Browsing by Author "Wei, Junhua (TTU)"
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Item Thermal-recoverable tough hydrogels enhanced by porphyrin decorated graphene oxide(2019) Wang, Jilong; Wei, Junhua (TTU); Su, Siheng; Qiu, Jingjing (TTU); Hu, Zhonglue; Hasan, Molla; Vargas, Evan (TTU); Pantoya, Michelle (TTU); Wang, ShirenArtificial tissue materials usually suffer properties and structure loss over time. As a usual strategy, a new substitution is required to replace the worn one to maintain the functions. Although several approaches have been developed to restore the mechanical properties of hydrogels, they require direct heating or touching, which cannot be processed within the body. In this manuscript, a photothermal method was developed to restore the mechanical properties of the tough hydrogels by using near infrared (NIR) laser irradiation. By adding the porphyrin decorated graphene oxide (PGO) as the nanoreinforcer and photothermal agent into carrageenan/polyacrylamide double network hydrogels (PDN), the compressive strength of the PDN was greatly improved by 104%. Under a short time of NIR laser irradiation, the PGO effectively converts light energy to thermal energy to heat the PDN hydrogels. The damaged carrageenan network was rebuilt, and a 90% compressive strength recovery was achieved. The PGO not only significantly improves the mechanical performance of PDN, but also restores the compressive property of PDN via a photothermal method. These tough hydrogels with superior photothermal recovery may work as promising substitutes for load-bearing tissues.Item Tough and Fatigue-Resistant Hydrogels with Triple Interpenetrating Networks(2019) Wang, Jilong; Wei, Junhua (TTU); Su, Siheng; Qiu, Jingjing (TTU)Biomimetic hydrogels with triple networks have been developed via in situ polymerization and addition of graphene oxide (GO) nanosheets, which achieve improved toughness and superior fatigue resistance, simultaneously. Compared with pristine calcium alginate/polyacrylamide double network (DN) hydrogels, the integration of a calcium-induced graphene oxide network enhances the crosslinking degree of triple network (TN) hydrogels with improved compressive strength by 172% and toughness by 174%. In addition, cyclic compressive loading-unloading curves depict excellent fatigue resistance because of reversible calcium alginate and calcium-induced GO networks, whereas high strength and toughness of traditional DN gels derive from the first sacrificial network, which leads to inferior fatigue resistance. Toughness of these TN gels was still kept at 110 kJ m-3 at the fifth cycle which is equal to that of articular cartilages. The swelling property of these DN and TN hdyrogels is also systematically explored, which exhibits that GO can reduce the swelling to maintain the mechanical properties of TN gels. The internal fracture mechanisms of these TN hydrogels are studied via swelling tests of precompressed and as-prepared gels. These synergistic effects of the reversible ions crosslinking polymer network and nanofillers open a new platform to design supertough and fatigue-resistant hydrogels. In addition, these TN hydrogels are talented replacements for load-bearing parts, like cartilage due to its high toughness and superior fatigue resistance.Item Ultrasensitive wearable strain sensors of 3D printing tough and conductive hydrogels(2019) Wang, Jilong; Liu, Yan; Su, Siheng; Wei, Junhua (TTU); Rahman, Syed Ehsanur (TTU); Ning, Fuda; Christopher, Gordon (TTU); Cong, Weilong (TTU); Qiu, Jingjing (TTU)In this study, tough and conductive hydrogels were printed by 3D printing method. The combination of thermo-responsive agar and ionic-responsive alginate can highly improve the shape fidelity. With addition of agar, ink viscosity was enhanced, further improving its rheological characteristics for a precise printing. After printing, the printed construct was cured via free radical polymerization, and alginate was crosslinked by calcium ions. Most importantly, with calcium crosslinking of alginate, mechanical properties of 3D printed hydrogels are greatly improved. Furthermore, these 3D printed hydrogels can serve as ionic conductors, because hydrogels contain large amounts of water that dissolve excess calcium ions. A wearable resistive strain sensor that can quickly and precisely detect human motions like finger bending was fabricated by a 3D printed hydrogel film. These results demonstrate that the conductive, transparent, and stretchable hydrogels are promising candidates as soft wearable electronics for healthcare, robotics and entertainment.