Novel Conductive AgNP-Based Adhesive Based on Novel Poly (Ionic Liquid)-Based Waterborne Polyurethane Chloride Salts for E-Textiles

• Published in: Polymers 2024-02, Vol.16 (4), p.540
• Main Authors: Liao, Haiyang, Xiao, Yeqi, Xiao, Tiemin, Kuang, Hongjin, Feng, Xiaolong, Sun, Xiao, Cui, Guixin, Duan, Xiaofei, Shi, Pu
• Format: Article
• Language: English
• Subjects: Adhesion; Adhesives; Chloride; Chloride ions; Chlorides; Coatings; Dichloropropane; Electrical resistivity; Electronic materials; Ethanol; External pressure; Fingers; Glycerol; High temperature; Identification and classification; Ionic liquids; Low temperature; Mechanical properties; Molecular chains; Molecular structure; Nanoparticles; NMR; Nuclear magnetic resonance; Polyesters; Polyurethane resins; Polyurethanes; Pressure sensors; Salt; Screen printing; Silver; Sintering; Smart materials; Spectrum analysis; Substrates; Temperature; Textiles; Washing; Wrist
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym16040540

The emergence of novel e-textile materials that combine the inherent qualities of the textile substrate (lightweight, soft, breathable, durable, etc.) with the functionality of micro/nano-electronic materials (conductive, dielectric, sensing, etc.) has resulted in a trend toward miniaturization, integration, and intelligence in new electronic devices. However, the formation of a conductive network by micro/nano-conductive materials on textiles necessitates high-temperature sintering, which inevitably causes substrate aging and component damage. Herein, a bis-hydroxy-imidazolium chloride salt as a hard segment to synthesize a waterborne polyurethane (WPU) adhesive is designed and prepared. When used in nano-silver-based printing coatings, it offers strong adherence for coatings, reaching 16 N cm ; on the other hand, the introduction of chloride ions enables low-temperature (60 °C) chemical sintering to address the challenge of secondary treatment and high-temperature sintering (>150 °C). Printed into flexible circuits, the resistivity can be controlled by the content of imidazolium salts anchored in the molecular chain of the WPU from a maximum resistivity of 3.1 × 10 down to 5.8 × 10 Ω m, and it can conduct a Bluetooth-type finger pulse detector with such low resistivity. As a flexible circuit, it also offers high stability against washing and adhesion, which the resistivity only reduces less than 20% after washing 10 times and adhesion. Owing to the adjustability of the resistivity, we fabricated an all-textile flexible pressure sensor that accurately differentiates different external pressures (min. 10 g, ~29 Pa), recognizes forms, and detects joint motions (finger bending and wrist flexion).