Search for: All records

The development of self-healing materials, particularly self-healing polymers and polymer composites, has opened new pathways toward materials capable of autonomously repairing damage, thereby extending service life and structural reliability across diverse applications. This review article comprehensively reviews the synthesis strategies, self-healing mechanisms, functional implementations, and related application fields. Self-healing polymers depend on reversible chemical bonds and supramolecular interactions, whereas self-healing polymer composites combine these principles with reinforcement materials to merge self-healing capability with increased mechanical strength. Nevertheless, ensuring long-term durability, addressing the trade-off between self-healing performance and mechanical strength, and the lack of standardized evaluation metrics remain key challenges. Finally, this review introduces representative applications in various electronic-device fields and outlines the remaining hurdles and future outlook for practical implementation. 

This study aims to investigate the effects of using different small molecule dopants based on phosphoric acid such as nitrilotrimethylphosphonic acid (NTMPA), 1,1′-binaphthyl-2,2′-diyl hydrogenphosphate (BNHP), and pyrophosphoric acid (PPA) in a polyaniline/poly(2-acrylamido-2-methylpropanesulfonic acid) (PANI/PAAMPSA) polymer complex. The impacts of the size, structure, and number of acid groups of these small molecule dopants on the resulting solvent-cast film properties are examined. The polymer film is synthesized through a templated oxidative polymerization of aniline, where the resulting complex is noncovalently bonded via hydrogen bonding and electrostatic interactions. Fourier transform infrared spectroscopy confirmed the presence of a greater degree of hydrogen bonding in the PANI/PAAMPSA/PPA film, resulting in a greater elongation at break (ε = 3750%) and higher water content (16.3%). The stronger hydrogen bonding in PANI/PAAMPSA/PPA created robust cross-linking within the material, which reduced its ability to self-heal. On the other hand, the PANI/PAAMPSA/NTMPA film achieved high self-healing efficiencies of 98% (conductive self-healability) and 77.3% (mechanical self-healability) due to its more dynamic hydrogen bonding and electrostatic interactions. Furthermore, PANI/PAAMPSA/BNHP showed less hydrogen bonding, stretchability, and self-healing capabilities due to the steric hindrance and hydrophobicity caused by its rigid bulky structure compared to the more linear structures of the other dopants investigated. 

The objective of this perspective is to review the high-interest field of wearable polymer-based sensors—from synthesis to use and detection mechanisms—with a focus on their transient nature, potential for reuse, and ultimate fate. 

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 film 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−1), 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. 

(Invited article as part of the 2026 Pioneering Investigator Collection) This comparative study investigates the role of side-group chemistry in mono-sulfonic acid dopants—CSA, DBSA, and TFMSA—within PANI/PAAMPSA complexes. The structural variations among the dopants significantly influenced the polymer-dopant interactions, which in turn altered key material properties. These findings provide molecular-level insights for developing highly stretchable, conductive, and autonomously self-healing materials for flexible and wearable applications. 

Wearable sensors, stretchable electronics, and many soft robotic materials must have a balance of conductivity, stretchability, and robustness. Intrinsically conductive polymers offer a critical step toward improving wearable sensor materials due to their tunable conductivity, soft/compliant nature, and ability to complex with other coactive molecules (i.e., polyacids, small molecules). The addition of synergistic nanofillers has been shown to enhance the conductivity, self-healing, and mechanical properties of the polymers for soft robotics and wearable applications. The development of a robust polymer nanocomposite material that offers ultra-stretchability, an autonomous self-healing ability, and enhanced electronic properties has long eluded researchers. Herein, we show an aqueous polyaniline [PANI]:poly(2-acrylamido-2-methylpropane sulfonic acid) [PAAMPSA]:phytic acid [PA] polymer complex synthesized with 0.5 wt % silver nanowires (AgNW) to form a polymer nanocomposite with high electronic sensitivity, unique mechanical properties (a maximum strain of 4693%) and repeatable/autonomous self-healing efficiencies of greater than 98%. This AgNW polymer complex has an engineering strain higher than any reported hydrogel or other polymer-based sensor materials, in which the interface between the polymer matrix and the AgNW is hypothesized to be integral for the formation of the active electrically conductive network and unprecedented mechanical properties. To illustrate the remarkable sensitivity, the material was employed as a biomedical sensor (pulse, voice recognition, motion), topographical sensor, and high-sensitivity strain gauge. 

Electrically conductive polymers are a groundbreaking class of materials commonly utilized in medical research focused on healthcare devices such as biosensors. They share the mechanical properties of a classical polymer as well as the electronic properties of metals. This allows them to function as flexible, lightweight, and highly efficient components in both wearable and implantable sensor technologies. Although research has shown promising findings, most of the polymer sensors presented are only partially or not at all biologically compatible with the human body. This work demonstrates a new electroconductive polymer matrix composed of bio‐based materials–bovine gelatin, whey protein isolate (WPI), polyaniline (PANI), and phytic acid (PA)– as a soft, compliant material. The results showed a homogeneous and well‐integrated matrix that remains stable up to . The water content in the samples ranged from 29.99% to 63.81%, depending on the method of preparation. The electromechanical properties before and after self‐healing were also investigated, along with antibacterial properties against both Gram‐positive (S. aureus) and Gram‐negative (E. coli) bacteria. This study developed a new formulation of a conductive polymer matrix that is potentially biocompatible, yet still exhibits satisfactory mechanical properties like its predecessors, making it a candidate for bio‐sensing applications.