| 1. |
- Lan, Xiaoyu, et al.
(författare)
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Self-Assembly of Diblock Copolymers Containing Thermo- and Photoresponsive Lower Critical Solution Temperature Phase Behavior Polymer with Tunable Assembly Temperature in an Ionic Liquid Mixture
- 2019
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:6, s. 11229-11236
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Tidskriftsartikel (refereegranskat)abstract
- This work prepared a type of diblock copolymer with thermo- and photosensitivity in ionic liquids (ILs). P(N,N-dimethylacrylamide) (compatible with ILs) was prepared as one segment, while butyl acrylate (BA) and 4-phenylazophenylmethacrylate (AzoMA) were copolymerized as another segment P(AzoMA-r-BA) with stimuli responsiveness. The diblock copolymer showed tunable lower critical micellization temperature (LCMT) in two mixed imidazole ionic liquids. The value of LCMT depends on not only the conformation status of the azo group in copolymers but also the azo group content in copolymers and mixed ratio of ionic liquids. Based on this tunable LCMT, photoinduced micellization/demicellization can be achieved near room temperature by alternate irradiation with visible and ultraviolet light, and it is totally reversible.
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| 2. |
- Ma, Xiaofeng, et al.
(författare)
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Photo-induced Actuator using Temperature and Light Dual Responsive Azobenzene Containing Ion Gel in Ionic Liquid
- 2020
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Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 123
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Tidskriftsartikel (refereegranskat)abstract
- A series of well-defined random copolymers comprising butyl acrylate (BA) and 4-phenylazophenylmethacrylate (AzoMA) (P(AzoMA-r-BA)) are prepared successfully by reversible addition fragmentation chain transfer (RAFT) polymerization. P(AzoMA-r-BA)s show LCST-type phase transition in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfone)amide ([C4mim][NTf2]). LCST depends on the photoisomerization state of azobenzene, as well as on the AzoMA composition in the random copolymers. LCST of (P(cis-AzoMA-r-BA) is significantly higher than that of P(trans-AzoMA-r-BA), because cis-AzoMA and trans-AzoMA behave as solvato-philic and solvato-phobic comonomer, respectively. At a bistable temperature, photo-induced phase separation is completely reversible. Secondly, based on this phenomenon, a thermo- / photo- responsive ion gel (BA-AzoMA ion gel) can be prepared by free radical polymerization of BA and AzoMA using ethylene glycol dimethacrylate (EGDMA) as crosslinker in [C4mim][NTf2]. BA-AzoMA ion gel shows high temperature contraction and low temperature expansion behavior, due to LCST-type phase behavior of polymer system consisting of AzoMA and BA. Contraction temperature of BA-AzoMA ion gel depends on photoisomerization state of the azobenzene group in polymers. At a bistable temperature, photo-induced expansion-contraction is reversible. Finally, a Photo-induced actuator can be realized using BA-AzoMA ion gel at suitable temperatures, featuring reversible bending by alternate irradiating with visible and UV light. The bending behavior is also demonstrated.
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| 3. |
- Lu, Xinyu, et al.
(författare)
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A review on lignin antioxidants: Their sources, isolations, antioxidant activities and various applications
- 2022
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier. - 0141-8130 .- 1879-0003. ; 210, s. 716-741
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Forskningsöversikt (refereegranskat)abstract
- Lignin, a biopolymer obtained from agricultural/forestry residues or paper pulping wastewater, is rich in aromatic structure, which is central to its adoption as a candidate to natural antioxidants. Through insight into its structural features from biomass, different functional groups would influence lignin antioxidant activity, wherein phenolic content is the most important factor, hence massive studies have focused on its improvement via different pretreatments and post-processing methods. Besides, lignin nanoparticles and chemical modifications are also efficient methods to improve antioxidant activity via increasing free content and decreasing bond dissociation enthalpy of phenolic hydroxyl. Lignin samples exhibit comparable radicals scavenging ability to commercial ones, showing their potential as renewable alternatives of synthesized antioxidants. Besides, their applications have also been discussed, which demonstrates lignin potential as an inexpensive antioxidant additive and consequent improvements on multiple functionalities. This review is dedicated to summarize lignin antioxidants extracted from biomass resources, methods to improve their antioxidant activity and their applications, which is beneficial for realizing lignin valorization.
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| 4. |
- Lu, Xinyu, et al.
(författare)
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A review on the synthesis of MXenes and their lubrication performance and mechanisms
- 2023
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Ingår i: Tribology International. - : Elsevier. - 0301-679X .- 1879-2464. ; 179
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Forskningsöversikt (refereegranskat)abstract
- MXenes (MXs), as an emerging 2D family of transition metal carbides and nitrides, have been considered as new candidates for solid lubrication/lubricant additives due to their mono-layered graphene-like structure with similar mechanical properties, abundant surface terminations (i.e., -O, -OH, -F), relatively low shear strength and inherent self-lubrication ability. In this review, we introduced MXs’ synthesis and their lubrication performance and mechanisms. Typically, pure MXs and MXs-based composites like MXs/polymers, MXs/graphene (MoS2) or MXs/metals (metal oxide) were used as reinforcement materials to form protective coatings with excellent mechanical properties and solid lubrication performance. As liquid lubricant additives, MXs can be used as water-/oil-based lubricant additives, and exhibit improved friction and wear. At the same time, chemically functionalized MXs with better dispersibility and compatibility were introduced as the improved oil-based lubricant additives. Some parameters (such as MXs’ structural effects and working conditions) affecting MXs’ lubrication performance, and the lubrication mechanisms (such as the formation of tribofilm, the hydrophilicity-/interlayer-dependent lubrication mechanism and adsorption effect) were all discussed. Finally, some future perspectives for MXs’ lubrication were proposed at the end of this review.
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| 5. |
- Mu, Liwen, et al.
(författare)
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Achieving High Value Utilization of Bio-oil from Lignin Targeting for Advanced Lubrication
- 2021
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Ingår i: ES Materials & Manufacturing. - : Engineered Science Publisher. - 2578-0611 .- 2578-062X. ; 11, s. 72-80
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Tidskriftsartikel (refereegranskat)abstract
- High-value utilization of biomass has been driven by increasingly growing industrial demands. Herein, we offer a strategy composed of depolymerization and esterification reaction of lignin to transfer to bio-oil with high liquid yield (79.75~85.25%), which is demonstrated as a high performance lubricant. Overall, the bio-oil has the excellent lubrication properties, where a significant wear reduction of 97.6% was observed as compared with polyethylene glycol 200. Meanwhile, the more ether and less acid in bio-oil could improve the anti-wear properties. This work provides a new application of utilizing lignin in advanced lubrication systems.
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