Tough and Self-Healing Hydrogels from Polyampholytes
Polyampholyte (PA) hydrogels have attracted great attention as an innovative material having tough, self-healing, and viscoelastic behavior. PA hydrogels are synthesized using one-step radical polymerization of equal amounts of oppositely charged ionic mo
- PDF / 2,053,227 Bytes
- 23 Pages / 439.37 x 666.142 pts Page_size
- 30 Downloads / 201 Views
Tough and Self-Healing Hydrogels from Polyampholytes Tao Lin Sun and Kunpeng Cui
Contents 1 Introduction 2 Synthesis and Optimized Structure 2.1 Charge Ratio 2.2 Total Ionic Monomer Concentration 2.3 Chemical Cross-Linker Density 3 Mechanical Behavior 3.1 Hysteresis, Self-Recovery, and Self-Healing Behavior 3.2 Time-Dependent of Tensile and Fracture Behavior 4 Toughening Mechanism 5 Applications 5.1 Adhesion 5.2 Fiber-Reinforced Soft Composite 6 Summary References
Abstract Polyampholyte (PA) hydrogels have attracted great attention as an innovative material having tough, self-healing, and viscoelastic behavior. PA hydrogels are synthesized using one-step radical polymerization of equal amounts of oppositely charged ionic monomers at a very high monomer concentration. They have 50–70 wt% of water at an equilibrium state, much lower than that of conventional hydrogels that usually have a high-water content (>80%). They are strongly viscoelastic and have a high toughness (fracture energy of 1,000–4,000 J/m2), a high
T. L. Sun (*) South China Advanced Institute for Soft Matter Science and Technology, South China University of Technology, Guangzhou, China e-mail: [email protected] K. Cui Laboratory of Soft and Wet Matter, Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Japan
T. L. Sun and K. Cui
modulus (0.01–8 MPa), a high failure strain (150–1,500%), and a failure stress (0.1–2 MPa), together with 100% self-recovery and a high self-healing efficiency behavior. These excellent mechanical performances are comparable to that of rubbers, most tough double-network hydrogels, and soft bio-tissues. The extensive experimental studies show that these multiple mechanical properties are related to the formation of dynamical features of inter- and intra-chain ionic bonds, and this study opens a common strategy to develop tough and self-healing hydrogels. Keywords Ionic bond · Polyampholyte hydrogel · Self-healing · Toughness · Viscoelastic
1 Introduction Hydrogels are a class of cross-linked polymer network swollen with a large amount of water. Their high permeabilities to small molecules make hydrogels undergo the reversible volume change by imbibing or exuding water in response to change in temperature, light, pH, ionic strength, etc. [1–7]. The reversible volume changes have been used to develop sensors and actuators. Furthermore, hydrogels bear some similarities to biological tissues as a result of their soft and wet nature and have been investigated for use in medical applications, such as extracellular matrix, drug delivery, and tissue regeneration [8–10]. However, conventional hydrogels are often brittle and weak, and thus little attention was paid to them as structural materials, which substantially limit the scope of their applications [11–13]. For example, recent advances in soft device such as loudspeakers, touch pads, electroluminescent displays, electronic skins, etc., require the hydrogels with highly stretchable, mechanical tough, and fatigue resistance behavior
Data Loading...