Stimuli-responsive conductive hydrogels: design, property and applications

Abstract Highly stretched and conductive hydrogels, especially synthetized from natural polymers, are beneficial for highly stretched electronic equipment which is applied in extreme environment. We designed and prepared robust and tough alginate hydrogels (GMA-SA-PAM) using the ingenious strategy of fully interpenetrating cross-linking, in which the glycidyl methacrylate (GMA) was used to modify sodium alginate (SA) and then copolymerized with acrylamide (AM) and methylenebisacrylamide (BIS) as cross-linkers. The complete cross-linked structures can averagely dissipate energy and the polymer structures can maintain hydrogels that are three-dimensional to greatly improve the mechanical performance of hydrogels. The GMA-SA-PAM hydrogels display ultra-stretchable (strain up to ∼407% of tensile strain) and highly compressible (∼57% of compression strain) properties. In addition, soaking the GMA-SA-PAM hydrogel in 5 wt% NaCl solution also endows the conductivity of the hydrogel (this hydrogel was named as GSP-Na) with excellent conductive properties (5.26 S m−1). The GSP-Na hydrogel with high stability, durability, as well as wide range extent sensor is also demonstrated by researching the electrochemical signals and showing the potential for applications in wearable and quickly responded electronics.

Download Full-text

Robust Conductive Hydrogels with Ultrafast Self-Recovery and Nearly Zero Response Hysteresis for Epidermal Sensors

Nanomaterials ◽

10.3390/nano11071854 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1854

Author(s):

Xiuru Xu ◽

Chubin He ◽

Feng Luo ◽

Hao Wang ◽

Zhengchun Peng

Keyword(s):

Guar Gum ◽

Strain Range ◽

Sio2 Nanoparticles ◽

Fast Response ◽

Gauge Factor ◽

Practical Applications ◽

Hydroxypropyl Guar ◽

Stable Chemical ◽

Conductive Hydrogel ◽

Conductive Hydrogels

Robust conductive hydrogels are in great demand for the practical applications of smart soft robots, epidermal electronics, and human–machine interactions. We successfully prepared nanoparticles enhanced polyacrylamide/hydroxypropyl guar gum/acryloyl-grafted chitosan quaternary ammonium salt/calcium ions/SiO2 nanoparticles (PHC/Ca2+/SiO2 NPs) conductive hydrogels. Owing to the stable chemical and physical hybrid crosslinking networks and reversible non-covalent interactions, the PHC/Ca2+/SiO2 NPs conductive hydrogel showed good conductivity (~3.39 S/m), excellent toughness (6.71 MJ/m3), high stretchability (2256%), fast self-recovery (80% within 10 s, and 100% within 30 s), and good fatigue resistance. The maximum gauge factor as high as 66.99 was obtained, with a wide detectable strain range (from 0.25% to 500% strain), the fast response (25.00 ms) and recovery time (86.12 ms), excellent negligible response hysteresis, and good response stability. The applications of monitoring the human’s body movements were demonstrated, such as wrist bending and pulse tracking.

Download Full-text

Preparation of Carbon Fiber-Polyacrylamide Composite Hydrogel Based on Surface Electric-Initiated Polymerization

Journal of Nanoelectronics and Optoelectronics ◽

10.1166/jno.2021.3028 ◽

2021 ◽

Vol 16 (6) ◽

pp. 861-868

Author(s):

Mengge Lv ◽

Xinfang Wei ◽

Liwen Peng

Keyword(s):

Composite Material ◽

Carbon Fiber ◽

Electrochemical Polymerization ◽

Crosslinking Agent ◽

Monomer Concentration ◽

Conductive Filler ◽

Composite Effect ◽

Conductive Hydrogel ◽

Graft Modification ◽

Conductive Hydrogels

Conductive hydrogels have shown excellent application prospects in the fields of bioelectronics, tissue engineering, wearable devices, etc. However, its poor compatibility at the organic-inorganic interface affects its mechanical strength and limits its wide application. We prepared carbon fiber-polyacrylamide organic-inorganic composite material by electrochemical polymerization using N,N-methylenebisacrylamide as the crosslinking agent, acrylamide as the monomer, and carbon fiber as the conductive filler. It forms a conductive hydrogel after absorbing water. The effects of monomer concentration, reaction time, and current on the composite material were investigated in this article. The experimental results show that a large number of irregular bumps are produced on the surface of carbon fiber, and various characterization tests show that it is polyacrylamide (PAM) that successfully attached to carbon fiber. Under the same electrochemical polymerization time, the current density and monomer concentration have little effect on the molecular weight which mainly concentrated around 6.2 × 105. The graft modification of PAM reduces the defects on the surface of the carbon fiber, and the composite effect is good.

Download Full-text

High Toughness Multifunctional Organic Hydrogels for Flexible Strain and Temperature Sensor

Journal of Materials Chemistry A ◽

10.1039/d1ta07127k ◽

2021 ◽

Author(s):

Hongjie Chen ◽

Jianren Huang ◽

Jiaontao Liu ◽

Jianfeng Gu ◽

Jundong Zhu ◽

...

Keyword(s):

Temperature Sensor ◽

High Toughness ◽

Conductive Hydrogel ◽

Conductive Hydrogels

Conductive hydrogel has shown extensive application in multifunctional sensors. However, the intrinsic characteristics of conductive hydrogels, such as lacking anti-freezing, mechanical strengthen, and being easily dehydrated have hindered their application...

Download Full-text

Irreversible and Self-Healing Electrically Conductive Hydrogels Made of Bio-Based Polymers

International Journal of Molecular Sciences ◽

10.3390/ijms23020842 ◽

2022 ◽

Vol 23 (2) ◽

pp. 842

Author(s):

Ahmed Ali Nada ◽

Anita Eckstein Andicsová ◽

Jaroslav Mosnáček

Keyword(s):

Renewable Resources ◽

Mechanical Stability ◽

Conductive Polymers ◽

Special Focus ◽

Self Healing ◽

Natural Polymers ◽

Electrically Conductive ◽

Preparation Methods ◽

Cross Links ◽

Conductive Hydrogels

Electrically conductive materials that are fabricated based on natural polymers have seen significant interest in numerous applications, especially when advanced properties such as self-healing are introduced. In this article review, the hydrogels that are based on natural polymers containing electrically conductive medium were covered, while both irreversible and reversible cross-links are presented. Among the conductive media, a special focus was put on conductive polymers, such as polyaniline, polypyrrole, polyacetylene, and polythiophenes, which can be potentially synthesized from renewable resources. Preparation methods of the conductive irreversible hydrogels that are based on these conductive polymers were reported observing their electrical conductivity values by Siemens per centimeter (S/cm). Additionally, the self-healing systems that were already applied or applicable in electrically conductive hydrogels that are based on natural polymers were presented and classified based on non-covalent or covalent cross-links. The real-time healing, mechanical stability, and electrically conductive values were highlighted.

Download Full-text

Bioinspired tough, conductive hydrogels with thermally reversible adhesiveness based on nanoclay confined NIPAM polymerization and a dopamine modified polypeptide

Materials Chemistry Frontiers ◽

10.1039/c9qm00582j ◽

2020 ◽

Vol 4 (1) ◽

pp. 189-196 ◽

Cited By ~ 3

Author(s):

Xiang Di ◽

Chen Hang ◽

Yue Xu ◽

Qiyue Ma ◽

Feifan Li ◽

...

Keyword(s):

Conductive Hydrogel ◽

Conductive Hydrogels

A multifunctional conductive hydrogel with controllable adhesiveness, high strechability and excellent biocompatibility based on PDAEA, clay, and PNIPAM.

Download Full-text

Incorporation of Conductive Materials into Hydrogels for Tissue Engineering Applications

Polymers ◽

10.3390/polym10101078 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1078 ◽

Cited By ~ 30

Author(s):

Ji Min ◽

Madhumita Patel ◽

Won-Gun Koh

Keyword(s):

Tissue Engineering ◽

Electrical Properties ◽

Cardiac Tissue ◽

In Situ Polymerization ◽

Nerve Tissue ◽

Conductive Materials ◽

Conductive Hydrogel ◽

Conductive Hydrogels ◽

Electrical Properties Of Tissues

In the field of tissue engineering, conductive hydrogels have been the most effective biomaterials to mimic the biological and electrical properties of tissues in the human body. The main advantages of conductive hydrogels include not only their physical properties but also their adequate electrical properties, which provide electrical signals to cells efficiently. However, when introducing a conductive material into a non-conductive hydrogel, a conflicting relationship between the electrical and mechanical properties may develop. This review examines the strengths and weaknesses of the generation of conductive hydrogels using various conductive materials such as metal nanoparticles, carbons, and conductive polymers. The fabrication method of blending, coating, and in situ polymerization is also added. Furthermore, the applications of conductive hydrogel in cardiac tissue engineering, nerve tissue engineering, and bone tissue engineering and skin regeneration are discussed in detail.

Download Full-text

Highly stretchable, self-adhesive, biocompatible, conductive hydrogels as fully polymeric strain sensors

Journal of Materials Chemistry A ◽

10.1039/d0ta07390c ◽

2020 ◽

Vol 8 (39) ◽

pp. 20474-20485

Author(s):

Dong Zhang ◽

Yijing Tang ◽

Yanxian Zhang ◽

Fengyu Yang ◽

Yonglan Liu ◽

...

Keyword(s):

Strain Sensors ◽

Surface Adhesion ◽

Human Movements ◽

Conductive Hydrogel ◽

Highly Stretchable ◽

Strong Surface ◽

Conductive Hydrogels

A new fully polymeric conductive hydrogel sensor with IPN structure was developed, which achieved ultra-high stretchability, strong surface adhesion, and high sensing stability in response to both large and subtle human movements.

Download Full-text