Graphene and Nanotube Coating Turns Ordinary PET Fibres into Conductive, Temperature-Sensing Textiles

Researchers in China have developed a way to transform ordinary polyester fibres into electrically conductive, temperature-sensitive textiles by coating them with a carefully engineered layer of graphene oxide and carbon nanotubes. The work, published in the Journal of Materials Science, addresses one of the most stubborn obstacles in the field of conductive polymer composites: getting carbon nanomaterials to stick together, stay dispersed, and form continuous electrical pathways without wrecking the mechanical properties of the underlying fibre. The team, led by Wenguang Yu and colleagues at Zhejiang Jiaren New Materials and Nanjing Tech University, reports fibres that are not only conductive but also ten percent stronger than unmodified polyester, a combination that has proven remarkably difficult to achieve.

The substrate at the heart of the study is polyethylene terephthalate, or PET, the ubiquitous polymer found in drink bottles and clothing alike. PET is cheap, tough, and easy to melt-spin into fibre, but it is an electrical insulator and interacts poorly with carbon-based nanofillers. To overcome this, the researchers turned to a hybrid fibre strategy, blending PET with a thermotropic liquid crystal polyester, or TLCP, a polymer whose rod-like chains spontaneously orient themselves during melt spinning. This self-orientation is more than a curiosity; it creates a more ordered internal structure that gives the composite fibre enhanced stiffness and strength, and it provides a more compatible surface for subsequent nanomaterial deposition.

The interfacial chemistry is where the new work makes its most distinctive contribution. Graphene oxide, the oxidised form of graphene, carries oxygen-containing functional groups that make it dispersible in water and reactive toward polymers, but raw graphene oxide still bonds weakly to PET. The team therefore employed functionalised graphene oxide, chemically modified to improve its compatibility with the polyester matrix, and drew on earlier findings from their own group showing that polyketone, a polymer with a highly polar carbonyl-rich backbone, can act as a compatibiliser between PET and carbon nanomaterials. By anchoring the nanofillers through these polyketone-assisted interactions, the researchers reduced the agglomeration and interfacial slippage that typically plague carbon-nanomaterial-reinforced polymer composites.

The coating process itself is a two-stage impregnation of the finished PET/TLCP fibres. First, the fibres are soaked in a dispersion of large-lateral-sized graphene oxide, abbreviated LGO, whose broad nanosheets are hundreds of nanometres to micrometres across. Under ultrasonic agitation, these large sheets wrap around the fibre and assemble into a highly oriented coating framework aligned along the fibre axis. The ultrasonic treatment serves a dual purpose: it drives the nanosheets into intimate contact with the fibre surface and encourages them to lie flat and parallel, maximising the overlap between adjacent sheets, which is essential for electron transport.

Large sheets alone, however, leave gaps. Where one LGO nanosheet ends, a discontinuity in the conductive network appears, and electrons must find a way across. This is where the second stage of the coating comes in. The researchers followed the LGO treatment with an impregnation of small-lateral-sized graphene oxide, or SGO, together with carbon nanotubes. The smaller nanosheets and the high-aspect-ratio nanotubes infiltrate the interstitial spaces between the large LGO sheets, bridging the gaps and stitching the coating into a densely packed, continuous architecture. The result is a hierarchical structure reminiscent of brick-and-mortar masonry: large plates provide the primary load-bearing and conducting framework, while smaller fillers act as the mortar that seals the seams.

The electrical performance of these hierarchical coatings proved highly sensitive to processing conditions, and the team systematically optimised them. When the LGO impregnation concentration was set at 2 milligrams per millilitre and the SGO concentration at 3 milligrams per millilitre, with an ultrasonic impregnation time of just five minutes, the resistivity of the composite fibres dropped to a minimum of 2.3 times ten to the third ohm centimetres. That figure represents a dramatic drop from the essentially insulating character of pristine PET and demonstrates that a percolating conductive network can be established on the fibre surface with remarkably modest nanomaterial loadings and a short, industrially plausible treatment time.

Just as importantly, the coating did not come at the expense of mechanical integrity, which is the usual trade-off in conductive textile research. The treated fibres achieved a tensile strength of 560 megapascals, ten percent higher than that of pure PET fibres. The authors attribute this gain to the synergy between the oriented TLCP phase inside the fibre and the interfacial interactions between the carbon nanomaterials and the polymer groups on the fibre surface. Rather than acting as a brittle overlayer prone to cracking and delamination, the graphene-based coating appears to reinforce the fibre, transferring stress across a well-bonded interface. For wearable applications, where fibres are repeatedly bent, stretched, and abraded, this combination of conductivity and strength is essential.

Perhaps the most intriguing property of the new fibres is their temperature sensitivity. Because the electrical resistance of the coating changes measurably with temperature, the fibres function as built-in thermal sensors. The team measured a temperature sensitivity of minus 0.66 percent per degree Celsius, meaning the fibre’s resistance decreases in a consistent, quantifiable way as temperature rises. This behaviour arises from the interactions between the carbon nanomaterials and the PET molecular groups, which modulate electron transport through the coating as thermal energy changes the spacing and contact quality between nanosheets and nanotubes. A stable, linear response of this kind is exactly what flexible temperature-sensing devices require, and it opens the door to smart garments that can monitor skin temperature, detect overheating in protective clothing, or provide feedback in human-machine interfaces.

The broader context of this research is the surging demand for flexible, wearable electronics and smart textiles. Conventional approaches to conductive fabrics, such as coating textiles with metals or intrinsically conductive polymers, often suffer from poor durability, high cost, or limited processability. Carbon nanomaterials offer an attractive alternative because they are lightweight, chemically robust, and mechanically strong, but their tendency to clump and their weak adhesion to polymer surfaces have limited real-world deployment. The strategy demonstrated here, combining functionalised nanofillers, a polyketone compatibiliser, and a size-segregated two-step coating, offers a template for solving both the dispersion problem and the interfacial problem in a single, scalable process built around standard fibre impregnation equipment.

The work also builds on a coherent line of earlier studies by the same group, which previously showed that graphene oxide of varying lateral size can strengthen PET fibres and that functional one-dimensional and two-dimensional carbon nanomaterials can synergistically enhance the interfaces of PET/TLCP fibres. The new results extend that programme from mechanical reinforcement to full electrical functionality, and they arrive at a moment when the recycling and high-value reuse of waste polyester textiles has become a pressing industrial priority; the study itself was supported by a project on closed-loop recycling and high-value utilisation of waste polyester textiles. If the coating approach can be scaled from laboratory impregnation baths to continuous textile finishing lines, the humble polyester fibre, already the workhorse of the global textile industry, could gain a second career as the sensing backbone of the wearable electronics revolution, conducting electricity, bearing load, and feeling the heat all at once.

Subject of Research: Polyketone-assisted graphene oxide and carbon nanotube surface coatings for conductive, temperature-sensitive PET/TLCP composite fibres

Article Title: Polyketone-assisted oxide graphene/carbon nanotube surface coating to fabricate conductive PET/TLCP composite fibres

Article References: Yu, W., Li, H., Wang, T., Chu, S., Mao, Z., Liu, H., & Guan, J. (2026). Polyketone-assisted oxide graphene/carbon nanotube surface coating to fabricate conductive PET/TLCP composite fibres. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13916-0

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13916-0

Keywords: graphene oxide, carbon nanotubes, PET fibres, TLCP, polyketone, conductive composites, nanocomposites, smart textiles, temperature sensing, wearable electronics, surface coating, interfacial compatibility