ACS Macro Letters最新文献

Sulfur hexafluoride (SF₆) is widely used in the power industry and significantly contributes to the greenhouse effect, necessitating the development of efficient materials for SF₆ capture, particularly fluorine-containing materials. However, existing fluorine-containing materials often require complex monomers and high synthesis temperatures. Herein, we report the synthesis of a fluorine-functionalized carbazole-based nanoporous organic polymer (CNOP-7) at room temperature, using commercially available 4,4′-bis(9H-carbazole-9-yl)-1,1′-biphenyl and 1,1,1-trifluoroacetone. CNOP-7 contains 14.7% fluorine atoms and exhibits a high specific surface area of 1270 m²·g^–1, demonstrating excellent SF₆ adsorption and separation performance. The SF₆/N₂ selectivity of CNOP-7 reaches 107 at 273 K and 73 at 298 K. Furthermore, dynamic breakthrough experiments confirm that CNOP-7 can efficiently and repeatedly separate SF₆ from SF₆/N₂ mixtures. Molecular simulations reveal the mechanism behind its efficient separation. This work offers fresh perspectives on the development and fabrication of adsorbents for efficient SF₆ sequestration.

Polyrotaxane (PR) is a mechanically interlocked polymer (MIP) utilized as an electrolyte because of its distinctive property of dynamic molecular mobility. While numerous studies have concentrated on modifying external properties to decrease high crystallinity, few have explored the control of intrinsic properties. This study examines the crystalline properties and molecular mobility of PR-based electrolytes, along with their effects on ionic conductivity, by manipulating intrinsic properties. By systematically varying the inclusion ratio, we demonstrate that lower inclusion ratios lead to reduced crystallinity, enhancing molecular mobility. Consequently, 100PRE exhibits decreased crystallinity due to lower aggregation probabilities of α-cyclodextrins (α-CDs), longer T₂ relaxation times (0.215 s), and higher ionic conductivity (3.4 × 10^–3 S cm^–1 at 25 °C).

Hybrid organic-inorganic nanostructures offer significant potential for developing advanced functional materials with numerous technological applications. However, the fabrication process is often tedious and time-consuming. This study presents a facile method for fabricating block copolymer-based photonic microspheres incorporating plasmonic gold nanoparticles. Specifically, the confined self-assembly of poly(styrene)-b-poly(2-vinylpyridine) in emulsion droplets allows the formation of spherical, noniridescent, concentric lamellar structures, i.e., onion-like particles that are subsequently infiltrated with gold salt. Using ethanol as a preferential solvent allows the loading of metal ions exclusively into the poly(2-vinylpyridine) domains, which are subsequently reduced, leading to the in situ, spatially controlled formation of gold nanoparticles. The hybrid structures exhibit a well-defined photonic bandgap and plasmonic resonance at low gold concentrations. These results demonstrate the feasibility of fabricating optically active photonic structures comprising metal nanoparticles in a block copolymer array via a simple two-step fabrication process.

The self-assembly of sequence-defined polymers (SDPs) enables the formation of a diverse array of nanostructures; however, the construction of complex hierarchical structures via thermal annealing from SDPs remains relatively unexplored. In this study, two series of oligourethanes, 2Cit-pB_n-OH and 2Cit-mB_n-OH, were synthesized to investigate their thermal annealing behaviors. Nanorod clusters were generated from 2Cit-pB₆-OH in a mixture of 1,4-dioxane and toluene, whereas 2Cit-pB₈-OH formed nanosheets after thermal annealing. Upon modifying the structure of the repeating units, 2Cit-mB₆-OH self-assembled into ultrathin nanosheets, transitioning from nanospheres after thermal annealing in a mixture of isopropanol and cyclohexane, while “flower” micelles were produced from 2Cit-mB₈-OH. Interestingly, when isopropanol was replaced with a mixture of isopropanol and tetrahydrofuran (THF), uniform nanotubes were generated by 2Cit-mB₆-OH under the same thermal annealing conditions. Additionally, a discrete amphiphile (2Cit-mB₄-(S)DPEG) was synthesized, leading to the formation of uniform nanosheets in aqueous solution after thermal annealing. This work highlights the significant effects of sequence and repeating unit structure of SDPs on their self-assembly behaviors and presents a novel strategy for the controlled fabrication of unique nanostructures from SDPs.

This study presents a novel approach utilizing total internal reflection microscopy (TIRM) to effectively characterize the swelling and collapse of polymer brushes in aqueous solutions. Zwitterionic poly(carboxybetaine methacrylate) (PCBMA) and nonionic poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) brushes are chosen as model systems. By investigation of an intriguing theory-experiment discrepancy observed during the measurement of near-wall hindered diffusion, valuable insights into the compressibility of polymer brushes are obtained, revealing their conformational information in aqueous solution. The results demonstrate that zwitterionic PCBMA brushes exhibit minimal antipolyelectrolyte effects in 0.1-10 mM NaCl solution but undergo significant swelling with increasing pH. On the other hand, nonionic POEGMA brushes exhibit similar responses to ionic strength as weak polyelectrolyte brushes. These unexpected findings enhance our understanding of polymer brushes beyond classical theories. The TIRM-based approach proves to be effective for characterizing polymer brushes and other soft nanomaterials.

We report the mechanical performance and chemical recycling advantages of implementing alkyl-substituted poly(ε-caprolactones) (PCLs) as soft segments in thermoplastic poly(urethane-urea) (TPUU) materials. Poly(4-methylcaprolactone) (P4MCL) and poly(4-propylcaprolactone) (P4PrCL) were prepared, reacted with isophorone diisocyanate, and chain-extended with water to form TPUUs. The resulting materials’ tensile properties were similar or superior to a commercially available polyester thermoplastic poly(urethane) and had superior elastic recovery properties compared to a PCL analogue due to the noncrystalline nature of P4MCL and P4PrCL. Additionally, monomers were recovered from the TPUU materials in high yields via ring-closing depolymerization using a reactive distillation approach at an elevated temperature and a reduced pressure (240–260 °C, 25–140 mTorr) with zinc chloride (ZnCl₂) as the catalyst. The thermodynamics of polymerization were estimated using Van’t Hoff analyses for 4MCL and 4PrCL; these results indicated that the propyl group in 4PrCL results in a lower practical ceiling temperature (T_c) for P4PrCL.