Transient Behavior of Self-Healable Ultra-Stretchable Carboxylic Acid-Doped Polyaniline Films for Sustainable and Re-processable Polymer Electronics

Abstract

This work evaluates the degradation capabilities of transient carboxylic acid-based dopants (CABDs), focusing on 1,2,4-benzene tricarboxylic acid (BA), citric acid (CA), and diphenic acid (DA). The stretchable electronic polymer complex is composed of polyaniline (PANI), poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAAMPSA), and CABDs. The sensor is synthesized through the oxidative polymerization of aniline while PAAMPSA acts as a template to guide the PANI polymerization. Structural variations among the dopants—including acidity, aromaticity, and rigidity—significantly influenced conductivity, mechanical properties, water retention, and self-healing efficiency. The PANI/PAAMPSA/BA composite exhibited the highest conductivity (0.0063 S/m), while PANI/PAAMPSA/CA demonstrated exceptional stretchability (elongation at break of 3823%), the greatest water retention (15.1%), and a complete conductivity self-healing efficiency (100%). The degradation tests were carried out under soil burial and aqueous conditions. Interestingly, the films completely dissolved in distilled water, tap water and river water within 10 minutes. In addition, the dissolved solution could be recast to develop new functional sensors, indicating the reusability of the sensors. Soil degradation tests further demonstrated the degradation of the film within 24 hours. These findings confirm the potential of carboxylic acid-doped polymeric sensors as sustainable, eco-friendly materials for sensing applications that combine efficient degradability with re-processibility to minimize environmental impact.