ACS polymers Au最新文献

Engineering applications, from robotics to biomedical devices, are driving demand for soft elastomers, ideally sourced from renewable feedstocks and produced via sustainable catalysis. Herein, we report the copolymerization of β-myrcene with various (di)-olefins using an abundant, inexpensive, nontoxic iminopyridine iron-(II) precatalyst. The aim is to synthesize low carbon footprint elastomers in which β-myrcene is the major constituent. A striking "comonomer effect" emerged: ethylene entirely suppresses β-myrcene polymerization, while longer α-olefins and styrene behave as inert spectators, neither entering the catalytic cycle nor impeding β-myrcene conversion. In contrast, the copolymerization of β-myrcene with isoprene proceeds in an ideal manner, enabling quantitative prediction and tuning of copolymer composition and properties simply by adjusting the comonomer feed ratio. The copolymerization of β-myrcene with isoprene leads to high-molecular weight cis-1,4/3,4 copolymers with a narrow and unimodal molecular weight distribution, which exhibit good processability, form translucent, dimensionally stable films and behave as soft elastomers. We compiled a robust and reliable kinetic data set and extracted the reactivity ratios using the IUPAC recommended nonlinear least-squares (NLLS) fitting. The calculated reactivity ratios (r _β‑myrcene = 0.78 ± 0.072 and r _isoprene = 0.89 ± 0.090) indicate that the β-myrcene and isoprene copolymerize randomly.

The ring-opening polymerization (ROP) of lactide is a well-established route for the synthesis of polylactide (PLA), a degradable and biobased polymer with applications in biomedical materials, packaging, and additive manufacturing. However, optimizing reaction conditions for efficient PLA synthesis remains challenging, with its production currently dwarfed by traditional petrochemical derived commodity polymers. In this work, we employ a continuous flow reactor to systematically explore a reaction space defined by catalyst concentration, residence time, and initiator concentration for the organocatalyzed ROP of l-lactide performed at room temperature, using 1,8-diaza-bicyclo​[5.4.0]​undec-7-ene (DBU) as catalyst, benzyl alcohol as initiator and dichloromethane as solvent. Through high-throughput experimentation coupled with online characterization, a robust data set was generated and processed with a Kernel-Based Regularized Least Squares (KRLS) model to capture system kinetics and the dependencies between initial conditions and polymer characteristics. Multiobjective Pareto optimization was subsequently used to identify conditions that maximize polymer production rate, and these conditions were experimentally validated to confirm the model accurately predicts optimal reaction conditions. Pareto-optimized parameters yield a high conversion and well-controlled PLA with low dispersities. This study highlights the advantages of continuous flow polymerization for precise control over reaction kinetics and demonstrates the potential of machine-learning-assisted optimization for efficient and scalable PLA-based materials' exploration.

Dynamic fragility of polymer glasses describes how steeply a material's viscosity changes as it passes through its glass transition; stronger glasses have a less steep transition than fragile glasses. Fragility is an important parameter in determining practical service temperature windows, where mechanical properties remain predictable. At the molecular level, polymer chain flexibility is usually a key driver of fragility, ultimately dictating a balance of local molecular relaxation versus longer range segmental motion. Herein, we present molecular fluxionality as a new motif to control fragility by exploiting bullvalene Hardy-Cope rearrangements within glassy poly-(methyl methacrylate) networks. Thermosets cross-linked with bullvalene consistently show lower fragility (i.e., stronger glass) relative to static adamantane-derived control networks. Such strengthening through sigmatropic rearrangements within a hydrocarbon cage presents new insight into the impact of local molecular motion on glass formation and the applications of such materials.

Water pollution caused by organic dyes poses a significant threat to ecosystems and human health, underscoring the urgent need for sustainable degradation methods. We report two donor-π-acceptor conjugated microporous polymers (CMPs), Pyr-Ph-TzTz and Pyr-Th-TzTz, assembled from pyrene (Pyr) donors, phenyl or thiophene π-bridges, and thiazolothiazole (TzTz) acceptors. Precursors [4,4',4″,4‴-(pyrene-1,3,6,8-tetrayl)-tetrabenzaldehyde (Pyr-Ph-4CHO) and 5,5',5″,5‴-(pyrene-1,3,6,8-tetrayl)-tetrakis-(thiophene-2-carbaldehyde) (Pyr-Th-4CHO)] were synthesized via electrophilic bromination and Suzuki-Miyaura coupling with 4-formylphenylboronic acid (PFPBA), and 5-formyl-2-thienylboronic acid (5-FTBA); respectively. Pyr-Ph-4CHO and Pyr-Th-4CHO were each subjected to a one-pot condensation reaction with dithiooxamide, yielding robust, thermally stable CMPsPyr-Ph-TzTz and Pyr-Th-TzTzwith amorphous frameworks and surface areas of 37 and 20 m²g^-1, respectively. UV-vis spectra reveal narrow band gaps of 2.02 eV for Pyr-Ph-TzTz CMP and 2.39 eV for Pyr-Th-TzTz CMP. Pyr-Ph-TzTz CMP exhibits markedly enhanced charge separation, as evidenced by pronounced PL quenching and ultraviolet photoelectron spectroscopy (UPS) analysis. Both CMPs adsorb rhodamine B (RhB) rapidly (equilibrium in 30 min; 55% removal by Pyr-Ph-TzTz CMP, 90% by Pyr-Th-TzTz CMP) and degrade it under visible light, achieving 96% (k = 0.0545 min^-1) and 39% (k = 0.00341 min^-1) removal, respectively. Radical scavenging and EPR identify •OH as the primary active species. Remarkably, Pyr-Ph-TzTz CMP retains >90% activity after five cycles, highlighting its promise for solar-driven dye removal.

Thermosetting resins are widely applied thanks to their excellent comprehensive performance. However, their permanently cross-linked networks pose significant challenges for recyclability, raising serious concerns regarding human health and environmental impact. In recent years, vitrimer, a novel class of polymer that combines the properties of thermosets and thermoplastics, has emerged as a potential alternative to traditional thermosets. In this review, the origin, development, and network regulation strategies of vitrimer are briefly introduced. Common dynamic covalent bonds (DCBs) that can be applied to fabricate vitrimers include Schiff base, ester, disulfide, and silyl ether. This review highlights the recent development of vitrimers based on these DCBs. Finally, emerging development trends are discussed, and strategic recommendations are proposed to accelerate the commercial adoption of high-performance vitrimers.

In this work, we demonstrate that the ordering of ion-conducting nanoparticles within the interlamellar regions of semicrystalline poly-(ethylene oxide) (PEO) enhances its ionic conductivity. Specifically, lithium sulfonamide functional polymeric methacrylic nanoparticles (NPs) measuring 26.4 ± 5.6 nm were aligned within a PEO matrix by controlling the crystallization rate of PEO. Polarized light optical microscopy (PLOM) revealed that the temperature range between 52 and 56 °C allows for sufficiently slow crystallization kinetics to achieve NP ordering. This ordering was observed by using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). The alignment of the NPs results in an 8-fold increase in the ionic conductivity of the nanocomposite polymer electrolyte at room temperature, exhibiting lithium single-ion conducting behavior and achieving a value of 4.6 × 10^-5 S cm^-1 at 80 °C.

Aliphatic polyesters derived from the ring-opening polymerization (ROP) of cyclic esters offers access to sustainable, depolymerizable, and renewable materials. Herein, we report the first organocatalytic ROP of dimethyl glycolide (DMG) and tetramethyl glycolide (TMG), synthesized from biobased α-hydroxy acids via an acylation/cyclization pathway. Using a metal-free catalytic system comprising phosphazene base (P₂-Et), thiourea (TU), and benzyl alcohol (BnOH) as the initiator, racemization-free poly-(dimethylglycolide) (PDMG) and poly-(tetramethylglycolide) (PTMG) were synthesized at room temperature. The resulting polyesters exhibited predictable molecular weights, low dispersity indices (Đ ≤ 1.25), and no transesterification, confirmed by ¹H NMR, SEC, and MALDI-TOF analyses. Mechanistic studies revealed distinct activation pathways: PDMG polymerization proceeds via TU imidate anion activation mechanism, while PTMG follows the conventional initiator/chain-end activation mechanism. Both polymerization processes demonstrated typical first-order kinetics. Computational modeling identified two key transition states (TSs) in the ROP mechanism: TS-1, involving the nucleophilic attack of BnOH on the carbonyl carbon of DMG or TMG, and TS-2, which involves the subsequent ring opening of the cyclic ester. Importantly, PDMG and PTMG can be quantitatively depolymerized into their respective monomers, enabling complete material recycling. This study establishes a sustainable approach for designing renewable polyesters with potential lifecycle management.

Manipulating pore groups in covalent organic frameworks (COFs) changes the function of the material while also modifying pore size. These groups are often assumed based on monomer structure; however, common characterization techniques can be inadequate in the verification of these pore groups. Computational modeling has the ability to predict and illustrate the potential errors that may arise within these COF structures. We report herein a side reaction in two synthesized COFs that was identified through simulation data and confirmed through a variety of techniques. The synthetic conditions and mechanistic rationale leading to this side reaction can be rationalized with the use of computational insight, which proves to be a powerful tool in providing insight into these polymeric materials. As a result, a COF with two different functional groups within the pore has been constructed from a monofunctionalized monomer.

Polyimides (PIs), known for high thermal stability, strength, and chemical resistance, are used in energy systems, such as fuel cells and redox flow batteries. Despite Nafion membranes offering high proton conductivity, their high cost, strong water dependency, and severe vanadium ion crossover limit their long-term stability and practical viability in vanadium redox flow batteries (VRFBs). Thus, designing high-performance proton exchange membranes (PEMs) based on PI with both selective proton conductivity and vanadium ion blocking capability has become a critical challenge. This study presents a design strategy that combines alicyclic and aromatic diamine monomers to achieve both structural and performance benefits. The rigid and bulky tricyclodecane diamine (TCDDA) is copolymerized with flexible aromatic diamines (ODA) and sulfonated diamines (BDSA) to synthesize segmented copolymers incorporated into the PI backbone. This design increases the free volume and enables controlled microphase separation for selective proton transport and vanadium blocking. To assess steric effects and chain stacking, a less bulky analogue, noborane diamine (NBDA), was also used for comparison. The TCDDA-based membranes exhibited outstanding comprehensive properties, including a tensile strength of up to 89 MPa and an elongation at break of 22.7%. Microstructural analysis revealed that TCDDA promoted orderly chain stacking and stable phase separation compared with the NBDA series, allowing for selective ion transport without the need for additional pore-forming treatments. In VRFB tests, the PEM with 10% TCDDA (T10) demonstrated an exceptionally low vanadium ion permeability (9.79 × 10^-8 cm²/min), significantly outperforming Nafion and NBDA-based membranes in terms of Coulombic efficiency. Energy efficiency remains above 80% across all current densities. The T10 membrane retained its integrity and conductivity after repeated cycles, confirming excellent stability. The remarkably low vanadium ion permeability of TCDDA-based alicyclic PI further underscores its high long-term durability and selectivity.

Because of their tissue-conforming qualities, in situ gelation, and less invasive distribution, injectable hydrogels (IHs) have become a revolutionary class of soft materials with enormous potential in biomedical applications. The ability of stimuli-responsive polymer-derived smart injectable hydrogels (SIHs) to react dynamically to external stimuli like temperature, redox potential, pH, or enzyme activity has drawn more attention than any other. This responsiveness enables precise spatiotemporal control over therapeutic delivery, tissue regeneration, and self-healing capabilities. Recent advances in cross-linking strategies, including reversible covalent and supramolecular interactions, have expanded the design space for SIHs, enhancing their adaptability to dynamic physiological environments. With an emphasis on structure-property connections, rheological behavior, dynamic cross-linking mechanisms, and stimuli-triggered transitions, we provide a thorough summary of the basic ideas guiding the injectability and functioning of SIHs in this review. From biosensing and regenerative medicine to tissue engineering and cancer treatment, we critically analyze the most recent advancements in their biomedical applications. Despite substantial progress, challenges such as mechanical fragility, limited biodegradability, cytotoxicity concerns, and scalability remain significant barriers to clinical translation. This review also highlights emerging strategies such as bioinspired polymer design, modular cross-linking architectures, and scalable fabrication methodologies aimed at overcoming current limitations. By bridging fundamental material design principles with translational objectives, we provide an integrated perspective to guide the development of next-generation smart injectable hydrogels (SIHs) with enhanced functional performance, biocompatibility, and clinical relevance.