The study, published in Advanced Composites and Hybrid Materials, was led by Hui Gao, Yunli Wang, Ke Pei, and Weilin Xu, with colleagues at Wuhan Textile University and Hubei University. The researchers describe a hierarchical, bioinspired assembly process that builds up color and protection on basalt fiber fabrics in three deliberate stages. First, silk fibroin, the protein extracted from silkworm cocoons, is converted into nanoparticles and deposited onto the fiber surface. Then the coated fabric is dyed with an acid dye in an ethanol-water mixture. Finally, a thin layer of polydimethylsiloxane, a flexible silicone polymer, is cured onto the surface at high temperature, sealing the color system beneath a hydrophobic armor. The resulting material, which the team abbreviates PDBS, combines vivid coloration with remarkable resistance to thermal shock and ultraviolet radiation.

The choice of silk fibroin as an intermediate layer is the conceptual heart of the work. Silk proteins are famous for their mechanical toughness and their ability to self-assemble into ordered structures, and materials scientists have increasingly looked to silk as a sustainable building block for functional coatings. In this study, the researchers used a technique called non-solvent induced phase separation to force dissolved silk fibroin out of solution and into discrete nanoparticles. When the conditions are tuned correctly, these nanoparticles deposit uniformly onto the basalt fiber surface, creating a protein-rich layer that is far more receptive to dyes than the bare, chemically inert glass. The layer essentially gives the volcanic fiber a biopolymer skin that behaves like the protein fibers found in conventional textiles.

Getting that deposition right required careful optimization. The team found that the concentration of silk fibroin in the processing solution played a decisive role in how well the nanoparticles adhered to the basalt fibers. At a concentration of 60 percent by weight, the deposition reached its optimum, producing a coating dense and uniform enough to anchor the subsequent dye chemistry. Below that level, the protein layer was too sparse to provide adequate binding sites; above it, the solution properties apparently worked against clean, even deposition. This kind of concentration-dependent behavior is typical of phase separation processes, where the balance between nucleation, growth, and aggregation of the polymer determines the final morphology of the coating.

With the silk nanoparticle layer in place, the researchers turned to coloration. Acid dyes are water-soluble anionic dyes that bind strongly to protein fibers through ionic interactions, which is why they are the standard choice for wool and silk textiles. Basalt fibers, being essentially mineral glass, offer no such binding chemistry, but the silk fibroin coating restores it. The team carried out the dyeing in an ethanol-water system and systematically varied the ethanol content, discovering that color strength peaked when the solvent mixture reached 98 percent ethanol. The ethanol-rich environment appears to promote dye uptake and fixation on the nanoparticle layer, driving the coloration toward its maximum intensity. The result is a fabric whose color is not a superficial paint job but a chemically anchored dye-protein system integrated into the fiber assembly.

Color alone, however, would not survive the environments the researchers had in mind. Spacecraft exteriors and astronaut textiles face vacuum, intense ultraviolet bombardment, and temperature swings that would destroy most conventional dye systems. To protect the coloration, the team applied a polydimethylsiloxane coating and cured it at high temperature. Polydimethylsiloxane, usually abbreviated PDMS, is a silicone elastomer renowned for its thermal stability, chemical inertness, optical clarity, and low surface energy. Cured as a thin film over the dyed fabric, it acts as a transparent shield: light passes through to reveal the vivid color beneath, while the polymer blocks moisture, moderates ultraviolet exposure, and cushions the underlying layers against mechanical and thermal stress.

The hydrophobic character imparted by the PDMS layer is one of the study’s most practically significant outcomes. After surface functionalization, the water contact angle of the samples reached approximately 120 degrees, a value well into the hydrophobic regime. Water beads on the surface rather than spreading, which limits moisture absorption, reduces contamination, and helps the fabric shed liquids in humid or wet conditions. For aerospace applications, where condensation, coolant leaks, or exposure to precipitation can compromise materials, this self-shedding quality adds a layer of robustness that goes hand in hand with the color protection. The combination of hydrophobicity and dye durability in a single treatment is what elevates the work from a coloration study to a genuine multifunctional materials advance.

The most striking evidence for the system’s resilience came from extreme environmental testing. The researchers subjected the PDMS-coated, dyed basalt fabric with silk fibroin nanoparticles to repeated cycles between 150 degrees Celsius and minus 196 degrees Celsius, the latter being the boiling point of liquid nitrogen. Such cycling imposes enormous thermal stress, because the components of a composite expand and contract at different rates, and brittle coatings tend to crack or delaminate under repeated shock. The PDBS fabric retained both its vivid coloration and its structural integrity through these cycles. It also withstood intense ultraviolet irradiation, the kind of exposure that in low Earth orbit bleaches and degrades most organic colorants within a short time. The team attributes this durability to the synergy of the three-layer architecture: the protein nanoparticles anchor the dye, and the silicone overlayer protects the whole assembly.

The authors point to a range of potential aerospace applications for the material. Deep-space exploration missions require components and surfaces that can be visually identified and distinguished, whether for assembly, inspection, or scientific marking, and a fabric that stays colorful under radiation and thermal cycling could serve as identification material on spacecraft. Protective textiles for astronauts could benefit from the same combination of visual function and environmental resistance, and flexible spacecraft coverings, such as thermal blankets or deployable structures, could incorporate the colored basalt fabric where both durability and visibility matter. Beyond aerospace, the researchers suggest the strategy could extend to other high-technology sectors where extreme conditions rule out conventional coloration methods.

The work also carries a broader lesson about bioinspired materials design. Rather than treating basalt fiber’s inertness as a flaw to be overcome with harsh chemical treatments, the team layered natural protein chemistry on top of the mineral surface, borrowing the dye-binding behavior that silkworm silk offers naturally, and then finished the assembly with a synthetic polymer chosen for its own extreme-environment credentials. The hierarchical structure, protein nanoparticles beneath dye beneath silicone, mirrors the way biological materials often combine soft and hard components at multiple scales to achieve properties no single layer could deliver. Funded by the National Natural Science Foundation of China and the Key Research and Development Program of Hubei Province, the study offers a template that other researchers may adapt to other inert reinforcements, other biopolymer intermediates, and other protective overlayers, potentially widening the palette of materials available to engineers who design for the harshest environments imaginable.

Subject of Research: Bioinspired coloration and environmental protection of basalt fiber composites using silk fibroin nanoparticles and PDMS coatings

Article Title: Bioinspired hierarchical assembly of silk fibroin nanoparticles and PDMS on basalt fibers for vivid coloration and extreme environment resistance in aerospace composites

Article References: Gao, H., Liu, S., Lei, Z., Cao, G., Sheng, D., Xiao, X., Zhang, Q., Jin, W., Wang, Y., Pei, K., & Xu, W. (2026). Bioinspired hierarchical assembly of silk fibroin nanoparticles and PDMS on basalt fibers for vivid coloration and extreme environment resistance in aerospace composites. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02062-5

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02062-5

Keywords: basalt fiber, silk fibroin, PDMS, aerospace composites, hydrophobicity, acid dyeing, nanoparticles, extreme environment resistance, ultraviolet radiation, thermal cycling, bioinspired materials, textile engineering