Polymer Chemistry最新文献

Dibenzobarrelene-based N-heterocyclic carbenes (NHCs) offer tunable steric and electronic properties, making them attractive ligands for Pd catalysis. Herein, we report a family of “large-but-flexible” Pd-NHC precatalysts that enable room-temperature Suzuki–Miyaura polycondensations (SMPs) of sterically hindered and electronically challenging aryl dichlorides. Key features include 2,6-diethylphenyl-substituted NHCs and 3-chloropyridine, which cooperatively promote C–Cl activation. Structural and variable-temperature-NMR analyses reveal suppressed C_Ar–N bond rotation and a conformationally adaptive ligand environment. The system affords high-molecular-weight π-conjugated polymers with broad monomer scope and good solubility. Significantly, it achieves electrophile-selective coupling of aryl chlorides to construct sequence-defined polymers, offering a more practical alternative to traditional nucleophile-based strategies. Mechanistic studies suggest a dynamic ligand exchange equilibrium that stabilizes the active Pd(0) species. These findings establish a robust and versatile platform for low-temperature polycondensation of aryl dichlorides.

Photoresponsive gels exhibit various applications because they can change their structures and properties under the stimulation of light. However, the use of photoresponsive gels is limited by solvent evaporation, which compromises their longevity and functionality. Herein, we design a metallopolymer organogel to overcome this challenge. The organogel incorporates metal–ligand coordination bonds as reversible, photoswitchable crosslinks within a polyacrylamide network, using high-boiling-point 1,2-propanediol as the solvent. This system exhibits excellent stability against solvent loss and displays fully reversible and photoresponsive behaviors, including gel-to-sol transitions, color change and volumetric expansion/contraction. We use these properties to demonstrate rewritable photopatterning and shape reconfiguration. We also demonstrate that the organogel maintains low solvent evaporation and stable performance even under high-temperature conditions. The metallopolymer organogel design opens avenues for the development of long-lasting, intelligent soft matter for use in demanding applications.

Post-polymerization modification (PPM) has become a pivotal strategy in modern polymer chemistry, enabling the late-stage functionalization of pre-formed polymer backbones. Among the many reactive motifs employed, fluorinated units have played a central role due to their exceptional electronic properties and chemical robustness. While perfluorinated motifs have traditionally been utilized in polymer materials and PPMs, the exploration of partially fluorinated units remains limited. In this Mini-Review, we highlight recent advances in PPMs in the context of existing methodologies and emphasize the synthetic utility of fluorine-containing units in PPM design. Particular attention is given to α,α-difluoroacetates, a class of partially fluorinated esters that uniquely combine carbonyl activation with α-position masking. The recent integration of α,α-difluoroacetates has enabled efficient aminolysis-based PPMs and, remarkably, has allowed for the regeneration of activated ester polymers. These findings establish the first example of a regenerable aminolysis PPM, marking a conceptual shift toward dynamic and recyclable polymer modifications.

Poly(ionic liquid)s (PILs), with their inherent ionic functional moieties and tunable macromolecular architectures, exhibit distinct advantages in heterogeneous catalysis, including high charge density, customizable porous frameworks, and abundant active sites. However, to date, no comprehensive review has systematically summarized task-specific PILs for heterogeneous catalytic applications. This review provides a critical overview of three representative synthetic strategies for PIL-based catalysts: (1) one-pot ionomerization to produce functional poly(ionic liquid)s with selected comonomers; (2) post-polymerization functionalization to achieve precise introduction of functional groups for spatial control of active sites; (3) confined-space encapsulation (“ship-in-a-bottle” strategy) to realize restricted growth of active species and enhance catalytic stability. These well-defined PILs can directly serve as task-specific heterogeneous catalysts for esterification, CO₂ cycloaddition, and biomass conversion through synergistic ionic interactions, or be integrated with heteropolyacids, noble metal nanoparticles, metal oxides, and enzymes to construct synergistic/tandem catalytic systems. The review further highlights paramount challenges in achieving precise structural control of PILs, improving recycling stability, and developing multi-component synergistic catalysis platforms, thereby offering novel perspectives for the rational design of advanced heterogeneous catalysts.

In this study, pendant vinyl functionalised polysiloxane oils were converted into dynamic, self healing elastomers after crosslinking with elemental sulfur through vulcanisation. Three polysiloxanes with varying vinyl content, chain length, and functional groups were directly reacted with elemental sulfur (S₈), generating three different crosslinked materials: X-poly(PDMS-PVMS-r-S), X-poly(PVMS-r-S), and X-poly(PPMS-PPVS-r-S), where X is wt% sulfur. The reactions were monitored by solution state ¹H NMR spectroscopy, confirming progressive vinyl consumption by the decrease in vinyl proton signals (δ_H = 5.7–6.2 ppm), and simultaneous appearance of CH/CH₂–S bonds (δ_H = 2.0–3.0 ppm). Vitrification times varied across the three polymers, primarily influenced by the polysiloxane chain length, vinyl content, other pendant functional groups, and sulfur loading, with higher sulfur content generally leading to shorter times. Solid state NMR spectroscopy on the final cured elastomers confirmed vinyl consumption and CH/CH₂–S bond formation, and thermogravimetric analysis (TGA) showed a lower char yield with higher sulfur incorporation, consistent with the increased proportion of thermally labile polysulfide linkages. Glass transition temperatures measured via DSC were higher in the phenyl containing polysiloxane, up to −3 °C, compared to the methyl rich polysiloxanes (T_g < −70 °C) due to the reduced backbone mobility from the bulky phenyl substituents. Contact angle measurements confirmed that all elastomers remained highly hydrophobic (104–111°). Rheological analysis demonstrated increasing tan δ values with sulfur content, attributed to a higher density of dynamic crosslinks. After physically damaging the materials and thermal healing, efficient S–S bond reformation restored mechanical integrity, while minor irreversible changes modestly influenced viscoelasticity. In addition, DMF enabled a solvent-based route to depolymerisation–recrosslinking. 10-Poly(PPMS-PPVS-r-S) dissolved fully in DMF, whereas 10-poly(PVMS-r-S) and 7-poly(PDMS-PVMS-r-S) were only partially soluble. After removing DMF and briefly annealing (140 °C, 1 h) the elastomers were regenerated, providing chemical recyclability alongside thermal healing. These results show that pendant-vinyl polysiloxanes can be directly converted into dynamic, repairable elastomers through catalyst and solvent-free vulcanisation using elemental sulfur, a refinery by-product, as the sole crosslinker. The process is 100% atom economical and generates materials which extend silicone lifetimes while valorising industrial sulfur waste.

Novel mono glyceryl ethers (MGEs) were synthesized from biomass-based sources and used as diol monomers for synthesizing comb-shaped polyesters (comb-shaped polymers (CSPs)). MGEs with varied alkyl chain lengths (m values) were polymerized with biomass-based diacids of varied alkyl chain lengths (n values) via polycondensation, yielding a series of (32 kinds of) MGE-based CSPs with diverse m and n combinations. The resulting CSPs had molecular weights > 10 000 g mol⁻¹ (after purification) with a high reaction extent (≥91%). The melting temperatures (T_m) were systematically studied with respect to (1) the branch alkyl chain length (m), (2) the backbone alkyl chain length (n), (3) the branch position in MGE (Sn-1 or Sn-2 positions), and (4) the difference between ether-linked and ester-linked branch chains. Notably, several CSPs showed particularly low T_m (below 0 °C) or even no T_m (with no crystallinity), which is not attainable by linear polyesters. These CSPs may find unique future applications such as low-temperature lubricants.

We report herein the living polymerization of an amphiphilic, helical aramid diblock copolymer made possible by the utilization of the reagent PHOS3. Two monomers, 2,4-bis((2,5,8,11-tetraoxapentadecan-15-yl)oxy)-5-aminobenzoic acid and 5-amino-2,4-difluorobenzoic acid, were used to build the hydrophilic and hydrophobic blocks, respectively. The diblock copolymer was characterized by NMR and GPC/SEC, and its aggregation behavior was investigated using atomic force microscopy (AFM), (depolarized) dynamic light scattering ((D)DLS), and small-angle X-ray scattering (SAXS). The analysis strongly suggests that the diblock copolymer self-assembles to form elongated, tube-like structures in water.

Metallacycle- and metallacage-based supramolecular polymers, which integrate well-defined coordination complexes with polymer chains, represent an emerging frontier in functional materials. This review summarizes recent progress in their synthesis, structural characterization, and potential applications. We discuss strategies for incorporating metallacycles or metallacages as core motifs, building blocks or crosslinking junctions within polymer architectures, illustrated through representative examples. Advanced analytical techniques that reveal hierarchical organization are highlighted, including scanning tunneling microscopy for single-molecule imaging and small-angle X-ray and neutron scattering for mesoscale morphological analysis. The combination of dynamic reversibility and precise geometric configuration in metallacycles and metallacages, alongside the mechanical robustness and processability of polymers, enables supramolecular polymers to function in stimuli-responsive systems, biomedical materials, molecular separation, and photocatalysis. Remaining challenges and future opportunities are outlined, providing a conceptual blueprint for researchers interested in this rapidly advancing field.

Gated photochemistry provides a powerful strategy for modulating polymer architecture under mild conditions through light-controlled reversible bond formation. Quinolinone-based photoactive units are introduced as a robust and tunable motif for reversible [2π + 2π] photocycloaddition, enabling wavelength-gated photopolymerization and depolymerization. Telechelic macromonomers bearing quinolinone end groups undergo efficient light-triggered polymerization to yield high-molecular-weight polymers (M_p ≈ 60 000 Da), followed by nearly complete depolymerization back to the original macromonomers under distinct irradiation wavelengths—without catalysts or additives. Systematic investigation of oxygen concentration, irradiation wavelength, and monomer concentration revealed a complex interplay governing reaction efficiency and reversibility. Oxygen enables red-shifted operation (up to 45 nm) and modulates the photostationary equilibrium, while concentration determines the balance between intermolecular chain extension and intramolecular cyclization. This wavelength- and environment-tunable photochemical response achieves reversible polymer formation, including under ambient conditions. The demonstrated tunability and reversible behavior establish quinolinone-based photoswitches as a versatile platform for recyclable and reprocessable light-responsive polymer systems.

Block copolymer self-assembly in solution offers a versatile platform for designing nanostructures with tailored morphologies in aqueous environments. While morphology is commonly controlled by adjusting block ratios, kinetic trapping of nanostructures represents a powerful yet underexplored strategy to direct shape and structure formation, for example in biomedical applications. In this study, we investigate the self-assembly behavior of the amphiphilic block copolymer poly[(butyl acrylate)₅₀-co-(pyridyl disulfide ethyl acrylate)₅]-block-(poly ethylene oxide)₁₂₅-N₃ (P(BA₅₀-PDSA₅)-b-PEO₁₂₅-N₃) using a solvent switch method. The polymer features a neutral, biocompatible hydrophilic block and a hydrophobic block with a low glass transition temperature (T_g). By systematically varying the initial solvent composition (DMSO/acetone), polymer concentration (1, 4, 7 mg mL⁻¹), and water addition rate (1, 2, 4, 20 mL h⁻¹), we demonstrate precise control over nanoparticle morphology. DMSO content above 80% favored vesicle formation, while balanced DMSO/acetone mixtures stabilized worm-like micelles. Lower polymer concentration of 1 mg mL⁻¹ resulted in a decrease in the formation of non-spherical morphologies, and faster water addition rate of 4 mL h⁻¹ broadened the worm phase, indicating a strong influence of kinetics on the final morphology. Characterization via asymmetric flow field-flow fractionation (AF4), dynamic light scattering (DLS), and cryogenic transmission electron microscopy (cryo-TEM) revealed sharp transitions and mixed phases, highlighting the sensitivity of the system to subtle assembly conditions. These findings provide mechanistic insights into morphology control and underscore the potential of kinetically guided self-assembly for designing shape-specific nanostructures, which is particularly relevant for biomedical applications where nanoparticle shape influences biodistribution, cellular uptake, and therapeutic efficacy.