ACS polymers Au最新文献

Primary amines are of utmost importance for the design of various polymeric materials, because of their reactivity, low cost and widespread availability. This is demonstrated by the numerous cross-linking strategies of thermosets that rely on the reaction of multifunctional amines with for example epoxides, esters or aldehydes. Tris-(2-aminoethyl)-amine (TREN) has long remained the only large-scale available, low mass trifunctional primary amine. Despite its known toxicity, significant vapor pressure and several drawbacks related to its tertiary amine functionality, including oxidation-induced coloration, reduced thermal stability and increased reactivity, TREN helped to shape the field of covalent adaptable networks (CANs). On the other hand, we anticipated that triaminononane (TAN) as an alternative low-viscosity trifunctional primary amine would not face the same difficulties because of its fully aliphatic structure. Therefore, in this study we compare the performance of TREN and TAN by synthesizing CANs using two well-established dynamic chemistries, i.e. amide-imide and vinylogous urethane exchange. Through an in-depth study of their thermomechanical properties, the influence of both cross-linkers was examined, providing valuable insights for researchers in selecting the most suitable cross-linker.

In this study, we report degradable acrylic polymers obtained by main-chain scission (MCS) via intramolecular transesterification and their application as UV-curable adhesives that allow for gentle dismounting. The solution polymerization of ethyl α-(hydroxymethyl)-acrylate (1) and cyclic allyl sulfide 2 afforded copolymers with ester bonds in their main chains, which underwent MCS in the presence of 1,5,7-triazabicyclo[4.4.0]-dec-5-ene (TBD). Similar bulk polymerization afforded cross-linked copolymers swollen in N,N-dimethylformamide (DMF), which were decomposed into soluble oligomers via MCS by TBD. Two glass plates were adhered by the bulk photopolymerization of 1 (90 mol %) and 2 (10 mol %) with strengths higher than 9.0 MPa. Soaking these plates in a 10 mM TBD/DMF solution at 25 °C drastically reduced their adhesion strength, and the plates easily peeled off. The adhesion areas decreased over time owing to dissolution by MCS. Thus, MCS using an intramolecular reaction was effective in achieving fast and selective dismounting under ambient conditions.

Nonlinear shear response of polymers is affected by inherent barriers for diffusive motion, including entanglements and topology. In ionizable polymers, ionic clusters further constrain the intrinsic dynamics of the polymers, significantly enhancing their viscosity. Here, using fully atomistic molecular dynamics simulations, the nonlinear shear response of ionizable polymers is presented, across the transition from the ionomer regime where distinctive clusters dominate the structure to the polyelectrolyte regime where clusters percolate, in polystyrene randomly sulfonated with fractions of SO₃ ^- groups of f = 0.20 and 0.35, in pristine and tetrahydrofuran (THF) swollen polyelectrolyte melts. For f = 0.20, the ionic clusters first fracture into smaller clusters followed by splitting into individual ionic groups and eventually reform. At higher f, the clusters morph in shape but do not break under high shear. At very high shear rates, all of the chains stretch and recoil rapidly. As the shear rate is reduced, some chains stretch and recoil, while others remain largely unaffected by the shear. Macroscopically, for all systems, the shear viscosity displays initially an elastic response, followed by nonlinear shear stress overshoot and, eventually, a steady state. The evolution of viscosity with time and shear reflects that of the ionizable domains.

This study leverages machine learning (ML) to accelerate the development of antifungal synthetic polymers. An in-house curated data set was used to train a Random Forest binary classification model, which identified five critical features for predicting antifungal activity against the fungal pathogen Candida albicans. This model shows that antifungal polymers should contain a hydrophilic composition of at least 30%, a calculated partition coefficient (cLogP) of 0 to +0.5, hydrophobic composition limited to 20%, degree of polymerization (DP) of 18 or less, and cationic composition limited to 50% for the polymer to have an MIC₉₀ of 64 μg/mL or less. Based on these insights, a library of polymers was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using 2-(butylthiocarbonothioylthio)-propanoic acid (BTPA) as the RAFT agent, exploring combinations of these features. A polymer exhibiting all five feature characteristics for an effective antifungal polymer presented an MIC₉₀ of 32 μg/mLlower than the 64 μg/mL Class 1 "good" polymer threshold. After optimizing the polymer for significant antifungal activity by fulfilling the five features of the antifungal impact, we improved its biocompatibility. We did this by replacing the BTPA RAFT agent with 2-dodecyl thiocarbonothioylthio-propanoic acid (DTPA), which has a longer, more hydrophobic end-group. This modification resulted in a polymer with an MIC90 of 16 μg/mL and a hemolysis concentration (HC50 exceeding 2000 μg/mL, yielding a selectivity index greater than 125aligning with the most competent polymer involved in the ML data set. This work validates the efficiency of ML-guided design for developing advanced antifungal polymers with enhanced potency and biocompatibility.

A computational phantom Force Balance, Maximum Entropy Homogenization Procedure is presented to predict the equilibrium shear modulus of entangled polymer networks. A Monte Carlo method is used to generate periodic bead-spring microstructures of polymer networks. Entanglements are introduced by merging two internal beads of adjacent network strands, yielding additional tetrafunctional cross-links. The microstructures are optimized to their minimum free energy state, for which the modulus is readily available. The procedure is validated by comparing its modulus predictions with those from both stress-relaxation molecular dynamics (MD) simulations and the Miller-Macosko theory (MMT). Near-perfect agreement with both the MD and MMT results is obtained, with the required computational resources being about four and more orders of magnitude smaller than those in the MD simulations. Finally, good agreement with experimental results over a variety of different polymer networks is demonstrated, including those with bottlebrush and comb-like polymer strands and also near-critical gels, suggesting that the presented procedure can be practically used to predict the modulus of arbitrary polymer networks.

The importance of early detection of neurodegenerative disorder biomarkers has grown since these biomarkers are essential for timely diagnosis, treatment, healthcare, and wellness applications. We present a cost-effective and disposable electrochemical immunosensing strip for rapid, decentralized detection of brain-derived neurotrophic factor (BDNF)─one of the major neurotrophins (NTs) associated with neurological and psychiatric disorders─in human saliva. The salivary BDNF immunosensor strip is made on a screen-printed carbon electrode functionalized with carbon spherical shells (CSSs), polyethylenimine (PEI), and glutaraldehyde to enhance sensitivity. Through systematic optimization, the sensor achieved excellent analytical performance, with a wide dynamic detection range from 1.0 × 10^–20 to 1.0 × 10^–10 g mL^–1, a rapid response time of under 3 min, and an ultralow detection limit of 1.0 × 10^–20 g mL^–1 for BDNF in human saliva. The BDNF immunosensor demonstrated high selectivity, reproducibility, robustness, stability, and long-term storage capability. At a cost of less than US$ 2.19 per unit, this disposable sensor also enabled rapid BDNF detection in saliva samples collected from healthy volunteers without interference from other salivary constituents. The environmental impact was assessed using the Analytical Eco-Scale (AES), the Analytical GREEnness Metric Approach (AGREE), and the Blue Applicability Grade Index (BAGI), which evaluates the practicality (“blueness”) of the device. These assessments confirmed the sustainability of the disposable BDNF immunosensor strip. This device provides a rapid, efficient, cost-effective, and reliable method for the decentralized, noninvasive salivary analysis of BDNF, enabling broader applications in healthcare, wellness monitoring, and medical diagnostics related to the neurotrophin family of biomarkers.

Additive manufacturing utilizes various reactive precursors to fabricate diverse products, including prototypes, functional components, and designer objects. This work presents a synthesis approach toward a novel biobased printable compound, 2-hydroxypropyl ricinoleate dimethacrylate (2-HPRDM). Our proposed strategy involves the castor oil transesterification process, producing 2-hydroxypropyl ricinoleate (2-HPR). We used high-performance liquid chromatography (HPLC) analysis to investigate the reaction progress at equimolar and excess reactant concentrations. This fatty acid ester was modified with methacrylic anhydride to form 2-HPRDM, releasing the secondary reaction product methacrylic acid (MA). This compound was used for the synthesis of propylene glycol dimethacrylate (PGDMA), which valorized all potential wastes generated during the 2-HPRDM production. This article presents the innovative vacuum-distillation esterification approach that generates PGDMA. All synthesized compounds were structurally characterized via NMR, ESI-MS, and FTIR analyses. The formed curable compounds were fabricated into testing specimens and a detailed prototype by an mSLA three-dimensional (3D) printer to confirm their usability. The 3D-printed object was used for the mechanical and thermomechanical characterization of the formulated curable resins via dynamic mechanical analysis (DMA), tensile, and flexural tests. The best-performing 2-HPRDM-based system contained 45 wt % of PGDMA and recorded a storage modulus of 750 MPa, a glass-transition temperature of 85.6 °C, a cross-linking density of 18.9 kmol/m³, a tensile strength of 16.1 ± 2.4 MPa, and a flexural strength of 14.3 ± 1.0 MPa.

Polymeric nanomaterials have emerged as promising carriers for drug delivery systems, offering improved therapeutic efficacy and reduced toxicity. In this study, we present an environmentally friendly and scalable approach for engineering nanogels as an innovative delivery platform for Amphotericin B (AmB), which is a potent antifungal agent. The nanogel system, named NanoT, was synthesized via an amine–epoxide reaction, enabling effective encapsulation and sustained release of AmB. Comprehensive physicochemical characterization was conducted using transmission electron microscopy (TEM), dynamic light scattering (DLS), ζ potential analysis, proton nuclear magnetic resonance (1H-NMR), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and synchrotron-based ultra-small angle X-ray scattering (USAXS). These analyses confirmed the successful formation of spherical nanogels and provided insights into their structural features. Additionally, molecular simulations indicated noncovalent interactions between AmB and the nanogel particles, supporting polymer-drug interactions. The NanoT system achieved an AmB loading capacity of approximately 55%. Notably, encapsulation promoted the formation of AmB superaggregates, which facilitated a controlled release of the active drug, leading to a 4-fold enhancement in antifungal activity. Mechanistic studies suggest that the antifungal efficacy of NanoT is attributed to both the sustained release of AmB and the electrostatic interactions with fungal cell surfaces. Overall, this study demonstrates the potential of amine–epoxide-based nanogels as effective carriers for antifungal therapeutics and contributes significantly to the development of advanced polymer-based drug delivery systems.

The synthesis of well-defined and multifunctional polymeric systems for drug delivery is a topic of intense research. However, a major limitation in the functionalization of these systems for nanomedical applications is the reliance on toxic catalysts or non-biocompatible strategies for polymer coupling and ligation, as well as the need for extensive purification steps when multiple functionalization reactions are performed. In this work, we introduce tetrazines containing both a methyl sulfide and hydroxyl functionality as the initiator for ring opening polymerization of l-lactide. We demonstrate that the obtained polymer can be successfully conjugated to mPEG-SH by chemoselective tetrazine-thiol exchange in a traceless manner. The byproduct, methanethiol, is easily eliminated during the course of the reaction, thus avoiding the use of a toxic catalyst. Additionally, the same end group allows for further functionalization via inverse electron demand Diels-Alder chemistry using trans-cyclooctene. These findings highlight the potential of TeTEx to access complex polymeric systems for biomedical applications by enabling two distinct postpolymerization functionalizations at a single end group, notably in a truly traceless manner.

The exclusive synthesis of a series of end-functionalized conjugated polymers, poly-(9,9'-di-n-octylfluorene-2,7-vinylene)-s (EF-PFVs) containing different end groups (chromophores), enabled by adopting acyclic diene metathesis (ADMET) polymerization using a molybdenum catalyst, Mo-(CHCMe₂Ph)-(N-2,6-Me₂C₆H₃)-[OC-(CH₃)-(CF₃)₂], followed by termination, treating with various aldehydes through Wittig-type cleavage, has been demonstrated. The formation of the EF-PFVs containing different end groups was further confirmed by the analysis of their photophysical properties through steady-state and time-resolved fluorescence studies for PFVs containing one or two terthiophene units. These EF-PFVs exhibit multicolored emissions. The EF-PFVs containing coumarin and F-BODIPY as end groups, expressed as Coumarin-PFV-F-BODIPY, showed white light emission with high efficiency (Φ_PL = 71-75%). The emission properties (CIE coordinates and fluorescence spectra) of the EF-PFVs containing chromophores were strongly affected by the end groups and the PFV chain lengths employed.