| 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. |
- Li, Guohui, et al.
(författare)
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Localized Bound Multiexcitons in Engineered Quasi-2D Perovskites Grains at Room Temperature for Efficient Lasers
- 2023
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 35:20
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Tidskriftsartikel (refereegranskat)abstract
- Reducing the excitation threshold to minimize the Joule heating is critical for the realization of perovskite laser diodes. Although bound excitons are promising for low threshold laser, how to generate them at room temperature for laser applications is still unclear in quasi-2D perovskite-based devices. In this work, via engineering quasi-2D perovskite PEA2(CH3NH3)n-1PbnBr3n+1 microscopic grains by the anti-solvent method, room-temperature multiexciton radiative recombination is successfully demonstrated at a remarkably low pump density of 0.97 µJ cm−2, which is only one-fourth of that required in 2D CdSe nanosheets. In addition, the well-defined translational momentum in quasi-2D perovskite grains can restrict the Auger recombination which is detrimental to radiative emission. Furthermore, the quasi-2D perovskite grains are favorable for increasing binding energies of excitons and biexcitons and so as the related radiative recombination. Consequently, the prepared phase quasi-2D perovskite film renders a threshold of room-temperature stimulated emission as low as 13.7 µJ cm−2, reduced by 58.6% relative to the amorphous counterpart with larger grains. The findings in this work are expected to facilitate the development of solution-processable perovskite multiexcitonic laser diodes.
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| 3. |
- Li, Junhao, et al.
(författare)
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Full-color enhanced second harmonic generation using rainbow trapping in ultrathin hyperbolic metamaterials
- 2021
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Though metamaterials enhance nonlinear light-matter interactions due to their resonant features, these materials typically show a narrow spectral bandwidth. Here, the authors report broadband enhanced second-harmonic generation in patterned multilayer hyperbolic metamaterial arrays. Metasurfaces have provided a promising approach to enhance the nonlinearity at subwavelength scale, but usually suffer from a narrow bandwidth as imposed by sharp resonant features. Here, we counterintuitively report a broadband, enhanced second-harmonic generation, in nanopatterned hyperbolic metamaterials. The nanopatterning allows the direct access of the mode with large momentum, rendering the rainbow light trapping, i.e. slow light in a broad frequency, and thus enhancing the local field intensity for boosted nonlinear light-matter interactions. For a proof-of-concept demonstration, we fabricated a nanostructured Au/ZnO multilayer, and enhanced second harmonic generation can be observed within the visible wavelength range (400-650 nm). The enhancement factor is over 50 within the wavelength range of 470-650 nm, and a maximum conversion efficiency of 1.13x10(-6) is obtained with a pump power of only 8.80 mW. Our results herein offer an effective and robust approach towards the broadband metasurface-based nonlinear devices for various important technologies.
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| 4. |
- 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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| 5. |
- Marcotte, Harold, et al.
(författare)
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Conversion of monoclonal IgG to dimeric and secretory IgA restores neutralizing ability and prevents Infection of Omicron lineages
- 2024
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 121:3
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Tidskriftsartikel (refereegranskat)abstract
- The emergence of Omicron lineages and descendent subvariants continues to present a severe threat to the effectiveness of vaccines and therapeutic antibodies. We have previ- ously suggested that an insufficient mucosal immunoglobulin A (IgA) response induced by the mRNA vaccines is associated with a surge in breakthrough infections. Here, we further show that the intramuscular mRNA and/or inactivated vaccines cannot suffi- ciently boost the mucosal secretory IgA response in uninfected individuals, particu- larly against the Omicron variant. We thus engineered and characterized recombinant monomeric, dimeric, and secretory IgAl antibodies derived from four neutralizing IgG monoclonal antibodies (mAbs 01A05, rmAb23, DXP-604, and XG014) targeting the receptor-binding domain of the spike protein. Compared to their parental IgG antibod- ies, dimeric and secretory IgAl antibodies showed a higher neutralizing activity against different variants of concern (VOCs), in part due to an increased avidity. Importantly, the dimeric or secretory IgAl form of the DXP-604 antibody significantly outperformed its parental IgG antibody, and neutralized the Omicron lineages BA.1, BA.2, and BA.4/5 with a 25- to 75-fold increase in potency. In human angiotensin converting enzyme 2 (ACE2) transgenic mice, a single intranasal dose of the dimeric IgA DXP-604 conferred prophylactic and therapeutic protection against Omicron BA.5. Thus, dimeric or secre- tory IgA delivered by nasal administration may potentially be exploited for the treatment Iand prevention of Omicron infection, thereby providing an alternative tool for combating immune evasion by the current circulating subvariants and, potentially, future VOCs.
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| 6. |
- Wang, Lei, et al.
(författare)
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Coumarin derivative trigger controlled photo-healing of ion gels and photo-controlled reversible adhesiveness
- 2021
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Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 144
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Tidskriftsartikel (refereegranskat)abstract
- Fabrication strategies for photo-responsive ion gels have attracted attention owing to their precise spatial and temporal control with predetermined responses to light stimuli. In this work, a reversible light-driven method was introduced to devise photo-responsive ion gels by harnessing coumarin-based building blocks under 365 nm irradiation. A series of random copolymers composed of N, N-dimethylacrylamide (DMA) and 7-(2′-methacryloyloxyethoxy)–4-methylcoumarin (MAOEMC), namely P(DMA-r-MAOEMC), were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization with sufficient molecular weight (≈100 kDa). The coumarin moieties in those polymers exhibited a reversible photo-induced dimerization and photocleavage behavior in 1-ethyl-3-methylimidazolium bis (trifluoromethylsufonyl) imide ([C2mim][NTf2]). Those polymers - ionic liquid system at high polymer concentration (20 wt%) under suitable wavelength UV light irradiation led to sol–gel transition, which could be functionalized as photo-healable material and photo-controlled adhesion agents. Notably, the photo-controlled adhesiveness was reversible and can be mediated from 1.2 MPa to 0.2 MPa. This work opens new avenues to develop multifunctional ion gels using dynamic covalent bonds.
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| 7. |
- Wang, Lei, et al.
(författare)
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Photo-healable ion gel with high mechanical property, fatigue resistance and shear resistance using a coumarin group containing diblock copolymer in an ionic liquid
- 2022
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Ingår i: European Polymer Journal. - : Elsevier. - 0014-3057 .- 1873-1945. ; 165
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Tidskriftsartikel (refereegranskat)abstract
- Ion gels, polymer networks swollen with ionic liquid (IL), are ideal materials for application in flexible electronic devices. It remains a challenge to fabricate an ion gel with photo-healing, high mechanical properties, fatigue resistance and shear resistance. Herein, a well-defined diblock copolymer polystyrene-b-poly(methyl acrylate-r-7-(2′-methacryloyloyloxyethoxy)-4-methylcoumarin) (PS-b-P(DMA-r-MAOEMC), brief name: SMM, PS: IL-phobic segment and P(DMA-r-MAOEMC): IL-philic segment) was synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. For comparison, a random copolymer P(DMA-r-MAOEMC) (MM) also be prepared. In dilute solution, the SMM can form spherical micelles with PS-core surrounded by P(DMA-r-MAOEMC) corona chains in an IL, 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfone)amide ([C2mim][NTf2]). In a suitable polymer concentration, the SMM and MM can form ion gels in [C2mim][NTf2] under 365 nm UV light irradiation through photo-dimerization of coumarin groups in corona MM polymer chains of spherical micelles and photo-dimerization of coumarin groups in MM random polymer chains, respectively. Compared with the MM ion gel, the SMM ion gel has high mechanical properties, shear resistance and relatively high fatigue resistance. Under 254 nm UV light irradiation, photo-induced gel to jammed micelles transition for the SMM ion gel and photo-induced gel to sol transition for the MM ion gel occur due to photo-cleavage of dimer in polymer chains. Photo-induced jammed micelles - gel transition for the SMM ion gel and photo-induced sol - gel transition for the MM ion gel are reversible by alternating 365 nm and 254 nm UV light irradiation, whereby photo-healable materials can be fabricated. Compared to the MM ion gel, the SMM ion gel has high photo-healing efficiency. The electrochemical property of the SMM ion gel can be recovered completely after photo-healing.
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| 8. |
- Zhao, Kefan, et al.
(författare)
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High-Quality Solution-Processed Quasi-2D Perovskite for Low-Threshold Lasers
- 2024
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Ingår i: ACS Applied Materials and Interfaces. - 1944-8244. ; 16:17, s. 22361-22368
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Tidskriftsartikel (refereegranskat)abstract
- Spin-coated quasi-two-dimensional halide perovskite films, which exhibit superior optoelectronic properties and environmental stability, have recently been extensively studied for lasers. Crystallinity is of great importance for the laser performance. Although some parameters related to the spin-coating process have been studied, the in-depth understanding and effective control of the acceleration rate on two-dimensional perovskite crystallization during spin-coating are still unknown. Here we investigate the effect of solvent evaporation on the microstructure of the final perovskite films during the spin-coating process. The crystallization quality of the film can be significantly improved by controlling solvent evaporation. As a result, the prepared quasi-2D perovskite film exhibits a stimulated emission threshold (pump: 343 nm, 6 kHz, 290 fs) of 550 nm as low as 16.2 μJ/cm2. Transient absorption characterization shows that the radiative biexciton recombination time is reduced from 738.5 to 438.3 ps, benefiting from the improved crystallinity. The faster biexciton recombination significantly enhanced the photoluminescence efficiency, which is critical for population inversion. This work could contribute to the development of low-threshold lasers.
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