聚(3,4-亞乙二氧基噻吩)-聚(苯乙烯磺酸) (PEDOT:PSS)是一種已被廣泛研究的導電性高分子，並且其水性分散液具備低毒性與剪切稀化的流變特性，因此PEDOT：PSS常適用於儲能、生物電子學和穿戴式傳感器。然而，PEDOT:PSS材料之拉伸率低，且水溶性高，所以在應用方面仍有相當多的限制。本研究嘗試以高分子膠體，丁腈橡膠乳液（Nitrile butadiene rubber latex, NBR latex）來克服PEDOT：PSS之缺點，以開闢一條3D列印導電性複合物之新穎途徑。我們透過調整PEDOT:PSS與NBR乳液之含量來製造可使用於可直接書寫式列印（Direct ink writing）之墨水。列印後之材料再以大量乙醇進行溶劑交換與乾燥，進而形成具備緻密結構之PEDOT:PSS/NBR複合物。此PEDOT:PSS/NBR複合物具備諸多優點，如抗水性、導電具與拉伸能力，並可用於電容式感測器。簡言之，本研究為人體監測傳感器之應用，提供了一個可3D列印的導電性高分子複合材料。

Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is a well-known conducting polymer that exhibits shear thinning behavior, low toxicity, and processability in water. Therefore, PEDOT:PSS is a promising material for energy storage, bioelectronics, and wearable sensors. However, the application of PEDOT:PSS is limited by its poor stretchability and high solubility in water. In this work, we utilized polymeric colloids such as nitrile butadiene rubber (NBR) latex to overcome the disadvantage of PEDOT:PSS and to open a new possibility for the 3D printing of conductive composites. The ink was first prepared by combining NBR latex and PEDOT:PSS, then printed by a direct ink writing process. The printed objects were further immersed in ethanol to remove water and dried to form dense PEDOT:PSS/NBR composites. The PEDOT:PSS/NBR composites exhibited many merits, such as water resistance, electronic conductivity, and stretchability for capacitive sensors. In short, our approach provides a simple route to make 3D printable inks for conductive and tough polymer composites for the application of human body monitoring sensors.

(1) Yuk, H.; Lu, B. -Y.; Lin, S.; Qu, K.; Xu, J. -K.; Luo, J. -H.; Zhao, X. -H. 3D Printing of Conducting Polymers. Nature Communications 2020, 11 (1), 1604.
(2) Rivnay, J.; Inal, S.; Collins, B. -A.; Sessolo, M.; Stavrinidou, E.; Strakosas, X.; Tassone, C.; Delongchamp, D. -M.; Malliaras, G. -G. Structural Control of Mixed Ionic and Electronic Transport in Conducting Polymers. Nature Communications 2016, 7, 11287.
(3) Cheng, T.; Zhang, Y. -Z.; Yi, J. -P.; Yang, L.; Zhang, J. -D.; Lai, W. -Y.; Huang, W. Inkjet-Printed Flexible, Transparent and Aesthetic Energy Storage Devices Based on PEDOT: PSS/Ag Grid Electrodes. Journal of Materials Chemistry A 2016, 4 (36), 13754-13763.
(4) Zajdel, T. -J.; Baruch, M.; Mehes, G.; Stavrinidou, E.; Berggren, M.; Maharbiz, M. -M.; Simon, D. -T.; Ajo-Franklin, C. -M. PEDOT:PSS-based Multilayer Bacterial-Composite Films for Bioelectronics. Scientific Reports 2018, 8, 15293.
(5) Zhao, X.; Wang, W. -L.; Wang, Z.; Wang, J. -N.; Huang, T.; Dong, J.; Zhang, Q. -H. Flexible PEDOT:PSS/Polyimide Aerogels with Linearly Responsive and Stable Properties for Piezoresistive Sensor Applications. Chemical Engineering Journal 2020, 395, 125115.
(6) Hebbar, V.; Bhajantri, R. -F.; Ravikumar, H. -B.; Ningaraju, S. Role of Free Volumes in Conducting Properties of GO and rGO Filled PVA-PEDOT:PSS Composite Free Standing Films: A Positron Annihilation Lifetime Study. Journal of Physics and Chemistry of Solids 2019, 126, 242-256.
(7) Meng, Q. -F.; Cai, K. -F.; Du, Y.; Chen, L. -D. Preparation and Thermoelectric Properties of SWCNT/PEDOT:PSS Coated Tellurium Nanorod Composite Films. Journal of Alloys and Compounds 2019, 778, 163-169.
(8) Ouyang, J. "Secondary doping" Methods to Significantly Enhance the Conductivity of PEDOT:PSS for Its Application as Transparent Electrode of Optoelectronic Devices. Displays 2013, 34 (5), 423-436.
(9) Shi, H.; Liu, C. -C.; Jiang, Q. -L.; Xu, J. -K. Effective Approaches to Improve the Electrical Conductivity of PEDOT:PSS: A Review. Advanced Electronic Materials 2015, 1 (4), 1500017.
(10) Palumbiny, C. -M.; Liu, F.; Russell, T. -P.; Hexemer, A.; Wang, C.; Muller-Buschbaum, P. The Crystallization of PEDOT:PSS Polymeric Electrodes Probed In Situ during Printing. Advanced Materials 2015, 27 (22), 3391-3397.
(11) Xia, Y. -J.; Sun, K.; Ouyang, J. -Y. Highly Conductive Poly(3,4-ethylenedioxythiophene):Poly(styrene sulfonate) Films Treated with an Amphiphilic Fluoro Compound as the Transparent Electrode of Polymer Solar Cells. Energy & Environmental Science 2012, 5 (1), 5325-5332.
(12) Xia, Y. -J.; Sun, K.; Ouyang, J. -Y. Solution-Processed Metallic Conducting Polymer Films as Transparent Electrode of Optoelectronic Devices. Advanced Materials 2012, 24 (18), 2436-2440.
(13) Kim, N.; Kang, H.; Lee, J. -H.; Kee, S.; Lee, S. -H.; Lee, K. Highly Conductive All-Plastic Electrodes Fabricated Using a Novel Chemically Controlled Transfer-Printing Method. Advanced Materials 2015, 27 (14), 2317-2323.
(14) Erich, K.; Eduard, T. Rubber like Masses from Butadiene Hydrocarbons and Polymerizable Nitriles. Google Patents: 1934.
(15) Wang, H.; Yang, L. -J.; Rempel, G. -L. Homogeneous Hydrogenation Art of Nitrile Butadiene Rubber: A Review. Polymer Reviews 2013, 53 (2), 192-239.
(16) Roy, K.; Debnath, S. -C.; Pongwisuthiruchte, A.; Potiyaraj, P. Review on the Conceptual Design of Self-Healable Nitrile Rubber Composites. ACS Omega 2021, 6 (15), 9975-9981.
(17) Zhang, Z. -F.; Liu, X. -T.; Yang, K.; Zhao, S. -G. Design of Coordination-Crosslinked Nitrile Rubber with Self-Healing and Reprocessing Ability. Macromolecular Research 2019, 27 (8), 803-810.
(18) Das, M.; Pal, S.; Naskar, K. Exploring Various Metal-Ligand Coordination Bond Formation in Elastomers: Mechanical Performance and Self-Healing Behavior. Express Polymer Letters 2020, 14 (9), 860-880.
(19) Liu, X. -H.; Lu, C. -H.; Wu, X. -D.; Zhang, X. -X. Self-Healing Strain Sensors Based on Nanostructured Supramolecular Conductive Elastomers. Journal of Materials Chemistry A 2017, 5 (20), 9824-9832.
(20) Yang, G. -Y.; Qin, L. -M.; Li, M. -R.; Ou, K. -T.; Fang, J.; Fu, Q.; Sun, Y. -Y. Shear-Induced Alignment in 3D-Printed Nitrile Rubber-Reinforced Glass Fiber Composites. Composites Part B-Engineering 2022, 229, 109479.
(21) Ambrosi, A.; Pumera, M. 3D-Printing Technologies for Electrochemical Applications. Chemical Society Reviews 2016, 45 (10), 2740-2755.
(22) Kim, G. -B.; Lee, S.; Kim, H.; Yang, D. -H.; Kim, Y. -H.; Kyung, Y. -S.; Kim, C. -S.; Choi, S. -H.; Kim, B. -J.; Ha, H.; et al. Three-Dimensional Printing: Basic Principles and Applications in Medicine and Radiology. Korean Journal of Radiology 2016, 17 (2), 182-197.
(23) Tsai, H. -Y; Yu, S. -S. Ultra-Tough and 3D Printable Poly(vinyl alcohol)/Cellulose Canocrystals Reinforced Conductive Nanocomposite Deep Eutectic Solvent Gels for Textile. National Cheng Kung University (Master thesis) 2022.
(24) Lo, T. -H.; Yu, S. -S. 3D Printable and Sub-Micrometer Porous Polymeric Monoliths with Shape Reconfiguration Ability by Miniemulsion Templating. Macromolecular Materials and Engineering 2022, 307 (1), 2100615.
(25) Lahtinen, M.; Glad, E.; Koskimies, S.; Sundholm, F.; Rissanen, K. Synthesis of Novel Reactive Coalescing Agents and Their Application in a Latex Coating. Journal of Applied Polymer Science 2003, 87 (4), 610-615.
(26) Yang, Y.; Li, M.; Fu, S. -H. Monodispersed Colored Polymer Latex Particles with Film Formation and Chemical Crosslinking for Application on Textile Binder-Free Printing. Colloids and Surfaces a-Physicochemical and Engineering Aspects 2021, 619, 126527.
(27) Yip, E.; Cacioli, P. The Manufacture of Gloves from Natural Rubber Latex. Journal of Allergy and Clinical Immunology 2002, 110 (2), S3-S14.
(28) Arumathanthri, R. -B.; Abeygoonawardana, B. -S. -K.; Kumarasinghe, I. -D. -C. -D.; Chathuranga, D. -S.; Lalitharatne, T. -D.; Kulasekera, A. -L. A Soft Robotic Gripper with Sensory Feedback Fabricated by Latex using Coagulant Dipping Process. In 2018 IEEE International Conference on Robotics and Biomimetics (ROBIO), 12-15 Dec. 2018, 2018, 2082-2087.
(29) Ramli, R.; Mok, K.; Rubaizah, M.; Kamaruddin, S.; Tan, K.-S. Deproteinized Natural Rubber Latex Slow-recovery Foam Intended for Shoe Insoles Application. Journal of physics and Chemistry of Materials 2020, 7(3), 1-9.
(30) Scott, P. -J.; Meenakshisundaram, V.; Hegde, M.; Kasprzak, C. -R.; Winkler, C. -R.; Feller, K. -D.; Williams, C. -B.; Long, T. -E. 3D Printing Latex: A Route to Complex Geometries of High Molecular Weight Polymers. ACS Applied Materials & Interfaces 2020, 12 (9), 10918-10928.
(31) Srimongkol, S.; Wiroonpochit, P.; Utra, K.; Sethayospongsa, R.; Muthitamongkol, P.; Methachan, B.; Butsri, N.; Srisawadi, S. Carbon-Based Conductive Rubber Composite for 3D Printed Flexible Strain Sensors. Polymers for Advanced Technologies 2022, 34(1), 287-298.
(32) Kim, M.; Choi, J. -W. Rubber Ink Formulations with High Solid Content for Direct-Ink Write Process. Additive Manufacturing 2021, 44, 102023.
(33) Fraden, J. Handbook of Modern Sensors: Physics, Designs, and Applications. Fourth Edition; 2010.
(34) Qin, J.; Yin, L. -J.; Hao, Y. -N.; Zhong, S. -L.; Zhang, D. -L.; Bi, K.; Zhang, Y. -X.; Zhao, Y.; Dang, Z. -M. Flexible and Stretchable Capacitive Sensors with Different Microstructures. Advanced Materials 2021, 33 (34), 2008267.
(35) Obitayo, W.; Liu, T. A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors. Journal of Sensors 2012, 2012, 652438.
(36) Sukhija, M.; Nagsarkar, T. Circuits and Networks: Analysis, Design, and Synthesis. Oxford University Press 2010.
(36) Sukhija, M.; Nagsarkar, T. Circuits and Networks: Analysis, Design, and
Synthesis. Oxford University Press 2010.
(37) Baxter, L. -K. Capacitive Sensors. Design and Applications 1997.
(38) Rivadeneyra, A.; Lopez-Villanueva, J. -A. Recent Advances in Printed
Capacitive Sensors. Micromachines 2020, 11 (4).
(39) Puers, R. Capacitive Sensors: When and How to Use Them. Sensors and
Actuators A: Physical 1993, 37, 93-105.
(40) Huang, S.; Plaskowski, A.; Xie, C.; Beck, M. Tomographic Imaging of TwoComponent Flow Using Capacitance Sensors. Journal of Physics E: Scientific
Instruments 1989, 22 (3), 173.
(41) Xie, C.; Stott, A.; Plaskowski, A.; Beck, M. Design of Capacitance Electrodes
for Concentration Measurement of Two-Phase Flow. Measurement Science and
Technology 1990, 1 (1), 65.
81
(42) Wang, M. -X.; Gao, Q.; Gao, J. -F.; Zhu, C. -H.; Chen, K. -L. Core-Shell
PEDOT:PSS/SA Composite Fibers Fabricated via a Single-Nozzle Technique
Enable Wearable Sensor Applications. Journal of Materials Chemistry C 2020, 8
(13), 4564-4571.
(43) Wang, Z. -Y.; Wang, T.; Zhuang, M. -D.; Xu, H. -X. Stretchable Polymer
Composite with a 3D Segregated Structure of PEDOT:PSS for Multifunctional
Touchless Sensing. ACS Applied Materials & Interfaces 2019, 11 (48), 45301-45309.