It is with great pleasure that we introduce this special issue of Plasma Processes and Polymers devoted to the use of plasmas for the synthesis of nanoparticles and nanocomposite coatings. There are 10 papers in this special issue discussing advances in the processing science of nanomaterials, in their use as functional and structural materials, and providing a comprehensive review on the use of plasmas as additive manufacturing tools. Overall, these contributions clearly suggest that this field is on a rapid growth trajectory. The range of materials that are compatible with plasma reactors is expanding, plasma‐produced nanomaterials are being evaluated for a continuously broader range of applications, and many research groups have made and are poised to continue making significant scientific contributions. These are being enabled by the uniqueness of plasma‐based processes. This is remarkable, considering that nanoparticles were originally viewed by the plasma community as an undesired contaminant.^[1^] The original impetus for the study of nanoparticles in plasmas came from early reports of dust nucleation and growth in the low‐pressure plasma reactors used by the semiconductor industry. The subsequent studies, focused on the detection of nanoparticles in plasmas and on the modeling of plasma‐driven nucleation chemistry, suggested that plasmas can be desirable sources of nanoparticles.^[2^] As a consequence, plasma reactors have been redesigned not to prevent nanoparticle formation, but to deliberately produce useful nanomaterials.^[3^]

The manuscripts in this special issue clearly suggest that this subfield of plasma science has plenty of room for innovation and creative advances. In particular, the use of plasma‐produced materials in the polymer‐based composite is attracting a lot of attention. Juangsa et al.^[4^] describe the thermal transport properties of nanocomposite realized by dispersing plasma‐produced silicon nanoparticles into a polystyrene matrix. This approach is relevant for potential applications in thermoelectric devices. It is interesting to point out that a very similar approach has been proposed by Liu et al.^[5^] for the realization of hybrid photovoltaic devices in which silicon nanoparticles are dispersed in a poly(3‐hexylthiophene) matrix. Bonde et al.^[6^] provide a detailed study of the capability of plasma‐produced copper clusters to disperse within a poly(methyl methacrylate) matrix. Particularly intriguing is the contribution from Nakahara et al.,^[7^] which discusses the mechanical properties of polymers reinforced using microwave plasma‐produced graphene snowflakes. The capability of the microwave plasma to provide free‐standing, single‐to‐few layers graphene is crucial in this study.^[8^] This is one of the very few studies discussing the mechanical properties of materials that are either realized via a plasma process or reinforced using plasma‐produced additives. As a comparison, the vast majority of the community is currently focusing on functional materials. Structural applications represent therefore an untapped area of growth. Pleskunov et al.^[9^] describe the use of a plasma‐based process not to disperse inorganic particles into an organic matrix, but to disperse polyacrylic acid particles into a poly(ethylene oxide) thin film, with potential application for protein immobilization. Finally, Sui et al.^[10^] provide a comprehensive review of the use of plasma for additive manufacturing, with a focus on the use of low‐temperature plasmas to drive the nucleation and growth of particles within a polymer‐based matrix. This contribution highlights the many promising reports in this area, suggesting that atmospheric pressure plasmas will play a critical role in the realization of many flexible electron devices.

Another contribution that describes the realization of nanocomposites is the one from Beaudette et al.^[11^] In this expert opinion, the authors highlight how a low‐temperature plasma source can be used to realize dense films of zinc oxide nanoparticles (via aerodynamic impaction), and how this can then be postprocessed via atomic layer deposition to infill the nanoparticle film with a second inorganic material, such as titanium nitride. Aside from the promising electrical transport properties, this approach is inherently versatile and flexible, opening the doors to many different heterostructures with several potential technological applications.

The manuscripts from Dasgupta et al., Uner et al., and Haq et al. focus on the synthesis and processing of free‐standing nanoparticles. Haq et al.^[12^] describe the synthesis of silicon carbide nanocrystals in an atmospheric pressure microplasma, confirming the capability of these reactors to process refractory materials like nitrides and carbides despite operating at relatively low‐temperature and using short reaction times.^[13^] Dasgupta et al.^[14^] describe a process for the synthesis and inline coating of silicon particles with an oxide shell. This confirms the capability of plasma processes to realize core‐shell structures and to ultimately control surfaces, which is absolutely crucial for tuning the material functionality. Uner et al.^[15^] describe a highly novel approach to nanoparticle synthesis in plasmas: instead of supplying chemical precursors to the reactor, the authors supply two separate but intimately mixed aerosols of gallium and antimony to a low‐temperature radiofrequency plasma, resulting in the formation of high‐quality gallium antimonide nanoparticles. This approach is referred to by the aerosol community as aerotaxy, and the manuscript from Uner et al. represents one of the first demonstrations of its use in conjunction with a plasma processor.

Finally, the contribution from Trad et al.16 describes the synthesis of cobalt–nickel intermetallic particles using nanosecond pulsed discharges in liquid nitrogen. The formation and properties of plasmas in contact with liquids is a rapidly expanding field in plasma science, and this report confirms that this approach can also provide new materials synthesis pathways.

Overall, the manuscripts in this special issue indicate that the plasma processing science of nanomaterials is a field that is at the same time mature and exciting. Novel reactor designs are still being proposed, and new material combinations are still being demonstrated. The uniqueness of low‐temperature plasmas in their capability of establishing a nonequilibrium processing environment is the crucial enabling factor, clearly setting them aside from other nanoparticle production techniques. We thank the authors for their contributions and anxiously look forwards to future developments in this field.

我们非常高兴地介绍本期《等离子工艺和聚合物》致力于使用等离子体合成纳米颗粒和纳米复合涂层。在本期特刊中，有10篇论文讨论了纳米材料加工科学的进展，将其用作功能材料和结构材料，并对使用等离子体作为增材制造工具进行了全面综述。总体而言，这些贡献清楚地表明该领域正处于快速增长的轨道上。与等离子体反应器兼容的材料范围不断扩大，正在对等离子体生产的纳米材料进行评估，以使其应用范围不断扩大，许多研究小组已经做出并准备继续做出重要的科学贡献。基于等离子工艺的独特性使这些成为可能。这很了不起^[ 1 ^]等离子体中纳米颗粒研究的最初动力来自半导体行业使用的低压等离子体反应器中粉尘成核和生长的早期报道。随后的研究集中在血浆中纳米颗粒的检测和等离子体驱动的成核化学的建模上，这些研究表明血浆可能是纳米颗粒的理想来源。^[ 2 ^]结果，已经对等离子体反应器进行了重新设计，以防止纳米颗粒的形成，而不是故意制造有用的纳米材料。^[ 3 ^]

本期特刊的稿件清楚地表明，等离子体科学的这一子领域具有很大的创新和创造空间。特别是，在聚合物基复合材料中使用等离子产生的材料引起了很多关注。Juangsa等。^[ 4 ^]描述了通过将等离子体产生的硅纳米颗粒分散到聚苯乙烯基体中实现的纳米复合材料的热传输特性。该方法与热电设备中的潜在应用有关。有趣的是，Liu等人提出了一种非常相似的方法。^[ 5 ^]用于实现将硅纳米颗粒分散在聚（3-己基噻吩）基质中的混合光伏设备。邦德等。^[ 6 ^]提供了对等离子体产生的铜簇在聚（甲基丙烯酸甲酯）基质中分散的能力的详细研究。Nakahara等人^[ 7 ^]的贡献尤其令人着迷，它讨论了使用微波等离子体产生的石墨烯雪花增强的聚合物的机械性能。微波等离子体提供独立的，很少见的石墨烯层的能力在这项研究中至关重要。^[ 8 ^]这是为数不多的讨论材料力学性能的研究之一，这些材料要么通过等离子工艺实现，要么使用等离子产生的添加剂增强。相比之下，社区中的绝大多数人目前都集中在功能材料上。因此，结构应用代表了尚未开发的增长领域。Pleskunov等。^[ 9 ^]描述了基于等离子体的过程，不是将无机颗粒分散到有机基质中，而是将聚丙烯酸颗粒分散到聚环氧乙烷薄膜中，具有潜在的蛋白质固定化应用。最后，隋等。^[ 10 ^]全面介绍了等离子体在增材制造中的使用，重点是利用低温等离子体驱动聚合物基体中颗粒的形核和生长。这一贡献突出了该领域的许多有希望的报告，表明大气压等离子体将在实现许多柔性电子器件中发挥关键作用。

Beaudette等人的另一种描述纳米复合材料实现的贡献。^[ 11 ^]在这一专家意见中，作者强调了如何使用低温等离子体源实现氧化锌纳米颗粒的致密膜（通过空气动力学撞击），然后如何通过原子层沉积对其进行后处理以填充纳米颗粒具有第二无机材料（例如氮化钛）的薄膜。除了有希望的电传输特性外，这种方法本身具有通用性和灵活性，为具有多种潜在技术应用的许多不同异质结构打开了大门。

Dasgupta等人，Uner等人和Haq等人的手稿。专注于独立式纳米颗粒的合成和加工。Haq等。^[ 12 ^]描述了在大气压微等离子体中合成碳化硅纳米晶体，证实了这些反应器尽管在相对较低的温度下运行且使用了较短的反应时间，但仍能够处理诸如氮化物和碳化物等难熔材料。^[ 13 ^] Dasgupta等。^[ 14 ^]美国专利No.5,775,855描述了用氧化物壳合成和在线涂覆硅颗粒的方法。这证实了等离子工艺实现核-壳结构并最终控制表面的能力，这对于调整材料功能至关重要。Uner等。^[ 15 ^]描述了一种用于等离子体中纳米颗粒合成的新颖方法：作者没有向反应堆提供化学前驱物，而是向低温射频等离子体提供了两种单独的但紧密混合的镓和锑气雾剂，从而形成了高质量的镓锑纳米颗粒。这种方法被气溶胶界称为航空学，而Uner等人的手稿则称为“航空学”。代表其与等离子处理器结合使用的首批演示之一。

最后，Trad等人的贡献。图16描述了使用液氮中的纳秒脉冲放电合成钴-镍金属间化合物。与液体接触的等离子体的形成和性质是等离子体科学中一个迅速扩展的领域，该报告证实该方法还可提供新的材料合成途径。

总体而言，本期特刊的手稿表明，纳米材料的等离子体处理科学是一个既成熟又令人兴奋的领域。仍在提出新颖的反应堆设计，并且仍在展示新的材料组合。低温等离子体在建立非平衡处理环境方面的独特性是关键的使能因素，显然将其与其他纳米颗粒生产技术区分开来。我们感谢作者的贡献，并热切期待该领域的未来发展。