From pump seals to ship hulls and medical devices, a review asks how far nanoscale design can take protective coatings.
Paper: Recent works in the area of nanoscience and nanotechnology for coatings application - a review. AI-generated abstract conceptual image created using ChatGPT/OpenAI
In a recent review article published in the journal Academia Nano: Science, Materials, Technology, researchers survey studies and industrial applications of nanoscience and nanotechnology in surface coatings, focusing on protection and function. Both authors work for Berger Paints India Ltd.; they state that the company had no role in the design or writing of the review.
Nanoscience changes coatings
For centuries, coatings have served to protect and adorn surfaces. The advent of nanoscience has expanded the capabilities of these materials. When dimensions shrink below approximately 100 nanometers, materials can exhibit different properties because of high surface-to-volume ratios and quantum effects.
This allows formulators to tune characteristics such as hardness, barrier resistance, optical response, and antimicrobial activity, often at much lower loadings than conventional additives.
From an industrial viewpoint, this means formulations may gain performance without compromising rheology (how the coating flows), appearance, or cost, opening up possibilities for specialty finishes.
Key nano-coating applications
One of the most extensively explored areas is the use of nanoscale fillers for mechanical reinforcement. Polymer coatings, while economical and easy to apply, can lack hardness, load-bearing capacity, and wear resistance.
Nanofillers, categorized by dimensionality (0D nanoparticles, 1D nanorods/nanotubes, 2D layered materials like graphene and MXenes (thin sheets containing metal atoms), and 3D nanohybrids combining different filler types), address these limitations. The binder largely determines adhesion; nanofillers mainly change surface and interfacial properties.
Zero-dimensional nanoparticles such as nano-SiO2 and carbon black increase hardness and distribute stress more evenly, while higher-aspect-ratio fillers such as carbon nanotubes improve load transfer and reduce friction.
Two-dimensional materials, such as graphene and MXenes, can reduce wear rates, especially when combined in hybrid systems. A critical challenge remains the reproducible dispersion of these fillers, as agglomeration can undermine their benefits.
Beyond particle fillers, polyhedral oligomeric silsesquioxane (POSS) is a distinct molecular approach to multifunctional coatings. Unlike conventional particulate nanofillers, POSS molecules are organic–inorganic hybrids, typically 1–3 nm in size, that behave as the smallest possible silica “particles” and disperse at the molecular level.
This characteristic sidesteps much of the agglomeration problem common with 0D fillers. The organic groups at its vertices allow POSS to be integrated into polymers through blending, grafting, or cross-linking, supporting hard yet flexible, icephobic, anticorrosive, fire-retardant, and self-healing coatings.
Researchers are testing antimicrobial and antifouling nanomaterials in healthcare, marine, and consumer applications. Nanoparticles of silver, copper, gold, and zinc oxide predominate in this category.
Silver, for instance, has broad biocidal activity, while zinc oxide inhibits Staphylococcus aureus. Titanium dioxide, with its photocatalytic action (reactions triggered by light), offers UV-driven biocidal effects and self-cleaning capabilities.
In marine environments, these nanomaterials are engineered to control biocide delivery, thereby mitigating biofouling by inhibiting the initial bacterial colonization that precedes macrofouling (the settlement of algae and barnacles). In one field test, copper-oxide nanocontainers loaded with other biocides kept hull sections free of fouling for a year. In a separate study, mesoporous silica nanocapsules with a silver outer layer showed improved early antifouling performance and were reported to reduce environmental impact compared with free biocides.
In medical devices, silver-functionalized catheters show activity against Staphylococcus aureus, and chitosan-silver nanocomposites on dental implants reduce bacterial adhesion and biofilm formation. The review does not report whether these coatings prevent infections in patients. The primary hurdle is demonstrating a consistent rate of antimicrobial ion release over the device’s lifetime for reproducible efficacy.
The review then turns to structural color systems, which offer a pigment-free alternative to traditional coloration. Structural color arises from the interaction of light with precisely engineered periodic nanostructures, a phenomenon observed in nature (e.g., peacock feathers). This color does not rely on dyes that can bleach. Viewing angle affects some finishes; automotive performance claims need independent testing.
Industrial nano-coating challenges
Laboratory demonstrations of nano-enabled coating functionalities are abundant, but the article emphasizes that the main challenges lie in successful industrial deployment.
Key barriers include the reproducibility of nanomaterial dispersion in large batches, as lab-scale methods often fail to transfer to ton-scale production, leading to agglomeration and diminished performance.
The durability of these advanced functions under real-world conditions, including UV exposure, abrasion, and chemical attack over extended periods, also requires stronger validation than idealized tests can provide.
The authors examine environmental, health, and safety (EHS) concerns, particularly regarding the potential toxicity of free nanoparticles and the lack of a dedicated international standard for their use in coatings. EU REACH already sets registration and characterization obligations for nanoforms. To address these concerns, the review advocates for benign-by-design chemistries, encapsulation of nanophases to limit the release of free particles, and life-cycle assessments.
Cost remains a barrier, as high-purity nanomaterials and specialized processing command a premium, creating demand for cheaper feedstocks and low-loading formulations to compete on price.
The absence of harmonized, coating-level performance standards also complicates fair comparisons and slows approvals.
From laboratory results to commercial coatings
Nanoscience has opened up a new design space for the coatings industry. The structure–property relationships governing nanoscale fillers, molecular hybrids such as POSS, antimicrobial agents, and structural color systems are well understood enough to guide the design of specific functions. Many nanoadditives work at low loadings.
Commercial readiness varies. Common 0D particles are used in primers and topcoats, and ultrananocrystalline diamond wear coatings are already used in pump seals and bearings. Diamond coatings require costly deposition processes and are generally suited to rigid substrates; polymer coatings remain practical for large areas. 3D hybrid fillers remain in research or early pilots; evidence for self-assembling structural color comes partly from developers and automotive trials, which need independent verification.
Reproducible dispersion, field-validated durability, compliance with EHS regulations, lower costs, and standardized coating-level tests could help more of these coatings deliver consistent performance across production batches and years in service.