Abstract: Graphene, as a new type of two-dimensional carbon nanomaterial, has emerged as a prominent research focus in recent years due to its unique composition and excellent conductivity, thermal conductivity, and mechanical properties. The graphene fiber, a novel carbon-based fiber crafted from graphene layers, inherits the advantages of graphene, such as lightweight and flexibility. In many practical applications, balancing the multiple properties of graphene fibers can be challenging, and it is necessary to choose a suitable spinning method to regulate the chemical composition and structure of graphene fibers and polymers, so as to broaden the application field of graphene-based fibers. 
Polyacrylonitrile is a synthetic fiber with good elasticity and weather resistance. It can be used in industrial production through wet spinning and can be combined with graphene incorporation to obtain high-performance composite fibers. Microfluidic spinning technology is a new type of spinning technology developed on the basis of microfluidic chip technology, which is combined with wet spinning technology to build a microfluidic wet spinning system. Microfluidic chip technology enables precise control over the microstructure of spinning solutions and is characterized by a high degree of miniaturization, integration, and cost-effectiveness. This article utilizes microfluidic wet spinning technology to prepare a novel type of conductive fiber with a core-sheath structure. By precisely adjusting the spinning fluid inside the microfluidic chip spinning channel, the spinning fluid exhibits laminar flow characteristics in the microchannel. Through a simple process, the directional control of graphene in the fiber outer layer is achieved, fully utilizing the high conductivity and high specific surface area of the outer layer material, as well as the mechanical properties of the core layer polyacrylonitrile fiber. As the flow rate of the composite fiber layer increases, the arrangement of graphene in the fiber layer gradually becomes standardized under shear stress and compression in the microfluidic chip channel, forming a continuous conductive path.
The article studied the morphology, mechanical properties, and electrical properties of skin core fibers. In SEM images and stress-strain curves, compared with pure polyacrylonitrile fibers, the diameter and strength of composite fibers showed a trend of first increasing and then decreasing with the increase of skin solution. The resistance of core-sheath composite fibers decreased and the conductivity increased. When the skin flow rate reached a certain value, due to the aggregation of graphene in microchannels, the conductivity of the composite fibers decreased, and their mechanical properties also declined. It could be found that by applying different voltages at both ends of the composite fiber to test the electrical heating performance of the composite fiber, the highest temperature reached by the fiber and the heating rate per second vary under different voltages. The higher the voltage applied at both ends of the fiber, the greater the maximum temperature reached and the heating rate also increases. The test shows that the core-sheath fibers had good thermal stability and electrical cycling, and the voltage at both ends of the composite fiber could be quickly heated to the expected temperature.
Functional heating conductive fibers are poised for long-term development in the textile industry, driven by intelligent production processes and technologies. The study of microfluidic wet spinning of graphene and polyacrylonitrile in this article can provide some reference for the development and application of conductive fibers.

Key words: graphene, microfluidics, wet spinning, conductive fibers, electric heating performance

摘要： 石墨烯在纤维中的分布、含量及微观结构等因素影响复合石墨烯导电纤维性能。文章提出以石墨烯为导电基材一步法构筑导电纤维的研究策略，采用微流控湿法纺丝工艺制备石墨烯/聚丙烯腈皮芯结构复合纤维，探究皮层和芯层纺丝液流量对石墨烯取向排列、纤维导电和电热性能影响规律。通过微观形貌观察发现，复合纤维皮层石墨烯取向随着纺丝液流量的变化呈现先增加后减小的趋势，皮层流量为0.10 mL/min时石墨烯取向最佳。高度取向的石墨烯赋予复合纤维优异的力学性能和导电性能，使复合纤维的强度和电导率分别达到241.38 MPa和3.94 S/cm。在4 V电压下，复合纤维表面的温度达到约48.3 ℃，热响应速率为2.0 ℃/s。研究表明通过调控不同的皮芯流量，调整复合纤维的结构和性能，可以成功制备出以石墨烯为基材的复合导电纤维。研究结果可为石墨烯复合加热纤维的开发研究提供参考。

关键词: 石墨烯, 微流控, 湿法纺丝, 导电纤维, 电加热性能