Electrospinner: Interface modulation strategy to construct graphene/pure cotton composite yarn: good conductivity, strength and toughness, heating and sensing!

Background

Graphene composite yarn has excellent conductivity, mechanical properties, flexibility and light weight, and shows great application potential in multifunctional wearable electronic devices. However, the performance of graphene composite yarn is limited by the weak interface interaction between fiber and graphene. Therefore, how to give pure cotton yarn high conductivity while maintaining the inherent properties of pure cotton yarn is the most challenging problem!

Recently, the team of Professor Bai Yongxiao of Lanzhou University published a research progress entitled "Interfacial Modulation of Polydopamine-Reduced Graphene Oxide for Achieving Highly Conductive and Strong Graphene/Cotton Composite Yarn Toward Smart Wearable Devices" in Advanced Fiber Materials, systematically summarizing a polydopamine-reduced graphene oxide (PDA-RGO) interface modulation strategy, using PDA-RGO as an interface connecting molecule to form hydrogen bonds with pure cotton yarn (CY); at the same time, the functionalized interface forms a π-π interaction with highly conductive graphene, and a graphene-coated pure cotton yarn with high conductivity and high strength is prepared. This conductive yarn can be used in low-voltage flexible wearable heaters and high-sensitivity pressure sensors, showing great application potential in the field of high-performance multifunctional electronic fabrics.

The main point of this paper

First, highly conductive graphene was modified on the surface of pure cotton yarn by electrospinning and impregnation. The preparation process includes:

(1) self-assembly of graphene oxide on the surface of CY;

(2) construction of PDA-RGO interface layer;

(3) cross-linking of highly conductive graphene.

As shown in Figure 1, the PDA-RGO interface layer not only promotes the effective deposition of highly conductive graphene nanosheets on the fiber surface, but also realizes the orderly arrangement of graphene nanosheets between the fiber gaps. The structural characterization of SGCY composite yarn is shown in Figure 2.

Secondly, the effect of PDA-RGO as an interface connecting molecule on the conductivity and tensile strength of the composite yarn was evaluated, and the results are shown in Figure 3. CY material has good electrical insulation. Using PDA as an interface connecting molecule, the average conductivity of G/PDA/CY and ST/G/PDA/CY is (19.78±1.85) S/m and (28.94±3.26) S/m, respectively. Using GO as an interface material can significantly improve the conductivity of G/GO/CY to (135.71±6.18) S/m. It is worth noting that using PDA-RGO as an interface connecting molecule, the average conductivity of SGCY can reach (856.27±7.02) S/m (i.e., an average resistance of 57.57±5.35 Ω), which is mainly attributed to the large specific surface area of ​​the PDA-RGO interface layer, which can assist the graphene nanosheets to be arranged radially along the fiber; at the same time, RGO and graphene work together to establish a conductive channel to achieve high conductivity of the composite yarn. In addition, the interface layer forms a strong hydrogen bond network, which absorbs a large amount of fracture energy during stretching, so that the tensile strength of the SGCY composite yarn is increased to (172.03±8.03) MPa, achieving improved mechanical properties.

Finally, thanks to the excellent conductivity, tensile strength and biocompatibility of the graphene/pure cotton composite conductive yarn, the steady-state temperature of SGCY can reach (50±1.5)℃ at a low voltage of 3V, and it has good flexibility, stability and weather resistance. SGCY is integrated with a cotton fabric substrate to prepare a flexible wearable heater that can be attached to different parts of the human body (such as the index finger, waist, and knee) for heating human joints (Figure 4).

Human health can be evaluated through various physiological parameters, and wearable electronic fabric sensors can be in direct contact with the skin, thereby realizing real-time monitoring of human physiological parameters. Thanks to the excellent conductivity of SGCY, SGCY warp and weft weaving into pure cotton fabric can be used as a flexible wearable pressure sensor. As shown in Figure 5, the pressure sensor based on SGCY exhibits high sensitivity (S1=33.03 kPa-1), fast response/recovery time (77.4±9 ms/43±4.5 ms), and wide detection range. It can effectively sense and detect tiny stimulation signals of the human body, such as pulse beating, vocal cord vibration, facial muscle movement, etc., laying the foundation for the development of flexible wearable electronic fabrics.

In summary, graphene/pure cotton composite conductive yarn was prepared by electrospinning using the PDA-RGO interface modulation strategy. The prepared SGCY conductive yarn has a conductivity of (856.27±7.02) S/m and a tensile strength of (172.03±8.03) MPa, which is 1.59 times that of pure cotton yarn. The constructed graphene/pure cotton composite conductive yarn can be used in flexible wearable heaters and pressure sensors, and has great application potential in the field of wearable smart fabrics.

Electrospinning Nanofibers Article Source:

https://link.springer.com/article/10.1007/s42765-024-00449-x