| 1. |
- Hafeez, Ainy, et al.
(författare)
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Synergetic Effect of Packed-bed Corona-DBD Plasma Micro-Reactor and Photocatalysis for Organic Pollutant Degradation
- 2021
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Ingår i: Separation and Purification Technology. - : Elsevier. - 1383-5866 .- 1873-3794. ; 269
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Tidskriftsartikel (refereegranskat)abstract
- A packed-bed Corona-DBD hybrid plasma micro-reactor is coupled with a novel heterogeneous photocatalyst-AgFeO2/CNTs/TiO2 for methyl orange degradation. The corona nature of the plasma produces a high concentration of active species, yet maintaining a homogeneous discharge owing to the dielectric barrier nature of the reactor. The submicron channels in the plasma reactor created by glass beads increased dielectric strength and simultaneously produced high energy streamers, which increased the ozone generation by 24%. The AgFeO2/CNTs/TiO2 photocatalyst gave stretched adsorption edge (400-500 nm), reduced bandgap energy (2.3 eV), facilitated degradation under visible light, and provided the additional advantage of the Fenton process, leading to the OH. formation. The three reaction systems were investigated and compared for MO degradation-photocatalysis, plasma reactor and integrated plasma photocatalysis reactor which gave 1.2%, 50.8%, and 95% removal in 2 minutes respectively. The solution pH, dosage, and loading of AgFeO2 in photocatalyst was investigated. The integrated plasma photocatalysis gave 95% degradation of 250 ml solution of 30 ppm methyl orange at pH 3 with 0.5 g/l of 2.5% AgFeO2/CNTs/TiO2 photocatalysis in 2 minutes. The integrated plasma photocatalysis reactor increased the number density of active species, particularly, OH. in wastewater which makes it a good choice for azo dyes degradation.
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| 2. |
- Chen, Yujie, et al.
(författare)
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A gradient-distributed liquid-metal hydrogel capable of tunable actuation
- 2021
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 421, s. 127762-
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Tidskriftsartikel (refereegranskat)abstract
- Although thermoresponsive hydrogels have numerous applications that range from soft robots, biomedical engineering, and actuators to sensors for artificial muscles, the existing hydrogel actuators undergo only unidirectional deformation under a single thermal stimulus and suffer from slow actuation and unstable interfacial adhesion in multiple layers. Herein, hydrogels containing gradient-distributed polydopamine-coated eutectic gallium-indium (PDA-EGaIn) nanodroplets in a poly(N-isopropylacrylamide) (PNIPAM) matrix and thus featuring a gradient distribution of thermal conductivity and an increased barrier towards water loss are shown to be capable of a rapid and tuneable thermoresponse. Notably, whereas hydrogels with a low content of PDAEGaIn undergo rapid one-way bending under a single thermal (45 degrees C) stimulus, those with a high content of PDAEGaIn undergo sequential bidirectional (bending) actuation. The ability of these hydrogels to undergo fast and tuneable actuation under a single thermal stimulus makes them suitable for use in grab-release instruments and soft robots.
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| 3. |
- Chen, Yujie, et al.
(författare)
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Shape-Memory Polymeric Artificial Muscles : Mechanisms, Applications and Challenges
- 2020
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Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 25:18
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Forskningsöversikt (refereegranskat)abstract
- Shape-memory materials are smart materials that can remember an original shape and return to their unique state from a deformed secondary shape in the presence of an appropriate stimulus. This property allows these materials to be used as shape-memory artificial muscles, which form a subclass of artificial muscles. The shape-memory artificial muscles are fabricated from shape-memory polymers (SMPs) by twist insertion, shape fixation via T(m)or T-g, or by liquid crystal elastomers (LCEs). The prepared SMP artificial muscles can be used in a wide range of applications, from biomimetic and soft robotics to actuators, because they can be operated without sophisticated linkage design and can achieve complex final shapes. Recently, significant achievements have been made in fabrication, modelling, and manipulation of SMP-based artificial muscles. This paper presents a review of the recent progress in shape-memory polymer-based artificial muscles. Here we focus on the mechanisms of SMPs, applications of SMPs as artificial muscles, and the challenges they face concerning actuation. While shape-memory behavior has been demonstrated in several stimulated environments, our focus is on thermal-, photo-, and electrical-actuated SMP artificial muscles.
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| 4. |
- Rehman, Hafeez Ur, et al.
(författare)
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High-cycle-life and high-loading copolymer network with potential application as a soft actuator
- 2019
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Ingår i: Materials & design. - : ELSEVIER SCI LTD. - 0264-1275 .- 1873-4197. ; 182
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Tidskriftsartikel (refereegranskat)abstract
- Thermo-responsive polymer materials ate appealing in emerging fields including soft robotics, artificial muscles, and actuators. However, realising a single smart polymer material that can achieve immense strain, fast actuation, and high loading remains a challenge. We attempted to address these limitations by fabricating a thermo-responsive copolymer network structure of poly(urethane-caprolactone-siloxane). The relative concentrations of these precursors were adjusted to realise a high mechanical strength of >= 17 MPa, 100% shape fixation, and a quick shape recovery time of <= 15 s. Experimental results revealed that the soft segments largely determines the extensibility and crystallinity of the copolymer material. The thermal gradient of the soft part enables the copolymer to self-heal during shape recovery. The copolymer network was applied to a load lifting device as an artificial muscle and was able to lift 200 times its weight with a short response time of <5 s and maximum power density that was half that of mammalian skeletal muscles. With its fast actuation, high loading, and self-healing abilities, the developed therrno-activated smart copolymer material is potentially applicable to a wide range of fields such as soft robotics, biomimetic devices, and prosthetics.
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| 5. |
- Rehman, Hafeez Ur, et al.
(författare)
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Self-Healing Shape Memory PUPCL Copolymer with High Cycle Life
- 2018
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Ingår i: Advanced Functional Materials. - : WILEY-V C H VERLAG GMBH. - 1616-301X .- 1616-3028. ; 28:7
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Tidskriftsartikel (refereegranskat)abstract
- New polyurethane-based polycaprolactone copolymer networks, with shape recovery properties, are presented here. Once deformed at ambient temperature, they show 100% shape fixation until heated above the melting point, where they recover the initial shape within 22 s. In contrast to current shape memory materials, the new materials do not require deformation at elevated temperature. The stable polymer structure of polyurethane yields a copolymer network that has strength of 10 MPa with an elongation at break of 35%. The copolymer networks are self-healing at a slightly elevated temperature (70 degrees C) without any external force, which is required for existing self-healing materials. This allows for the new materials to have a long life of repeated healing cycles. The presented copolymers show features that are promising for applications as temperature sensors and activating elements.
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| 6. |
- Rehman, Hafeez Ur, et al.
(författare)
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Stretchable, Strong, Recyclable Helicide Elastomer Based on Dynamic Covalent Interactions
- 2023
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 15:39, s. 46280-46291
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Tidskriftsartikel (refereegranskat)abstract
- Current methods for making and disposing synthetic polymers have been widely pursued and are largely unsustainable. As a part of the solution, the reversible nature of dynamic covalent bonds emerges as an extraordinarily diverse and valuable feature in the development of exotic molecules and extended structures. With these bonds, it should be possible to construct recyclable and mechanically interlocked molecular structures using relatively simple precursors with preorganized geometries. A new helicide-based elastomer network is developed here with self-healing, recycling, and degradation features using a similar concept. The best self-healing performance (100%) was noted over 10-20 min, with various H2O, HCl, and NaOH solutions that delivered mechanical properties in the 1-1.4 MPa range. For hydrolytic degradation, the parameters are defined based on the type of binding, the pH of the solutions, and the copolymer network, which endowed a degradation time of approximately 4-11 h for each prepared sample. However, due to the reversible nature of the dynamic bonds, the material showed good recyclable mechanical properties compared to the pristine samples after five consecutive cycles, which meet the requirements of recyclable materials and recyclable packaging.
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