Mechanically robust, notch-insensitive, fatigue resistant and self-recoverable hydrogels with homogeneous and viscoelastic network constructed by a novel multifunctional cross-linker. (28th September 2019)

• Record Type: Journal Article
• Authors: Wang, Yi; Wu, Jinrong; Cao, Zhenxing; Ma, Changshu; Tong, Qingbo; Li, Jiangbo; Liu, Hanchao; Zheng, Jing; Huang, Guangsu
• Is Part Of: Polymer. Volume 179(2019)
• Publication Date: 2019-09-28
• Subjects: Multifunctional cross-linker -- Mechanical properties -- Inhomogeneity and viscoelasticity; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2019.121661
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Designing a homogeneous network is an efficient way to improve the mechanical properties of hydrogels. However, the homogeneous hydrogels usually have negligible notch-insensitivity due to the lack of effective energy dissipation, limiting their practical applications in many fields. Herein, we provide a straightforward method to prepare a category of tough and notch-insensitive polyacrylamide hydrogels crosslinked by a novel cross-linker with multiple vinyl functional groups (TA). Due to the multifunctionality of TA, a relatively uniform network with the coexistence of physical cross-links is constructed by the steric effect between chain radicals on TA molecules during the polymerization. The uniform network distributes stress evenly while the physical cross-links lead to viscoelastic dissipated energy under external force. As a result, the hydrogels achieve an ultrastretchability of 2400% and a tensile toughness of 4.33 MJ/m 3 . Even with a notch of 10 mm, the hydrogels can still be stretched to a strain of 20, indicating an impressive notch-insensitivity. Meanwhile, the hydrogels exhibit high fatigue resistance and good self-recovery. This research offers a facile strategy for designing high-performance hydrogels and may pave the way for their practical application in emerging fields, such as oil displacement agent and artificial cartilage. Graphical abstract: High-performance hydrogels are fabricated by free radical polymerization of acrylamide monomers in the presence of vinyl-functionalized tetraethylenepentamine (TA). TA with vinyl functional groups serves as multifunctional cross-linking centers for polymerization, yielding a homogeneous and viscoelastic network due to the steric effect between chain radicals. The uniform and viscoelastic network allow the TA-crosslinked hydrogels to evenly distribute stress and effectively dissipate energy, thus the hydrogels are tough, notch-insensitive, fatigue resistant and self-recoverable.Image 1 Highlights: ∙ A novel crosslinker with multifunctionality (TA) are fabricated. ∙ Hydrogels crosslinked by TA show homogeneous and viscoelastic network. ∙ The unique network can evenly distribute stress and effectively dissipate energy. ∙ The hydrogels are mechanically robust, notch-insensitive and anti-fatigue.