分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-05-02
Gao, GR [Gao, Guorong][ 1 ]
Du, GL [Du, Gaolai][ 1 ]
Cheng, YJ [Cheng, Yajun][ 1 ]
Fu, J [Fu, Jun][ 1 ]
摘要： Polymer hydrogels with superior strength and toughness are potential candidate materials for the replacement or engineering of load-bearing tissues. This manuscript reports novel tough nanocomposite hydrogels with an unusual energy dissipation mechanism based on both covalent and physical interactions between clay nanorods and polymer chains. Attapulgite (ATP) nanorods grafted with vinyl groups on the surface served as macro-crosslinkers to copolymerize with 2-acrylamido-2- methylpropane-sulfonic acid (AMPS) to form an initial nanocomposite network, which subsequently hosted the polymerization of acrylamide (AAm) monomers to generate a novel nanocomposite double network (DN) hydrogel. The morphology, swelling behavior and compressive properties of the ATP- grafted DN hydrogels were investigated as a function of ATP content (CATP), in comparison with the ATP-filled DN gels. With a clay content between 0.1 wt% and 1.0 wt%, the nanocomposite hydrogels did not fracture up to a compressive strain of 98%, exhibiting an initial modulus (E) up to 0.36 MPa, a compressive strength higher than 65.7 MPa, and a work to fracture (or fracture energy) higher than 2.6 MJ m 3, in comparison to 0.19 MPa, 18.6 MPa, and 1.1 MJ m 3 for the conventional DN gels. Cyclic loading–unloading tests showed abnormal residual energy dissipation even though the rigid PAMPS network had fractured. Such viscous energy dissipation decayed during cyclic loading, and could be restored depending on time and temperature. This is related to the reversible desorption–re-adsorption of polymer chains from the clay surface. Possible reinforcing and fracture mechanisms are discussed.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-05-02
Du, GL [Du, Gaolai][ 1 ]
Gao, GR [Gao, Guorong][ 1 ]
Hou, RX [Hou, Ruixia][ 1 ]
Cheng, YJ [Cheng, Yajun][ 1 ]
Chen, T [Chen, Tao][ 1 ]
Fu, J [Fu, Jun][ 1 ]
Fei, B [Fei, Bin][ 2 ]
摘要： Supertough biomimetic hydrogels have been fabricated through in situ synthesis and guided assembling of positively charged conjugated polymer belts by using a parent poly(2-acrylamido-2-methylpropanesulfonic acid)/poly- (acrylamide) double network (PAMPS/PAAm DN) gel template. The inter- penetrating structures of the poly(3,4-ethylenedioxythiophene) (PEDOT) belt mesh and PAMPS/PAAm host network have been confirmed by SEM, CLSM, and Raman spectroscopy. The presence of PEDOT belts improves the Young’s modulus, compressive strength, and toughness of the biomimetic (BM) hydrogels, in comparison to the parent DN gels. Cyclic tensile (300% strain) and compressive (even 90% strain) loadings demonstrate extraordinary fatigue resistance of these BM gels. Upon ten cycles, the compressive toughness remained about 1000 J m−2, which is comparable to that of articular cartilage. The internal fracture behavior and fatigue resistance of these biomimetic interpenetrating hydrogels are further investigated. These extremely tough and fatigue resistant BM hydrogels may find applications as promising substitutes for load-bearing tissues.
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