Carbon Nanomaterials Embedded in Conductive Polymers: A State of the Art

Carbon nanomaterials are at the forefront of the newest technologies of the third millennium, and together with conductive polymers, represent a vast area of indispensable knowledge for developing the devices of tomorrow. This review focusses on the most recent advances in the field of conductive nanotechnology, which combines the properties of carbon nanomaterials with conjugated polymers. Hybrid materials resulting from the embedding of carbon nanotubes, carbon dots and graphene derivatives are taken into consideration and fully explored, with discussion of the most recent literature. An introduction into the three most widely used conductive polymers and a final section about the most recent biological results obtained using carbon nanotube hybrids will complete this overview of these innovative and beyond belief materials.The European Union is acknowledged for funding this research through Horizon 2020 MSCA-IF-2018 No 838171 (TEXTHIOL). IMDEA Nanociencia acknowledges support from the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, Grant SEV- 2016-0686). European Regional Development fund Project “MSCAfellow4 @ MUNI” supported by MEYS CR (No. CZ.02.2.69/0.0/0.0/20_079/0017045) is acknowledged. N.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 753293, acronym NanoBEAT

Recent Advances on 2D Materials towards 3D Printing

In recent years, 2D materials have been implemented in several applications due to their unique and unprecedented properties. Several examples can be named, from the very first, graphene, to transition-metal dichalcogenides (TMDs, e.g., MoS2), two-dimensional inorganic compounds (MXenes), hexagonal boron nitride (h-BN), or black phosphorus (BP). On the other hand, the accessible and low-cost 3D printers and design software converted the 3D printing methods into affordable fabrication tools worldwide. The implementation of this technique for the preparation of new composites based on 2D materials provides an excellent platform for next-generation technologies. This review focuses on the recent advances of 3D printing of the 2D materials family and its applications; the newly created printed materials demonstrated significant advances in sensors, biomedical, and electrical applications.Financial support from Operational Program Research, Development and Education-Project “MSCAfellow4@MUNI” (CZ.02.2.69/0.0/0.0/20_079/0017045) is acknowledged

Thiophene-Based Trimers and Their Bioapplications: An Overview

Certainly, the success of polythiophenes is due in the first place to their outstanding electronic properties and superior processability. Nevertheless, there are additional reasons that contribute to arouse the scientific interest around these materials. Among these, the large variety of chemical modifications that is possible to perform on the thiophene ring is a precious aspect. In particular, a turning point was marked by the diffusion of synthetic strategies for the preparation of terthiophenes: the vast richness of approaches today available for the easy customization of these structures allows the finetuning of their chemical, physical, and optical properties. Therefore, terthiophene derivatives have become an extremely versatile class of compounds both for direct application or for the preparation of electronic functional polymers. Moreover, their biocompatibility and ease of functionalization make them appealing for biology and medical research, as it testifies to the blossoming of studies in these fields in which they are involved. It is thus with the willingness to guide the reader through all the possibilities offered by these structures that this review elucidates the synthetic methods and describes the full chemical variety of terthiophenes and their derivatives. In the final part, an in-depth presentation of their numerous bioapplications intends to provide a complete picture of the state of the art.Operational Program Research, Development, and Education Project “MSCAfellow4@MUNI” (No. CZ.02.2.69/0.0/0.0/20_079/0017045) is acknowledged. The European Union is acknowledged for funding this research through Horizon 2020 MSCA-IF-2018 No 838171 (TEXTHIOL)

2D and 3D Immobilization of Carbon Nanomaterials into PEDOT via Electropolymerization of a Functional Bis-EDOT Monomer

Carbon nanomaterials (CNMs) and conjugated polymers (CPs) are actively investigated in applications such as optics, catalysis, solar cells, and tissue engineering. Generally, CNMs are implemented in devices where the relationship between the active elements and the micro and nanostructure has a crucial role. However, they present some limitations related to solubility, processibility and release or degradability that affect their manufacturing. CPs, such as poly(3,4-ethylenedioxythiophene) (PEDOT) or derivatives can hide this limitation by electrodeposition onto an electrode. In this work we have explored two different CNMs immobilization methods in 2D and 3D structures. First, CNM/CP hybrid 2D films with enhanced electrochemical properties have been developed using bis-malonyl PEDOT and fullerene C60. The resulting 2D films nanoparticulate present novel electrochromic properties. Secondly, 3D porous self-standing scaffolds were prepared, containing carbon nanotubes and PEDOT by using the same bis-EDOT co-monomer, which show porosity and topography dependence on the composition. This article shows the validity of electropolymerization to obtain 2D and 3D materials including different carbon nanomaterials and conductive polymers.This research was funded by the Spanish Ministry of Economy and Competitiveness MINECO (project CTQ2016-76721-R), the University of Trieste, Diputación Foral de Gipuzkoa program Red (101/16), the European Commission (H2020-MSCA-RISE-2016, grant agreement no. 734381, acronym CARBO-IMmap) and ELKARTEK bmG2017 (ref: Elkartek KK-2017/00008, BOPV resolution: 8 Feb 2018). M.P., as the recipient of the AXA Chair, is grateful to the AXA Research Fund for financial support. This work was performed under the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency Grant no. MDM-2017-0720. N.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 753293, acronym NanoBEAT

Additive Manufacturing of Conducting Polymers: Recent Advances, Challenges and Opportunities

Unformatted postprintConducting polymers (CPs) have been attracting great attention in the development of (bio)electronic devices. Most of current devices are rigid 2D systems and possess uncontrollable geometries and architectures that lead to poor mechanical properties presenting ion/electronic diffusion limitations. The goal of the article is to provide an overview about the additive manufacturing (AM) of conducting polymers, which is of paramount importance for the design of future wearable 3D (bio)electronic devices. Among different 3D printing AM techniques, inkjet, extrusion, electrohydrodynamic and light-based printing have been mainly used. This review article collects examples of 3D printing of conducting polymers such as poly(3,4-ethylene-dioxythiophene) (PEDOT), polypyrrole (PPy) and polyaniline (PANi). It also shows examples of AM of these polymers combined with other polymers and/or conducting fillers such as carbon nanotubes, graphene and silver nanowires. Afterwards, the foremost application of CPs processed by 3D printing techniques in the biomedical and energy fields, i.e., wearable electronics, sensors, soft robotics for human motion, or health monitoring devices, among others, will be discussed.This work was supported by Marie Sklodowska-Curie Research and Innovation Staff Exchanges (RISE) under the grant agreement No 823989 “IONBIKE”. N.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 753293, acronym NanoBEAT

Fast Visible-Light Photopolymerization in the Presence of Multiwalled Carbon Nanotubes: Toward 3D Printing Conducting Nanocomposites

[EN] A new photoinitiator system (PIS) based on riboflavin (Rf), triethanolamine, and multiwalled carbon nanobutes (MWCNTs) is presented for visible-light-induced photopolymerization of acrylic monomers. Using this PIS, photopolymerization of acrylamide and other acrylic monomers was quantitative in seconds. The intervention mechanism of CNTs in the PIS was studied deeply, proposing a surface interaction of MWCNTs with Rf which favors the radical generation and the initiation step. As a result, polyacrylamide/MWCNT hydrogel nanocomposites could be obtained with varying amounts of CNTs showing excellent mechanical, thermal, and electrical properties. The presence of the MWCNTs negatively influences the swelling properties of the hydrogel but significantly improves its mechanical properties (Young modulus values) and electric conductivity. The new PIS was tested for 3D printing in a LCD 3D printer. Due to the fast polymerizations, 3D-printed objects based on the conductive polyacrylamide/CNT nanocomposites could be manufactured in minutes.The authors are thankful for technical and human support provided by IZO-SGI SGIker of UPV/EHU. The authors would like to thank the European Commission for financial support through funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 823989

Digital Light 3D Printing of PEDOT-Based Photopolymerizable Inks for Biosensing

3D conductive materials such as polymers and hydrogels that interface between biology and electronics are actively being researched for the fabrication of bioelectronic devices. In this work, short-time (5 s) photopolymerizable conductive inks based on poly(3,4-ethylenedioxythiophene) (PEDOT):polystyrene sulfonate (PSS) dispersed in an aqueous matrix formed by a vinyl resin, poly(ethylene glycol) diacrylate (PEGDA) with different molecular weights (M-n = 250, 575, and 700 Da), ethylene glycol (EG), and a photoinitiator have been optimized. These inks can be processed by Digital Light 3D Printing (DLP) leading to flexible and shape-defined conductive hydrogels and dry conductive PEDOTs, whose printability resolution increases with PEGDA molecular weight. Besides, the printed conductive PEDOT-based hydrogels are able to swell in water, exhibiting soft mechanical properties (Young's modulus of similar to 3 MPa) similar to those of skin tissues and good conductivity values (10(-2) S cm(-1)) for biosensing. Finally, the printed conductive hydrogels were tested as bioelectrodes for human electrocardiography (ECG) and electromyography (EMG) recordings, showing a long-term activity, up to 2 weeks, and enhanced detection signals compared to commercial Ag/AgCl medical electrodes for health monitoring.This work was supported by Marie Sklodowska-Curie Research and Innovation Staff Exchanges (RISE) under grant agreement No. 823989 “IONBIKE”

Electroactive 3D printable poly (3,4-ethylenedioxythiophene)-graft-poly(ε-caprolactone) copolymers as scaffolds for muscle cell alignment

Unformatted postprintThe development of tailor-made polymers to build artificial three-dimensional scaffolds to repair damaged skin tissues is gaining increasing attention in the bioelectronics field. Poly (3,4-ethylene dioxythiophene) (PEDOT) is the gold standard conducting polymer for the bioelectronics field due to its high conductivity, thermal stability, and biocompatibility; however, it is insoluble and infusible, which limits its processability into three dimensional scaffolds. Here, poly(3,4-ethylendioxythiophene)-graft-poly(ε−caprolactone) copolymers, PEDOT-g-PCL, with different molecular weights and PEDOT compositions, were synthesized by chemical oxidative polymerization to enhance the processability of PEDOT. First, the chemical structure and composition of the copolymers were characterized by nuclear magnetic resonance, infrared spectroscopy, and thermogravimetric analysis. Then, the additive manufacturing of PEDOT-g-PCL copolymers by direct ink writing was evaluated by rheology and 3D printing assays. The morphology of the printed patterns was further characterized by scanning electron microscopy and the conductivity by the four-point probe. Finally, the employment of these printed patterns to induce muscle cells alignment was tested, proving the ability of PEDOT-g-PCL patterns to produce myotubes differentiation.This work was funded by the spanish AEI-MICINN project PID2020-119026GB-I00 and Basque Government through grant IT1309-19. J. L. O.-M. thanks the Consejo Nacional de Ciencia y Tecnología (CONACyT, México) for the grant awarded no. 471837

3D Printable Conducting and Biocompatible PEDOT-graft-PLA Copolymers by Direct Ink Writing

Tailor-made polymers are needed to fully exploit the possibilities of additive manufacturing, constructing complex and functional devices in areas such as bioelectronics. In this article, we show the synthesis of a conducting and biocompatible graft copolymer which can be 3D printed using direct melting extrusion methods. For this purpose, graft copolymers composed by conducting polymer poly(3,4-ethylenedioxythiophene) PEDOT and a biocompatible polymer polylactide (PLA) were designed. The PEDOT-g-PLA copolymers were synthesized by chemical oxidative polymerization between 3,4-ethylenedioxythiophene and PLA macromonomers. PEDOT-g-PLA copolymers with different compositions were obtained and fully characterized. The rheological characterization indicated that copolymers containing bellow 20wt% of PEDOT showed the right complex viscosity values suitable for Direct Ink Writing. The 3D printing tests using the direct ink writing (DIW) methodology allowed to print different parts with different shapes with high resolution (200 μm). The conductive and biocompatible printed patterns of PEDOT-g-PLA showed excellent cell growth and maturation of neonatal cardiac myocytes co-cultured with fibroblasts.This work was supported by funding from Health Institute Carlos III (ISCIII) funds and by Marie Sklowdowska-Curie Research and Innovation Staff Exchanges (RISE) under the grant agreement N0 823989

Three-Dimensional Conductive Scaffolds as Neural Prostheses Based on Carbon Nanotubes and Polypyrrole

Unformatted post printThree-dimensional scaffolds for cellular organization need to enjoy a series of specific properties. On the one hand, the morphology, shape and porosity are critical parameters and eventually related with the mechanical properties. On the other hand, electrical conductivity is an important asset when dealing with electroactive cells, so it is a desirable property even if the conductivity values are not particularly high. Here, we construct three-dimensional (3D) porous and conductive composites, where C8-D1A astrocytic cells were incubated to study their biocompatibility. The manufactured scaffolds are composed exclusively of carbon nanotubes (CNTs), a most promising material to interface with neuronal tissue, and polypyrrole (PPy), a conjugated polymer demonstrated to reduce gliosis, improve adaptability, and increase charge-transfer efficiency in brain-machine interfaces. We developed a new and easy strategy, based on the vapor phase polymerization (VPP) technique, where the monomer vapor is polymerized inside a sucrose sacrificial template containing CNT and an oxidizing agent. After removing the sucrose template, a 3D porous scaffold was obtained and its physical, chemical, and electrical properties were evaluated. The obtained scaffold showed very low density, high and homogeneous porosity, electrical conductivity, and Young’s Modulus similar to the in vivo tissue. Its high biocompatibility was demonstrated even after 6 days of incubation, thus paving the way for the development of new conductive 3D scaffolds potentially useful in the field of electroactive tissues.MP received funding from the Spanish Ministry of Economy and Competitiveness MINECO (project CTQ2016-76721-R), Diputación Foral de Gipuzkoa program Red (101/16) and ELKARTEK bmG2017 (Ref: Elkartek KK-2017/00008, BOPV resolution: 8 Feb 2018). NA has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 753293, acronym NanoBEAT. We acknowledge Donato Mancino for the support given during the revision stage. As well, AXA Research Fund and University of Trieste are gratefully acknowledged