{"title":"导电纳米复合材料的还原光聚合3D打印","authors":"David Tilve-Martinez*, and , Philippe Poulin*, ","doi":"10.1021/accountsmr.5c0006010.1021/accountsmr.5c00060","DOIUrl":null,"url":null,"abstract":"<p >Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymer-based additive manufacturing (AM), driven by the growing demand for multifunctional 3D-printing. While several AM techniques have been adapted to process conductive composites, Digital Light Processing (DLP) stands out for its high-resolution and fast-curing capabilities. However, it poses a central limitation: the requirement for optical transparency in the printing resin, which is compromised by the incorporation of conventional conductive fillers. This Account highlights the advances in overcoming three fundamental challenges in the field: (i) How can conductive nanocomposites be printed by DLP without compromising resolution? (ii) How can high electrical conductivity be achieved at low filler content? (iii) What is the origin of anisotropic conductivity in printed objects, and how can it be mitigated?</p><p >To address the first question, the authors introduced a strategy based on UV-transparent precursors, specifically monolayer graphene oxide (GO). GO’s minimal UV absorption allows its use as a printable nanofiller at weight fractions up to 0.35 vol %, preserving the curing depth and optical clarity required for DLP. Postprinting thermal reduction of GO into reduced graphene oxide (rGO) yields nanocomposites with conductivities up to 10<sup>–2</sup> S m<sup>–1</sup>─comparable to conventional carbon nanotube (CNT) systems but achieved without high UV attenuation. To tackle the second question, the authors explored the use of single-walled carbon nanotubes (SWCNTs), which, due to their high aspect ratio and intrinsic conductivity, exhibit ultralow percolation thresholds (<0.01 vol %). At these concentrations, UV interference is negligible. However, the need for surfactant-assisted dispersion introduces contact resistance, limiting conductivity. To overcome this, this Account presents a hybrid formulation in which GO serves as both dispersant and conductive additive, enhancing internanotube contacts upon reduction. This approach achieves conductivities up to 0.3 S m<sup>–1</sup>, with a total filler content below 0.15 vol %, representing a significant leap in performance without sacrificing resolution. To resolve the third question regarding electrical anisotropy, the study employs polarized Raman spectroscopy, conclusively showing that nanotube alignment is not responsible for the observed directional conductivity differences. Instead, the anisotropy arises from interfacial contact resistance between printed layers, an intrinsic artifact of the layer-by-layer DLP process. Mitigation strategies such as delayed UV curing and temperature-controlled printing were shown to significantly reduce this resistance and improve isotropy.</p><p >Beyond addressing these scientific questions, this Account highlights the practical impact of these materials. Notably, hybrid nanocomposites exhibited strong potential in microwave absorption, reaching broadband reflection losses below −10 dB at low filler loadings, due to combined ohmic and dielectric losses. These outcomes demonstrate that high-resolution, fast DLP printing of conductive materials is not only feasible but also tunable and scalable for applications in sensors, soft robotics, and electromagnetic shielding. By answering these key questions, the work establishes a foundation for the rational design of printable conductive nanocomposites, balancing optical compatibility, conductivity, and mechanical precision─paving the way for next-generation functional devices fabricated through vat photopolymerization.</p>","PeriodicalId":72040,"journal":{"name":"Accounts of materials research","volume":"6 5","pages":"661–671 661–671"},"PeriodicalIF":14.7000,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Vat Photopolymerization 3D Printing of Conductive Nanocomposites\",\"authors\":\"David Tilve-Martinez*, and , Philippe Poulin*, \",\"doi\":\"10.1021/accountsmr.5c0006010.1021/accountsmr.5c00060\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p >Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymer-based additive manufacturing (AM), driven by the growing demand for multifunctional 3D-printing. While several AM techniques have been adapted to process conductive composites, Digital Light Processing (DLP) stands out for its high-resolution and fast-curing capabilities. However, it poses a central limitation: the requirement for optical transparency in the printing resin, which is compromised by the incorporation of conventional conductive fillers. This Account highlights the advances in overcoming three fundamental challenges in the field: (i) How can conductive nanocomposites be printed by DLP without compromising resolution? (ii) How can high electrical conductivity be achieved at low filler content? (iii) What is the origin of anisotropic conductivity in printed objects, and how can it be mitigated?</p><p >To address the first question, the authors introduced a strategy based on UV-transparent precursors, specifically monolayer graphene oxide (GO). GO’s minimal UV absorption allows its use as a printable nanofiller at weight fractions up to 0.35 vol %, preserving the curing depth and optical clarity required for DLP. Postprinting thermal reduction of GO into reduced graphene oxide (rGO) yields nanocomposites with conductivities up to 10<sup>–2</sup> S m<sup>–1</sup>─comparable to conventional carbon nanotube (CNT) systems but achieved without high UV attenuation. To tackle the second question, the authors explored the use of single-walled carbon nanotubes (SWCNTs), which, due to their high aspect ratio and intrinsic conductivity, exhibit ultralow percolation thresholds (<0.01 vol %). At these concentrations, UV interference is negligible. However, the need for surfactant-assisted dispersion introduces contact resistance, limiting conductivity. To overcome this, this Account presents a hybrid formulation in which GO serves as both dispersant and conductive additive, enhancing internanotube contacts upon reduction. This approach achieves conductivities up to 0.3 S m<sup>–1</sup>, with a total filler content below 0.15 vol %, representing a significant leap in performance without sacrificing resolution. To resolve the third question regarding electrical anisotropy, the study employs polarized Raman spectroscopy, conclusively showing that nanotube alignment is not responsible for the observed directional conductivity differences. Instead, the anisotropy arises from interfacial contact resistance between printed layers, an intrinsic artifact of the layer-by-layer DLP process. Mitigation strategies such as delayed UV curing and temperature-controlled printing were shown to significantly reduce this resistance and improve isotropy.</p><p >Beyond addressing these scientific questions, this Account highlights the practical impact of these materials. Notably, hybrid nanocomposites exhibited strong potential in microwave absorption, reaching broadband reflection losses below −10 dB at low filler loadings, due to combined ohmic and dielectric losses. These outcomes demonstrate that high-resolution, fast DLP printing of conductive materials is not only feasible but also tunable and scalable for applications in sensors, soft robotics, and electromagnetic shielding. By answering these key questions, the work establishes a foundation for the rational design of printable conductive nanocomposites, balancing optical compatibility, conductivity, and mechanical precision─paving the way for next-generation functional devices fabricated through vat photopolymerization.</p>\",\"PeriodicalId\":72040,\"journal\":{\"name\":\"Accounts of materials research\",\"volume\":\"6 5\",\"pages\":\"661–671 661–671\"},\"PeriodicalIF\":14.7000,\"publicationDate\":\"2025-05-02\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Accounts of materials research\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://pubs.acs.org/doi/10.1021/accountsmr.5c00060\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Accounts of materials research","FirstCategoryId":"1085","ListUrlMain":"https://pubs.acs.org/doi/10.1021/accountsmr.5c00060","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
摘要
近年来,在多功能3d打印需求不断增长的推动下,将导电纳米材料集成到基于光聚合物的增材制造(AM)中的努力激增。虽然已有几种增材制造技术被用于加工导电复合材料,但数字光处理(DLP)以其高分辨率和快速固化能力脱颖而出。然而,它提出了一个核心限制:印刷树脂的光学透明度要求,这是由传统的导电填料的掺入折衷。本报告强调了在克服该领域的三个基本挑战方面取得的进展:(i)如何在不影响分辨率的情况下通过DLP打印导电纳米复合材料?(ii)如何在低填料含量下实现高导电性?(三)印刷物体的各向异性电导率的来源是什么,如何减轻这种现象?为了解决第一个问题,作者介绍了一种基于紫外线透明前体的策略,特别是单层氧化石墨烯(GO)。氧化石墨烯的最小紫外吸收允许其用作可打印的纳米填料,重量分数高达0.35 vol %,保持DLP所需的固化深度和光学清晰度。印刷后将氧化石墨烯热还原成还原氧化石墨烯(rGO),得到的纳米复合材料的电导率高达10-2 S m-1,与传统的碳纳米管(CNT)系统相当,但没有高紫外线衰减。为了解决第二个问题,作者探索了单壁碳纳米管(SWCNTs)的使用,由于其高宽高比和固有电导率,表现出超低的渗透阈值(<0.01 vol %)。在这种浓度下,紫外线的干扰可以忽略不计。然而,对表面活性剂辅助分散的需要引入了接触电阻,限制了导电性。为了克服这个问题,本报告提出了一种混合配方,其中氧化石墨烯既可以作为分散剂又可以作为导电添加剂,在还原时增强纳米管间的接触。该方法可实现高达0.3 S m-1的电导率,总填料含量低于0.15 vol %,在不牺牲分辨率的情况下实现了性能的显著飞跃。为了解决关于电各向异性的第三个问题,该研究采用了极化拉曼光谱,最终表明纳米管的排列不是观测到的定向电导率差异的原因。相反,各向异性是由印刷层之间的界面接触电阻引起的,这是逐层DLP工艺的固有产物。研究表明,延迟UV固化和温控印刷等缓解策略可以显着降低这种阻力并改善各向同性。除了解决这些科学问题外,本报告还强调了这些材料的实际影响。值得注意的是,杂化纳米复合材料在微波吸收方面表现出强大的潜力,在低填料负载下,由于欧姆和介电损失的综合影响,其宽带反射损失低于- 10 dB。这些结果表明,导电材料的高分辨率,快速DLP打印不仅可行,而且可调和可扩展,适用于传感器,软机器人和电磁屏蔽。通过回答这些关键问题,这项工作为合理设计可印刷的导电纳米复合材料奠定了基础,平衡了光学相容性、导电性和机械精度,为通过还原光聚合制造下一代功能器件铺平了道路。
Vat Photopolymerization 3D Printing of Conductive Nanocomposites
Recent years have witnessed a surge in efforts to integrate electrically conductive nanomaterials into photopolymer-based additive manufacturing (AM), driven by the growing demand for multifunctional 3D-printing. While several AM techniques have been adapted to process conductive composites, Digital Light Processing (DLP) stands out for its high-resolution and fast-curing capabilities. However, it poses a central limitation: the requirement for optical transparency in the printing resin, which is compromised by the incorporation of conventional conductive fillers. This Account highlights the advances in overcoming three fundamental challenges in the field: (i) How can conductive nanocomposites be printed by DLP without compromising resolution? (ii) How can high electrical conductivity be achieved at low filler content? (iii) What is the origin of anisotropic conductivity in printed objects, and how can it be mitigated?
To address the first question, the authors introduced a strategy based on UV-transparent precursors, specifically monolayer graphene oxide (GO). GO’s minimal UV absorption allows its use as a printable nanofiller at weight fractions up to 0.35 vol %, preserving the curing depth and optical clarity required for DLP. Postprinting thermal reduction of GO into reduced graphene oxide (rGO) yields nanocomposites with conductivities up to 10–2 S m–1─comparable to conventional carbon nanotube (CNT) systems but achieved without high UV attenuation. To tackle the second question, the authors explored the use of single-walled carbon nanotubes (SWCNTs), which, due to their high aspect ratio and intrinsic conductivity, exhibit ultralow percolation thresholds (<0.01 vol %). At these concentrations, UV interference is negligible. However, the need for surfactant-assisted dispersion introduces contact resistance, limiting conductivity. To overcome this, this Account presents a hybrid formulation in which GO serves as both dispersant and conductive additive, enhancing internanotube contacts upon reduction. This approach achieves conductivities up to 0.3 S m–1, with a total filler content below 0.15 vol %, representing a significant leap in performance without sacrificing resolution. To resolve the third question regarding electrical anisotropy, the study employs polarized Raman spectroscopy, conclusively showing that nanotube alignment is not responsible for the observed directional conductivity differences. Instead, the anisotropy arises from interfacial contact resistance between printed layers, an intrinsic artifact of the layer-by-layer DLP process. Mitigation strategies such as delayed UV curing and temperature-controlled printing were shown to significantly reduce this resistance and improve isotropy.
Beyond addressing these scientific questions, this Account highlights the practical impact of these materials. Notably, hybrid nanocomposites exhibited strong potential in microwave absorption, reaching broadband reflection losses below −10 dB at low filler loadings, due to combined ohmic and dielectric losses. These outcomes demonstrate that high-resolution, fast DLP printing of conductive materials is not only feasible but also tunable and scalable for applications in sensors, soft robotics, and electromagnetic shielding. By answering these key questions, the work establishes a foundation for the rational design of printable conductive nanocomposites, balancing optical compatibility, conductivity, and mechanical precision─paving the way for next-generation functional devices fabricated through vat photopolymerization.