RESEARCH ARTICLE www.mame-journal.de Patterned Electroconductive Networks in Ag-Polyamide 6 Composites by Laser Ablation Filipa M. Oliveira, Nadya Dencheva, Zlatan Denchev,* Filipe S. Silva, Óscar Carvalho, and Caroline G. Moura* A simple, fast, and cost-effective method to fabricate conductive paths on insulating Ag-containing polyamide 6 (PA6) composites by laser beam treatment is presented in this study. First, Ag-hybrid microparticles (Ag-MP) with a total metal load of up to 19 wt% are synthesized based on a reactive encapsulation strategy utilizing activated anionic polymerization of -caprolactam in solution, in the presence of Ag nanoparticles. Then, the Ag-MP are compression molded into plates (Ag-PL) on which a scanning laser treatment is applied to create conductive paths in their selected parts. A comparison between structural, morphological, and thermal properties of the Ag-MP and the molded Ag-PL composites is performed. The electric conductive properties of the Ag-loaded hybrid materials are investigated before and after laser ablation, and it is concluded that the laser treatment results in selected paths with widths in the range of 500 μm with conductivity values in the range of 1.12 to 8.90 S m -1 while the untreated Ag-PA6 surface remains isolating with conductivity values of 1.27 × 10 -08 Sm -1 . These results prove that applying laser ablation with controlled parameters on initially insulating Ag-PL composites can efficiently produce conductive line patterns in composite plates. 1. Introduction Polymer materials are known for their insulating properties, [1,2] which is a limitation in the development of flexible electrocon- ductive materials. For instance, in a recent work, a bimorph actuator with thermochromic and self-sensing dual functional- ities was prepared through an in situ synthesis on a cellulose paper substrate. [3] To overcome this issue, that is, the implemen- tation of polymer matrices in materials with electrical properties, the combination of metals and polymers has been investigated F. M. Oliveira, N. Dencheva, Z. Denchev Institute for Polymers and Composites University of Minho Campus de Azurém, Guimarães 4800-058, Portugal E-mail: denchev@dep.uminho.pt F. S. Silva, Ó. Carvalho, C. G. Moura Center of Microelectromechanical Systems University of Minho Campus de Azurém, Guimarães 4800-058, Portugal E-mail: caroline.materiais@gmail.com The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/mame.202100308 DOI: 10.1002/mame.202100308 to associate the mechanical and electrical properties of metals with the low density, flexibility, ease of manufacture, and low cost of polymers. [2,4–8] Several studies have demonstrated that the addition of metal par- ticles to polymer matrices improves some properties of the final polymer composite obtained, such as the tensile strength, [9,10] thermal stability, [11–13] and flammability behavior, [11] as well as the optical, [13,14] magnetic, [15–17] electrical, [18,19] and electro- magnetic shielding properties. [18,20] Several methods have been used to combine the advantages of metals and polymers in the same material aiming at its application in electric and electronic areas. Methods like physical vapor deposition, [21] chem- ical vapor deposition, [22] thermal spray metallization, [23] and electroless plating [24] have been used in the development of metal-coated polymer materials. Printing technologies [25,26] are the alternative to fab- ricate devices based on metal-conductive inks, in which polymer matrices reduce the agglomeration and oxidation of the metal particulate fillers that provide electrical conductivity. It is worth noting that these coating and printing techniques require ex- pensive and specific equipment, high processing costs, and the part sizes and shapes may be subject to limitations. The surface modification of a nonconductor fabric substrate by constructing a polymer-metal-polymer sandwich microstructure coating layer on the surface of a polymer fabric is a low-cost alternative to traditional printing technologies. [27] However, if the substrate is not properly prepared, the adhesion of the metal particles to the substrate can be weak, affecting the metal-substrate interface and therefore their electric conductive properties. Alternatively, metal particles can be dispersed in a polymer matrix by reactive processing techniques, in which thermoplas- tic composites are obtained through in situ polymerizations in the presence of the desired payloads. Among the polymeriza- tion processes, ring-opening polymerization (ROP) based on an anionic mechanism is the most common approach. [28,29] Thus, considering the processability, chemical, and mechani- cal resistance of polyamide 6 (PA6), [30] activated anionic ROP (AAROP) of -caprolactam (ECL) can be applied in the pro- duction of PA6 materials. Through reactive microencapsula- tion of metal loads by AAROP of ECL in a suspension, metal- loaded PA6-based microparticles (MP) were obtained, [31,32] and Macromol. Mater. Eng. 2021, 306, 2100308 © 2021 Wiley-VCH GmbH 2100308 (1 of 12)