Macromolecules最新文献

{"title":"Synthesis of Vanillin-Based Polyurethane with Super Thermal Stability and Free-Radical-Scavenging Activity","authors":"Weijun Yang, Binbao Lu, Debora Puglia, Deyu Niu, Pengwu Xu, Piming Ma","doi":"10.1021/acs.macromol.4c01354","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01354","url":null,"abstract":"This work focuses on designing biobased polyurethane systems possessing intrinsic free radical scavenging activity (RSA), exceptional toughness, and thermal stability. Initially, divanillyl alcohol (DVO) was synthesized through oxidative coupling activation of the vanillin precursor, followed by reduction of aldehyde groups. Subsequently, polyurethanes denoted as RSPU-<i>x</i> (where <i>x</i> is the molar ratio of DVO) were synthesized, using polycaprolactone diol (OH-PCL–OH) as the soft segment and isophorone diisocyanate (IPDI) along with DVO as the hard segments. With an increase in the DVO content from 0 to 0.25, the thermal stability and mechanical properties of RSPU-<i>x</i> were significantly enhanced. Specifically, the maximum thermal decomposition temperature rose from 317 to 417 °C, while the toughness shot up from 38.1 MJ/m³ to 223.9 MJ/m³. The improvement of thermal stability is attributed to the biphenyl structure of DVO, which has high bond dissociation energy and exceptional free radical scavenging activity, while enhanced toughness primarily results from the introduction of the DVO rigid skeleton, which disrupts the regularity of PCL chains, thereby inhibiting PCL crystallization behavior. Additionally, RSPU-<i>x</i> also exhibited inherent free radical scavenging activity due to the presence of Ar–OH groups in the skeletons. The RSA of RSPU-0.25 (DPPH and ABTS tests) reached, respectively, 94.21% and 99.24% within 0.5 h, achieved via the H⁺ transfer mechanism. This work presents a novel strategy for preparing polyurethanes with exceptional thermal stability and RSA properties.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"25 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142902059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Blue Multiresonance Thermally Activated Delayed Fluorescence Conjugated Polymers for Solution-Processable Narrowband Blue Organic Light-Emitting Diodes with High Color-Purity","authors":"Tao Wang, Shuni Wang, Junjie Dong, Guohao Chen, Jiahui Liu, Manli Huang, Zhanxiang Chen, Zhongyan Huang, Chuluo Yang","doi":"10.1021/acs.macromol.4c02674","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02674","url":null,"abstract":"Thermally activated delayed fluorescence (TADF) conjugated polymers generally exhibit red-shifted photoluminescence (PL) spectra compared to their TADF chromophores, owing to the extension of conjugation along the polymeric backbone. Developing blue TADF-conjugated polymers, particularly those with high color purity, continue to pose a significant challenge. Herein, we design and synthesize a batch of blue multiresonance (MR)-TADF-conjugated polymers, by grafting an MR-emitting moiety as a pendant onto a conjugated backbone through the unilateral <i>para</i>-carbon position of the nitrogen atom within the MR moiety. These new polymers exhibit blue emissions with PL emission peaks ranging from 459 to 477 nm, accompanied by full width at half-maximum (FWHM) values between 24 and 27 nm. Their electroluminescent devices via solution-processing demonstrate pure blue emissions with a EQE_max of 10.1%, Commission Internationale de I’Eclairage (CIE) coordinates of (0.14, 0.12) and a FWHM of 31 nm, peaking at 462 nm, which demonstrate the best performance among TADF conjugated polymer-based blue organic light-emitting diodes with CIE_<i>y</i> values of below 0.15.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"65 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Grazing Incidence Wide-Angle X-ray Scattering of Water Adsorption in Polyamide Barrier Layers of Reverse Osmosis Membranes","authors":"Qinyi Fu, Size Zheng, Nisha Verma, Roberto Gambarini, Tao Wei, Benjamin M. Ocko, Benjamin S. Hsiao","doi":"10.1021/acs.macromol.4c02699","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02699","url":null,"abstract":"To understand the relationship between the intermolecular structure of aromatic polyamide (PA) scaffold and the water molecules in the barrier layers of reverse osmosis (RO) membranes, a grazing incidence wide-angle X-ray scattering (GIWAXS) study was carried out on freestanding PA thin films at varying relative humidity (RH) conditions. The scattering results were analyzed by an interference scattering model, containing a phase factor between a PA chain and an adsorbed water molecule. This model yielded good fits to the GIWAXS profiles where the water adsorption was found to vary linearly with RH. Atomistic molecular dynamics (MD) simulations were also performed to complement the experimental study. The simulations revealed that a rapid condensation layer initially formed on the PA film surface, followed by the slow water molecule diffusion inside the PA membrane. Sparse adsorbed water, isolated in subnanopores of the PA film adjacent to the polar atoms, even in very low quantities, modifies the X-ray scattering. Atomistic simulations at the microscopic scale provide partial support for several X-ray scattering findings.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"34 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toward the Relative Stability of Frank–Kasper Phases Formed by Neat Diblock Copolymer Melts and Binary Blends","authors":"Zhiwei Zhuang, Juntong He, Jianguo Tang, Qiang Wang","doi":"10.1021/acs.macromol.4c02119","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02119","url":null,"abstract":"Using the well-developed polymer self-consistent field (SCF) calculations of the “standard” model, we found that the relative stability among seven Frank–Kasper phases (A15, σ, H, Z, pσ, C14, and C15) formed by both neat diblock copolymer (DBC) A-B melts and binary DBC blends is dominated by their internal-energy densities (i.e., the repulsion between A and B blocks). This trend is also found in other SCF data (including those for the binary blends of DBC and a homopolymer) regardless of the detailed models used. We further found that variations of the Helmholtz free-energy and internal-energy curves of different FK phases are clearly correlated with the average coordination number (CN) <i>z̅</i> of the Wigner–Seitz polyhedra (which is equivalent to the average number of 6-fold rotation axes) in these FK phases, and defined the internal-energy-weighted and the Helmholtz-free-energy-weighted average CNs, which can be regarded as constant depending only on the FK phase similar to <i>z̅</i> but are more pertinent to its internal energy and Helmholtz free energy, respectively, than <i>z̅</i>. Finally, the change of the stable phase between σ and C14/C15 in binary DBC blends is mainly due to that in the interchain repulsion.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"11 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142887003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using Drude Oscillators to Capture Ion Solvation in Generic Coarse-Grained Molecular Dynamics Simulations of Polymer Electrolytes","authors":"Mengdi Fan, Lisa M. Hall","doi":"10.1021/acs.macromol.4c02082","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02082","url":null,"abstract":"Generic bead–spring models with Lennard–Jones interactions are commonly used to study uncharged polymeric materials. However, incorporating ions into polymer systems requires additional model features to address their long-ranged Coulomb interactions and their interactions with polarizable polymers. This study integrates the Drude oscillator model into coarse-grained molecular dynamics simulations to capture features of ion solvation in polymers. Specifically, we treat coarse-grained beads as polarizable entities with internal dipoles; each bead contains a Drude core bonded with a stiff spring to an oppositely charged Drude particle that does not leave the Lennard−Jones diameter of the core. We first demonstrate the feasibility of this approach in simulations of neat polymers, exploring dielectric constants ranging from 2 to 12. To manage strong local interactions in high-polarizability systems with ions, we propose combining this approach with implicit strategies such as adjusting the background dielectric constant and scaling down ion charges. By combining these explicit and implicit methods, we can gain control over structural features like ion clustering and peak heights in radial distribution functions, enhancing our ability to model features of ion solvation and dielectric response in polymer systems.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"103 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Engineering Polymer Architecture Through Reaction Rates","authors":"Keelee C. McCleary-Petersen, Kaitlyn R. Wiegand, Michael T. Taleff, Damien Guironnet","doi":"10.1021/acs.macromol.4c01662","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01662","url":null,"abstract":"The properties of macromolecules are intrinsically linked to their chemical composition, molecular weight distribution, and architecture. Variation of these features enables the creation of a vast chemical space capable of accommodating diverse material properties and applications. This review focuses on synthetic methodologies that exploit reaction rates to engineer the architecture of polymers. More specifically, three complementary synthetic strategies were identified: the first strategy is varying the reactivity of the monomers; the second strategy is implementing two simultaneous reactions (orthogonal or competitive); and, the third strategy is implementing reactor engineering principles, where controlling reactor parameters such as monomer concentration, residence time, and flow rate results in different architectures. Finally, this perspective is concluded with a short discussion about the challenges in <i>a posteriori</i> characterizing the architecture of polymers and the benefit of kinetic models to <i>a priori</i> predict the architecture of a polymer.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"2 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitatively Connecting Experimental Time–Temperature–Superposition–Breakdown of Polymers near the Glass Transition to Dynamic Heterogeneity Via the Heterogeneous Rouse Model","authors":"Peijing Yue, David S. Simmons","doi":"10.1021/acs.macromol.4c00751","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c00751","url":null,"abstract":"Polymers near the glass transition temperature <i>T</i>_g often exhibit a breakdown of time–temperature–superposition (TTS), with chain relaxation times and viscosity exhibiting a weaker temperature dependence than segmental relaxation times. The origin of this onset of thermorheological complexity has remained unsettled and a matter of debate. Here we extend the Heterogeneous Rouse Model (HRM), which generalizes the Rouse model to account for dynamic heterogeneity, to make predictions for the relaxation modulus <i>G</i>(<i>t</i>) and complex modulus <i>G</i>*(ω) of unentangled polymers near <i>T</i>_g. The HRM predicts that <i>G</i>(<i>t</i>) and <i>G</i>*(ω) exhibit enhanced effective scaling exponents in the Rouse regime in the presence of dynamic heterogeneity, with a more rapid decay from the glassy plateau emerging as the system becomes more dynamically heterogeneous on cooling. This behavior is predicted to emerge from a strand-length dependence of the moment of the segmental mobility distribution probed by chain dynamics. We show that the HRM predictions are in good accord with experimental complex modulus data for polystyrene, poly(methyl methacrylate), and poly(2-vinylpyridine). The HRM also predicts the onset of distinct temperature dependences among chain scale quantities such as terminal relaxation time and viscosity in our experimental systems, apparently resolving one of the most significant standing objections to a heterogeneity-based origin of TTS-breakdown. The HRM thus provides a generalized theory of the chain-scale linear rheological response of unentangled polymers near <i>T</i>_g, accounting for the origin of TTS-breakdown at a molecular mechanistic level. It also points toward a new strategy of inferring the dynamic heterogeneity of glass-forming polymeric systems from the temperature–evolution of modified scaling in the Rouse regime.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"33 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gradient Ethylene/α-Olefin Copolymer Prepared via In Situ Copolymerization","authors":"Xinyi Li, Jianhua Wang, Quan Chen, Bo Liu","doi":"10.1021/acs.macromol.4c02122","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02122","url":null,"abstract":"Synthesis of gradient copolymers through coordination insertion copolymerization is an unmet goal since the prerequisite is not only the copolymerization being performed in a living manner but also the composition drift being sensitive to the change of comonomer concentration. Herein, these challenging issues to ethylene/1-hexene polymerization were simultaneously solved by carefully tuning the steric of the <i>ortho</i>-substituent of the amine bis(phenolate) moiety within the corresponding titanium complex. The titanium complex <b>1</b> catalyzed ethylene/1-hexene copolymerization to give gradient copolymers <b>P1</b>–<b>P4</b> within a certain range of 1-hexene concentrations through in situ polymerization and block copolymer <b>P5</b> through a sequential feeding strategy. The structure–property relationship between the phase structure and the mechanical property and electric breakdown voltage were elucidated. Compared to <b>P4</b> containing a tiny crystalline phase, the gradient copolymer <b>P3</b> with a large discrete crystalline phase shows a much higher electric breakdown voltage (209.6 kV/mm vs 146.6 kV/mm) and tensile strength (23.6 MPa vs 3.8 MPa). With the accumulation of crystalline phase in <b>P2</b>, the electric breakdown voltage slightly decreases to 199.7 kV/mm, but the tensile strength improves to 34.0 MPa, which are similar to those of block copolymer <b>P5</b> (<i>E</i>_b = 183.7 kV/mm, σ_b = 32.8 MPa) and superior to those of <b>P1</b> (<i>E</i>_b = 160.7 kV/mm, σ_b = 25.9 MPa) with continuous crystalline phase.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142887004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theory of Ion-Mediated Segmental Localization, Activated Structural Relaxation, and the Glass Transition in Polymerized Ionic Liquids","authors":"Ankita Das, Anisur Rahman, Michelle Lehmann, Catalin Gainaru, Alexei Sokolov, Kenneth S. Schweizer","doi":"10.1021/acs.macromol.4c02240","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02240","url":null,"abstract":"We combine polymer integral equation theory for structural correlations with a force-level theory for activated segmental relaxation to construct a microscopic theory for how ions modify the onset of segmental localization, the polymer alpha relaxation time, and glass transition temperature, <i>T</i>_g, in dry polymerized ionic liquids (PolyILs). Our most important findings concerning the behavior of <i>T</i>_g are (i) a weak dependence on anion–cation Coulomb attraction strength due to strong decoupling of ion and segmental dynamics, (ii) strong reduction with increasing mobile ion size due to both plasticization effects and weakening of ion-modified monomer caging, and (iii) increase with backbone rigidity and intrachain dynamic cooperativity. We quantitatively estimate <i>T</i>_g variations as ion size and polymer static and dynamic rigidity are widely varied. The experimental data of 19 PolyILs are organized into a specific pattern consistent with the theoretical predictions with glass transition temperatures varying over a very wide range (∼250 K) as observed experimentally. Based on the theoretical results, suggestions are made concerning the search for high conductivity Li- or Na-based PolyILs based on further lowering of <i>T</i>_g via new polymer synthesis. Calculations of the alpha time as a function of packing fraction reveal the dynamic fragility increases for larger mobile ions, a more flexible backbone, and/or a smaller degree of intrachain dynamic cooperativity, as a consequence of the increasing importance of collective elasticity in determining the activation barrier. An analysis of transient segmental localization and a crossover to activated dynamics reveals similar, but not identical, trends as predicted at the laboratory vitrification timescale.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"41 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142887005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-Diffusion of Star and Linear Polyelectrolytes in Salt-Free and Salt Solutions","authors":"Aliaksei Aliakseyeu, Erica Truong, Yan-Yan Hu, Ryan Sayko, Andrey V. Dobrynin, Svetlana A. Sukhishvili","doi":"10.1021/acs.macromol.4c01374","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01374","url":null,"abstract":"This work explored solution properties of linear and star poly(methacrylic acids) with four, six, and eight arms (<i>L</i>PMAA, 4PMAA, PMAA, and 8PMAA, respectively) of matched molecular weights in a wide range of pH, salt, and polymer concentrations. Experimental measurements of self-diffusion were performed by fluorescence correlation spectroscopy (FCS), and the results were interpreted using the scaling theory of polyelectrolyte solutions. While all PMAAs were pH sensitive and showed an increase in hydrodynamic radius (<i>R</i>_h) with pH in the dilute regime, the <i>R</i>_h of star polymers (measured at basic pH values) was significantly smaller for the star polyacids due to their more compact structure. Fully ionized star PMAAs were also found to be less sensitive to changes in salt concentration and type of the counterion compared to linear PMAA. While <i>R</i>_h of fully ionized linear PMAA decreased in the series Li⁺ &gt; Na⁺ &gt; K⁺ &gt; Cs⁺ in agreement with the Hofmeister series, <i>R</i>_h of star PMAAs was virtually independent of type of the counterion for eight-arm PMAA. However, molecular architecture strongly affected interactions of counterions with PMAAs. In particular, ⁷Li NMR revealed that the spin–lattice relaxation time <i>T</i>₁ of Li⁺ ions in low-salt solutions of eight-arm PMAA was ∼2-fold smaller than that in the solution of linear PMAA, suggesting slower Li⁺-ion dynamics within star polymers. An increase in concentration of monovalent chloride salts, <i>c</i>_s, above that of the PMAA monomer unit concentration (<i>c</i>_m) resulted in shrinking of both linear and star molecules, with the hydrodynamic size <i>R</i>_h scaling as <i>R</i>_h ∝ <i>c</i>_s^{–0.11±0.01}. Self-diffusion of linear and star polyelectrolytes was then studied in a wide range of polyelectrolyte concentrations (10^–3 mol/L &lt; <i>c</i>_m &lt; 0.5 mol/L) in low-salt (&lt;10^–4 mol/L of added salt) and high-salt (1 mol/L) solutions. In both the low-salt and high-salt regimes, diffusion coefficient <i>D</i> was lower for PMAAs with a larger number of arms at a fixed <i>c</i>_m. In addition, in both cases, <i>D</i> plateaued at low polymer concentrations and decreased at higher polymer concentrations. However, while in the high-salt conditions, the concentration dependence of <i>D</i> reflected transitions between the dilute to semidilute solution regimes as expected for neutral chains in good and theta solvents, analysis of the diffusion data in the low-salt conditions using the scaling theory revealed a different origin of the concentration dependence of <i>D</i>. Specifically, in the low-salt solutions, both linear and star PMAAs exhibited unentangled (Rouse-like) dynamics in the entire range of polyelectrolyte concentrations.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"26 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}