various materials, enabling flexible materials to become solar cells, transistors, and sensors, with applications in medical devices and eco-friendly technology products.8
The beneficial features of pigments are encouraging their integration into commercial setups. Addressing the negative impacts of plastic products, researchers from Brazil and Portugal developed biodegradable plastic using pigments from yeast.
After over eight years of research, they showed that eutectic solvents could extract carotenoids, astaxanthin, and beta-carotene from the yeast Phaffia rhodozyma. The next step is testing this biodegradable plastic for food packaging, with promising results expected.9
Challenges in Pigment Development
Bringing versatile therapeutic or industrially important pigment products to market requires substantial investment and experimental work. The high costs associated with pigment production remain a significant challenge.
Additionally, it is crucial to conduct technical assessments of color stability under various conditions, such as heat, light (photolysis), pH, agitation, aeration, and dissolved oxygen, along with studying solubility.
Although these technical factors are essential for the successful application of pigments in various technologies, they require specialized equipment and the development of meticulous testing processes.2
Regulatory approvals from EU and USA legislations and the Food and Drug Administration (FDA) are essential but can delay product release and make innovation more challenging. Additionally, some pigments contain harmful metallic substances like lead and mercury, which are toxic to humans and the environment and contribute to air pollution.10
Governments worldwide are working to switch to more eco-friendly alternatives for pigment development. Researching new methods to create pigments from alternative sources presents another significant challenge.
Future Prospects
Although many technological and regulatory issues exist, innovations are boosting the pigment industry. The automotive industry relies on pigments, with companies making significant strides in modern pigment development. Effect pigments are expected to play a key role in creating unique appearances, offering vivid colors and special effects like metallic finishes, high sparkle, and strong interference effects.11
Autonomous systems also rely on pigments, with startups focusing on developing pigments that enhance system functionality. For example, self-driving cars depend on RADAR and LiDAR systems to communicate with their surroundings. As a result, modern pigments are being developed to enhance signal transmission from vehicles and improve signal reflection from surrounding objects.12
Overall, sustainability is crucial in all applications of modern pigments, as strict environmental regulations can hinder marketability and profitability.
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References and Further Reading
[1] Yadav, S. et al. (2023). A brief review on natural dyes, pigments: Recent advances and future perspectives. Results in Chemistry. doi.org/10.1016/j.rechem.2022.100733
[2] Ramesh, C., et al. (2019). Multifaceted Applications of Microbial Pigments: Current Knowledge, Challenges and Future Directions for Public Health Implications. Microorganisms. doi.org/10.3390/microorganisms7070186
[3] López-Cruz, R. et al. (2023). Plant Pigments: Classification, Extraction, and Challenge of Their Application in the Food Industry. Food Bioprocess Technol. doi.org/10.1007/s11947-023-03075-4
[4] Jurić, S., et al. (2022). Sources, stability, encapsulation and application of natural pigments in foods. Food Reviews International. doi.org/10.1080/87559129.2020.1837862
[5] López-Cruz, R. (2023). Plant Pigments: Classification, Extraction, and Challenge of Their Application in the Food Industry. Food Bioprocess Technol. doi.org/10.1007/s11947-023-03075-4
[6] Mohammadi, I., et al. (2020). Cerium/diethyldithiocarbamate complex as a novel corrosion inhibitive pigment for AA2024-T3. Sci Rep. doi.org/10.1038/s41598-020-61946-8
[7] Feng, L., et al. (2022). The Development of New Catalytic Pigments Based on SiO2 Amorphous Photonic Crystals via Adding of Dual-Functional Black TiO2-x Nanoparticles. ACS omega. doi.org/10.1021/acsomega.2c00346
[8] QUT. Research Turning Coloured Pigments into Electronics. [Online]. QUT. Available at: https://www.qut.edu.au/news?id=159513&utm_source=miragenews&utm_medium=miragenews&utm_campaign=news [Accessed on May 19, 2024].
[9] Mussagy, CU. (2022). Ionic liquids or eutectic solvents? Identifying the best solvents for the extraction of astaxanthin and β-carotene from Phaffia rhodozyma yeast and preparation of biodegradable films. Green Chemistry. doi.org/10.1039/D1GC03521E
[10] Shellworks (2022). Why are pigments problematic for the planet? [Online]. Shellworks. Available at: https://shellworks.com/why-are-pigments-problematic-for-the-planet/#:~:text=Not%20only%20are%20pigments%20extremely,toxicity%20and%20inability%20to%20biodegrade. [Accessed on May 21, 2024].
[11] European Coatings (2024). Pigments could act as sustainable power sources. [Online] European Coatings. Available at: https://www.european-coatings.com/news/markets-companies/interview-pigments-could-act-as-sustainable-power-sources/ [Accessed on May 21, 2024].
[12] Jekal, S., et al. (2024). Designing Novel LiDAR-Detectable Plate-Type Materials: Synthesis, Chemistry, and Practical Application for Autonomous Working Environment. ACS Applied Materials & Interfaces. doi.org/10.1021/acsami.4c00470