scholarly journals Rapid uniaxial actuation of layered bacterial cellulose/poly(N-isopropylacrylamide) composite hydrogel with high mechanical strength

RSC Advances ◽  
2018 ◽  
Vol 8 (23) ◽  
pp. 12608-12613 ◽  
Author(s):  
Qidong Wang ◽  
Taka-Aki Asoh ◽  
Hiroshi Uyama

Anisotropic thermo-sensitive composite hydrogel based on bacterial cellulose was prepared by in situ polymerization, which could swell and deswell uniaxially.

RSC Advances ◽  
2017 ◽  
Vol 7 (3) ◽  
pp. 1513-1519 ◽  
Author(s):  
Lanlan Li ◽  
Ruyi Jiang ◽  
Jinxing Chen ◽  
Mozhen Wang ◽  
Xuewu Ge

Novel nanoparticles-reinforced polyacrylamide-based hydrogel with high mechanical strength can be prepared through the RAFT polymerization of acrylamide and ethylene glycol dimethacrylate in the presence of particulate macro-RAFT agents in water.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shennan Wang ◽  
Kai Li ◽  
Qi Zhou

Abstract A delignified wood template with hydrophilic characteristics and high porosity was obtained by removal of lignin. Gelatin was infiltrated into the delignified wood and further crosslinked with a natural crosslinker genipin to form hydrogels. The composite hydrogels showed high mechanical strength under compression and low swelling in physiological condition. The effect of genipin concentrations (1, 50 and 100 mM) on structure and properties of the composite hydrogels were studied. A porous honeycomb structure with tunable pore size and porosity was observed in the freeze-dried composite hydrogels. High elastic modulus of 11.82 ± 1.51 MPa and high compressive yield stress of 689.3 ± 34.9 kPa were achieved for the composite hydrogel with a water content as high as 81%. The equilibrium water uptake of the freeze-dried hydrogel in phosphate buffered saline at 37 °C was as low as 407.5%. These enables the delignified wood structure an excellent template in composite hydrogel preparation by using infiltration and in-situ synthesis, particularly when high mechanical strength and stiffness are desired.


Author(s):  
Chao Wang ◽  
Guanlin Zhou ◽  
Xiaosong Wang ◽  
Jinguo Liu ◽  
Dong Li ◽  
...  

2010 ◽  
Vol 63 ◽  
pp. 170-174 ◽  
Author(s):  
Rodrigo Mende Mesquita ◽  
Ana Helena Almeida Bressiani

High performance porous structural ceramics have been widely studied. Silicon nitride is an interesting material for this application because bodies with high mechanical strength, achieved as a result of “in situ” anisotropic grain grown, can be obtained. In this study, Si3N4 bodies with different porosity related aspects (percentage, morphology, etc.) are made using the sacrificing template method, by changing the percentage (vol%) and the drying method of the mixture as well as the sintering time. The porosity, apparent density (Archimedes method), microstructure (SEM) and the mechanical strength (in compression) of these bodies were determined. It was thus possible to relate the type and amount of starch with the porosity and mechanical properties of the bodies.


Author(s):  
Viktor V. Revin ◽  
Natalia B. Nazarova ◽  
Ekaterina E. Tsareva ◽  
Elena V. Liyaskina ◽  
Vadim D. Revin ◽  
...  

Aerogels have gained significant interest in recent decades because of their unique properties such as high porosity, low density, high surface area, and excellent heat and noise insulation. However, their high cost and low mechanical strength limit their practical application. We developed appropriate conditions to produce aerogels with controlled density, high mechanical strength, and thermal characteristics from bacterial cellulose (BC) synthesized by the strain Komagataeibacter sucrofermentans H-110. Aerogels produced using TEMPO oxidized BC (OBC) exhibited high mechanical strength and lower shrinkage than those from native bacterial cellulose (NBC). Compared to the NBC, the use of TEMPO-oxidized BC with oxidation degrees (OD) of 1.44 and 3.04% led to the reduction of shrinkage of the aerogels from 41.02 to 17.08%. The strength of the aerogel produced from the TEMPO-oxidized BC with an oxidation degree of 1.44% was twice that of the aerogel produced from NBC. The addition of Mg2+ at concentrations of 20 and 40 mM during the preparation of the aerogels increased the strength of the aerogels by 4.9 times. The combined use of TEMPO-oxidized BC and Mg2+ allowed pore size reduction from 1,375 to 197.4 μm on the outer part of the aerogels, thereby decreasing the thermal conductivity coefficient from 0.036 to 0.0176 W/(m•K). Furthermore, novel biocomposites prepared from the aerogels based on NBC and OBC and sodium fusidate, which have high antibiotic activity against Staphylococcus aureus, were obtained. Owing to their antibacterial properties, these aerogels can be used as functional biomaterials in a wide range of applications such as in tissue engineering and fabrication of wound dressing materials.


Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1112 ◽  
Author(s):  
Yanqin Wang ◽  
Yanan Xue ◽  
Jinghui Wang ◽  
Yaping Zhu ◽  
Yu Zhu ◽  
...  

In this work, to obtain a novel composite hydrogel with high mechanical strength, fluorescence and degradable behavior for bone tissue engineering, we prepare a nanofiller and double-network (DN) structure co-enhanced carbon dots/hydroxyapatite/poly (vinyl alcohol) (CDs/HA/PVA) DN hydrogel. The composite hydrogels are fabricated by a combination of two fabrication techniques including chemical copolymerization and freezing‒thawing cycles, and further characterized by FTIR, XRD, etc. Additional investigations focus on the mechanical properties of the hydrogel with varying mass ratios of CDs to PVA, HA to PVA and different numbers of freezing/thawing cycles. The results show that the as-prepared CDs3.0/HA0.6/PVA DN9 hydrogel has optimized compression properties (Compression strength = 3.462 MPa, Young’s modulus = 4.5 kPa). This is mainly caused by the synergism effect of the nanofiller and chemical and physical co-crosslinking. The water content and swelling ratio of the CDs/HA/PVA SN and DN gels are also systematically investigated to reveal the relationship of their microstructural features and mechanical behavior. In addition, in vitro degradation tests of the CDs/HA/PVA DN hydrogel show that the DN hydrogels have a prominent degradable behavior. So, they have potential to be used as high-strength, self-tracing bone substitutes in the biomedical engineering field.


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