| 1. |
- Asta, Nadia, et al.
(author)
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The Use of Model Cellulose Materials for Studying Molecular Interactions at Cellulose Interfaces
- 2023
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In: ACS Macro Letters. - : American Chemical Society (ACS). - 2161-1653. ; 12, s. 1530-1535
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Journal article (peer-reviewed)abstract
- Despite extensive research on biobased and fiber-based materials, fundamental questions regarding the molecular processes governing fiber-fiber interactions remain unanswered. In this study, we introduce a method to examine and clarify molecular interactions within fiber-fiber joints using precisely characterized model materials, i.e., regenerated cellulose gel beads with nanometer-smooth surfaces. By physically modifying these materials and drying them together to create model joints, we can investigate the mechanisms responsible for joining cellulose surfaces and how this affects adhesion in both dry and wet states through precise separation measurements. The findings reveal a subtle balance in the joint formation, influencing the development of nanometer-sized structures at the contact zone and likely inducing built-in stresses in the interphase. This research illustrates how model materials can be tailored to control interactions between cellulose-rich surfaces, laying the groundwork for future high-resolution studies aimed at creating stiff, ductile, and/or tough joints between cellulose surfaces and to allow for the design of high-performance biobased materials.
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| 2. |
- Cao, Wei, et al.
(author)
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Dual-Cationic Poly(ionic liquid)s Carrying 1,2,4-Triazolium and Imidazolium Moieties : Synthesis and Formation of a Single-Component Porous Membrane
- 2021
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In: ACS Macro Letters. - : American Chemical Society (ACS). - 2161-1653. ; 10:1, s. 161-166
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Journal article (peer-reviewed)abstract
- Both imidazolium and 1,2,4-triazolium cations are important functional moieties widely incorporated as building blocks in poly(ionic liquid)s (PILs). In a classical model, a PIL usually contains either imidazolium or 1,2,4-triazolium in its repeating unit. Herein, via exploiting the slight reactivity difference of alkyl bromide with imidazole and 1,2,4-triazole at room temperature, we synthesized dual-cationic PIL homopolymers carrying both imidazolium and 1,2,4-triazolium moieties in the same repeating unit, that is, an asymmetrically dicationic unit. We investigated their fundamental properties, for example, thermal stability and solubility, as well as their unique function in forming supramolecular porous membranes via a water-initiated phase-separation and cross-linking process. With such knowledge, we identified a water-based fabricate strategy toward air-stable porous membranes from single-component Pits. This study will enrich the design tools and chemical structure library of PILs and expand their application spectrum.
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| 3. |
- Jerlhagen, Åsa, et al.
(author)
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Self-Catalyzed Hydrolysis of Nitrile-Containing RAFT Chain-Transfer Agent and Its Impact upon Polymerization Control of Methacrylic Monomers
- 2024
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In: ACS Macro Letters. - : American Chemical Society (ACS). - 2161-1653. ; 13:5, s. 565-570
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Journal article (peer-reviewed)abstract
- Self-catalyzed hydrolysis upon storage of the common RAFT chain-transfer agent (CTA) 4-cyano-4-[(thiothiopropyl)sulfanyl] pentanoic acid (CTPPA) is confirmed, where the nitrile group is transformed into an amide by catalysis from the adjacent carboxylic acid moiety. The amide-CTA (APP) is found to poorly control molecular weight evolution during polymerization of two methacrylates, methyl methacrylate (MMA) and N,N-(dimethylamino)ethyl methacrylate (DMAEMA), likely due to poor reinitiation speed in the pre-equilibrium. However, when attached to a macromolecule, the impact of this amide moiety becomes insignificant and chain extension proceeds as expected with CTPPA. In light of CTPPA and similarly hydrolyzable CTAs being extensively employed for aqueous polymerizations of methacrylates, these findings highlight the importance of CTA purity when performing RAFT polymerizations.
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| 4. |
- Moreno, Adrian, et al.
(author)
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Urushi as a Green Component for Thermally Curable Colloidal Lignin Particles and Hydrophobic Coatings
- 2023
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In: ACS Macro Letters. - 2161-1653. ; 12:6, s. 759-766
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Journal article (peer-reviewed)abstract
- Colloidal lignin nanoparticles are promising buildingblocks forsustainable functional materials. However, their instability in organicsolvents and aqueous alkali limits their applicability. Current stabilizationmethods require nonrenewable and toxic reagents or tedious workupprocedures. Here we show a method to prepare hybrid nanoparticlesusing only natural components. Urushi, a form of black oriental lacquer,and lignin are coaggregated to form hybrid particles, with Urushiacting as a sustainable component that stabilizes the particles viahydration barrier effect and thermally triggered internal cross-linking.The weight fractions of the two components can be adjusted to achievethe desired level of stabilization. Hybrid particles with Urushi content>25 wt % undergo interparticle cross-linking that produces multifunctionalhydrophobic protective coatings that improve the water resistanceof wood. This approach provides a sustainable and efficient methodfor stabilizing lignin nanoparticles and opens up neoteric possibilitiesfor the development of lignin-based advanced functional materials.
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| 5. |
- Pan, Dong, et al.
(author)
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Alkali-Stable Anion Exchange Membranes Based on Poly(xanthene)
- 2023
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In: ACS Macro Letters. - : American Chemical Society (ACS). - 2161-1653. ; 12:1, s. 20-25
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Journal article (peer-reviewed)abstract
- Poly(xanthene)s (PXs) carrying trimethyl ammonium, methylpiperidinium and quinuclidinium cations were synthesized and studied as a new class of anion exchange membranes (AEMs). The polymers were prepared in a superacid-mediated polyhydroxyalkylation involving 4,4’-biphenol and 1-bromo-3-(trifluoroacetylphenyl)-propane, followed by quaternization reactions with the corresponding amines. The architecture with a rigid PX backbone decorated with cations via flexible alkyl spacer chains resulted in AEMs with high ionic conductivity, thermal and chemical stability. For example, hydroxide conductivities up to 129 mS cm−1 were reached at 80 °C, and all the AEMs showed exceptional alkaline stability with less than 4% ionic loss after treatment in 2 M aq. NaOH at 90 °C during 720 h. Critically, the diaryl ether links of the PX backbone remained intact after the harsh alkaline treatment, as evidenced by both 1H NMR spectroscopy and thermogravimetry. Our combined findings suggest that PX AEMs are viable for application in alkaline fuel cells and electrolyzers.
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