ACS Macro Letters最新文献

Poly(lactic acid) (PLA) serves as a promising alternative to nondegradable conventional plastics, owing to its biobased origin, biodegradability, mechanical strength, and optical clarity. However, its inherent brittleness restricts its broader application. Incorporating rubber particles is an effective and practical approach to improving toughness by inducing matrix plastic deformation. Herein, we prepared a series of imidazolium-functionalized poly[oxy(chloromethyl)ethylene] (PDI#) as dual-functional agents that simultaneously enhance the toughness and antibacterial properties of PLA blends. The imidazolium groups promote strong interactions with PLA chains, significantly reducing the particle size within the PLA blends. Consequently, a PLA blend containing 20 wt % PDI51 achieved a toughness of 9.30 MJ m^–3, representing more than a 15-fold increase compared to neat PLA (0.56 MJ m^–3). Furthermore, 20 wt % PDI#-containing blends achieved potent antibacterial activity against E. coli, exceeding 3-log reduction.

Vitrimers are an emerging class of covalent adaptable networks, which can be reprocessed at elevated temperatures while preserving crosslinking density. In these systems, the onset temperature of bond exchange is often dubbed “topology freezing transition temperature (T_v)” and is characterized by a sharp reduction in material viscosity. Here, we provide a universal and external stress-free method to determine T_v in submicrometer (<μm) supported films, by measuring their thickness change as a function of temperature by ellipsometry. This study investigated a range of vitrimer systems, including catalyst-free, externally catalyzed, and internally catalyzed networks, to confirm the general applicability of our approach. We demonstrate the high sensitivity of ellipsometry in detecting changes in the apparent thermal expansion behaviors of vitrimer films, specifically linked to the onset of bond exchange in vitrimers, which is distinguished from most other methods that primarily capture macroscopic thermomechanical behaviors. Our results also suggest that the mechanism by which ellipsometry reveals the T_v in vitrimers is governed by their change in relaxation dynamics, which are fundamentally distinct from the thermodynamically driven glass transition observed in conventional polymers. We believe the ellipsometric method can not only streamline the characterization of T_v in vitrimers but also provide deeper insights into their dynamic exchange mechanisms by distinguishing between their microscopic and macroscopic properties.

This study investigates the elastic and dynamic properties of elastomeric, stoichiometric epoxy networks formed between the telechelic functionalized poly(ethylene glycol) diglycidyl ether (PEGDE) and the linear cross-linker 1,4-diaminobutane across a range of extensional strain rates (10⁷ to 10¹⁰ s^–1), molar masses (n = 3, 5, 8 repeat units), and two reaction extents determining degree of cross-linking through atomistic simulations and compares them with the experimental n = 8 system. Investigated properties are Young’s and shear moduli, the C₁₁ elastic constant, the glass transition temperature, and the network’s mean-squared-displacement. Results reveal a notable agreement between simulation-obtained and experimental values of C₁₁ and its experimentally determined Brillouin light scattering (BLS) value and glass transition temperatures, bridging the gap between atomistic and macroscopic length scales. This work contributes to the renewed interest of BLS applied on soft systems and lays the groundwork for computational investigations of complex epoxy architectures, such as dual networks with epoxy covalent and noncovalent bonds.

We report the design and self-assembly of amphiphilic imidazolium-based gemini zwitterions with fluorinated anions (ImGZI-TFSI) that form stable gyroid phases via liquid-crystalline (LC) organization under additive-free conditions. By tuning their surfactant chain length and introducing cross-linkable diene groups, we achieved precise morphological control and fabricated free-standing polymer membranes using Diene-C₁₆ImGZI-TFSI. In contrast, the incorporation of diene groups into an analogue with shorter surfactant chains of C14 disrupted gyroid order, which was subsequently restored by lithium chloride (LiCl) addition. These findings highlight the critical role of intermolecular interactions and molecular packing efficiency in LC self-assembly, enabling the design strategy of additive-free, cross-linkable zwitterionic gyroid polymer membranes with potential applications in functional nanostructured materials.

Acrylamide–2-acrylamido-2-methylpropanesulfonate (AM–AMPS) copolymers are important water-soluble polymers widely used across diverse industries. The molecular weight plays a crucial role in determining the characteristics of their aqueous solutions, thereby directly affecting their performances in applications. However, the rapid and accurate determination of their molecular weight has long been a critical challenge for industry. In this work, by systematically measuring the intrinsic viscosities ([η]) and weight-average molecular weights (M_w) (calibrated by static light scattering) of AM–AMPS copolymers with 50 mol % AMPS in 0.5 M NaCl solution, a universal Mark–Houwink equation was established for the first time: [η] = 0.0104 × M_w^0.74 mL/g (R² > 0.99). This equation was validated across at least the M_w range of (0.82–16.1) × 10⁶ g/mol and shown to be applicable to (co)polymers with AMPS contents from 0 to 100 mol %. This work offers a rapid, reliable tool for M_w determination, effectively addressing a longstanding challenge in the production and quality control of AM–AMPS copolymers.

A highly efficient siRNA vector (PFS-CA) capable of selectively silencing genes in cancer cells was obtained by modifying common low-molecular-weight (LMW) polyethylenimine (PEI) with a bioreducible targeted multifunctional module (FS) to get PFS, followed by noncovalently incorporating chlorogenic acid (CA). FS combined folate receptor-mediated targeting for cancer cells with glutathione (GSH)-responsive siRNA release into the cytoplasm. CA, a highly biocompatible natural polyphenol served as a siRNA condensation enhancer, siRNA stabilizer, and ROS scavenger. Consequently, by the synergistic effects between PFS and CA, PFS-CA performs very well on several crucial siRNA delivery processes, including siRNA condensation, complex stability, cell uptake, endosome escape, and siRNA cytoplasmic release. The representative PFS4-3CA exhibited superior transfection efficiency in a variety of cancer cell lines, including neurogenic tumor-related PC12 cells, than commercial PEI_25k and Lipo_2k, and extremely high and selective gene silencing effects in cancer cells (with a gene silencing rate of 98.6% in HepG2 while only 8.4% in HK-2). Our findings demonstrated great promise for the development of a safe and effective siRNA carrier for future applications in tumor-targeted siRNA therapy.

When designing a consumer device, recyclability is not usually a primary consideration. Thus, packaging and encapsulation of interior and exterior components is achieved using robust materials─e.g., metals, glasses, ceramics, and adhesives bearing irreversible cross-links. If recycling is attempted, the high value components are most often liberated by incineration or destructive mechanical processing. Controlled debonding using a reversible adhesive is an approach to circumvent some of this destruction. This paper describes a reversibly cross-linked interlayer polymer (“ReCLIP”) that cures by way of a thermally reversible Diels–Alder (DA) reaction between furan-functionalized silicone chains and an aromatic bismaleimide. Two-dimensional ¹H–¹H COSY NMR experiments were used to distinguish between the exo and endo diastereomers of the furan–maleimide DA adduct. The exo–endo ratio exerted a pronounced influence on the thermal stability and adhesion strength of the resulting polymer network. With one-dimensional ¹H NMR monitoring, we established that the Diels–Alder cross-linking proceeded most rapidly at 80 °C, while complete conversion and a high proportion of the exo adduct (∼93%) were also observed at 60 °C with extended reaction times. One-dimensional ¹H NMR also revealed that the onset of the reverse (retro-Diels–Alder) reaction occurred at ∼90 °C. Using a lap-shear geometry, ReCLIP exhibited a maximum shear strength of 286 ± 50 kPa, comparable in magnitude to values seen for other silicone adhesives. Films exhibited excellent transparency and stability over time under ambient conditions.

Low molecular weight α,ω-dicarboxylic acid triblock polymers, featuring polycarbonate blocks flanking a central polyester block, are synthesized and assembled into dynamic halatopolymers via Zn(II) coordination. The number of chains coupled through Zn(II)–carboxylate interactions is tuned by using 4-tert-butylbenzoic acid (tBBA) as a sterically hindered capping ligand. Reducing tBBA content vs polymer and zinc content increases the number of junctions connected and the effective halatopolymer molar mass, leading to polymers with higher zero-shear viscosities, slower relaxation dynamics, and more pronounced elastic behavior. Temperature ramp, time–temperature superposition, and creep recovery experiments confirm enhanced dimensional stability and reduced flow under load as the degree of chain coupling increases. In the absence of Zn(II), the polymers display purely viscous behavior, highlighting the critical role of reversible metal–ligand interactions in network formation. This strategy provides a modular route to convert synthetically accessible, renewably sourced, low molar mass polymers into tunable, functional materials, offering a design platform for a new generation of polymeric materials.

Iodine has long been recognized as a chain transfer agent in radical polymerizations, enabling controlled synthesis through reversible C–I bond exchange. Recent advancements have expanded its role as a nonmetallic Lewis acid, driven by halogen bonding and three-center-four-electron (3c4e) interactions. This Viewpoint examines the evolution of iodine-mediated radical polymerization and highlights the role of 3c4e interactions in supramolecular chemistry and polymer synthesis, with a particular focus on ring-opening polymerizations (ROP) and CO₂-based copolymerizations. These developments bridge radical chemistry with halogen bonding, offering environmentally friendly, metal-free alternatives to traditional methods. We explore how iodine catalysis contributes to sustainable polymer synthesis and propose strategies for advancing high-performance, sustainable polymerization systems.

In this work, an electrochemical platform based on poly(3,4-ethylenedioxythiophene) doped with sulfonated β-cyclodextrin (PEDOT:SBCD) was developed for the simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA), l-tyrosine (l-Tyr), and nitrite (NO₂^–). The PEDOT:SBCD composite was synthesized via oxidative polymerization and characterized in detail. Afterward, under optimal conditions, the linear ranges were 5–4000 μM for AA, 0.1–250 μM for DA, 0.1–250 μM for UA, 5–1500 μM for l-Tyr, and 5–1000 μM for NO₂^–, and the detection limits were 1.581 μM (AA), 0.061 μM (DA), 0.122 μM (UA), 0.629 μM (l-Tyr), and 0.510 μM (NO₂^–), respectively. Notably, the platform achieved direct detection in real urine samples with minimal pretreatment, demonstrating excellent anti-interference capability and long-term stability. Additionally, it consistently detected target analytes in actual urine samples from volunteers of varying genders and age. This work provides a potential robust electrochemical platform for personalized and preventive healthcare.