Macromolecules最新文献

{"title":"Designing Highly Entangled, Homogeneous, and Low-Defect Networks for High-Performance Rubbers","authors":"Lingmin Kong,&nbsp;Junqi Zhang,&nbsp;Shaoqi Huang,&nbsp;Rongchun Zhang,&nbsp;Jiaming Li,&nbsp;Zhengtian Xie* and Jinrong Wu*,&nbsp;","doi":"10.1021/acs.macromol.4c0313310.1021/acs.macromol.4c03133","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03133https://doi.org/10.1021/acs.macromol.4c03133","url":null,"abstract":"<p >Rubbers are critical in a wide range of engineering applications; however, conventional processing methods often disrupt the entanglements and introduce defects that compromise their mechanical performance. In this study, we introduce a nondestructive, latex-based processing method for the fabrication of high-performance rubbers with highly entangled, homogeneous, and low-defect networks. As a proof of concept, natural rubber (NR) materials prepared using this novel approach retain their intrinsic entanglements while exhibiting a more homogeneous network structure with fewer defects. This optimized NR network enhances strain-induced crystallization (SIC), achieving a crystallinity of up to 38% and larger crystal sizes. These improvements lead to superior mechanical properties, including a tensile strength of 37.3 MPa, a toughness of 77.3 MJ/m³, a modulus of 2.37 MPa, and a fatigue threshold of 258 J/m², outperforming conventional NR materials. Furthermore, this method is versatile and can be applied to other rubbers, demonstrating its broad potential for producing high-performance rubber materials.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 6","pages":"3109–3118 3109–3118"},"PeriodicalIF":5.1,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678648","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":"Synthesis, Voltammetry, and Spectroelectrochemical Characterization of Tunable Ferrocene-Jeffamine Redox-Active (Co)polymers: Controlling Redox and Ionic Interactions Through Composition","authors":"Nafisa A. Ibrahim, Jeanne N’Diaye, Adolfo I. B. Romo, Raghuram Gaddam, Steven C. Zimmerman, Joaquín Rodríguez-López","doi":"10.1021/acs.macromol.4c02501","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02501","url":null,"abstract":"There is a critical need for predictably modulating the reactivity of redox-active polymers (RAPs) to improve their performance in applications such as catalysis, energy storage, and sensing. However, few studies systematically modify the redox loading through copolymerization to understand the impact on the polymer electrochemistry. In this study, we developed a series of (co)polymers incorporating redox-active ferrocene motif and nonredox-active, polyethylene glycol-type Jeffamine diluent, using ring-opening metathesis polymerization (ROMP). The redox activity and charge transfer characteristics of the resulting (co)polymers were successfully modulated by systematically varying the ratios of the two monomers, where elemental analysis and ultraviolet–visible (UV–vis) spectroscopy quantitatively confirmed their composition. Cyclic voltammetry (CV) analysis of films deposited and operated in different conditions for samples synthesized with 25% to 100% of the ferrocene repeat unit confirmed the ability to fine-tune redox behavior, including interchain interactions. Furthermore, experiments at varying ionic strength and (co)polymer composition revealed distinct interactions with ions in the supporting electrolyte, as probed via in situ infrared spectroscopy. The behavior of polymers in solution, characterized via bulk electrolysis and UV–vis spectroscopy, was compared to that in films, highlighting the role of Jeffamine in decreasing interactions responsible for distortions in the film CV and polymer insolubility in their oxidized form. This approach of incorporating nonredox-active monomers to modulate redox and ionic interactions could be applied to other combinations of polymers and redox-active molecules, offering a strategic approach to tailor properties such as solubility, charge accessibility, and rate in redox polymers for diverse applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"10 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641039","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":"Morphological Transitions and Chain Conformations in AB2 Miktoarm Star Block Copolymers: A Molecular Dynamics Study","authors":"Zerihun G. Workineh, Farzad Toiserkani, Joshua Lequieu, Giuseppe Pellicane, Mesfin Tsige","doi":"10.1021/acs.macromol.5c00029","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00029","url":null,"abstract":"This study investigates the role of chain architecture and block asymmetry on the morphology of <i>AB</i>₂ miktoarm star block copolymers (<i>AB</i>₂ BCPs) in the strongly segregated regime using molecular dynamics simulations. Notably, the cylindrical morphology in <i>AB</i>₂ BCPs persists across a broad compositional range, extending close to <i>f</i>_<i>A</i> ≈ 0.5, in agreement with both theoretical and experimental findings. The lamellar morphology observed up to <i>f</i>_<i>A</i> ≈ 0.8 matches predictions; however, beyond this point, <i>AB</i>₂ BCPs continue to exhibit lamellar structures (disk-like micelles), deviating from the expected transitions to cylindrical or spherical morphologies. This behavior, corroborated by dissipative particle dynamics simulations, is attributed to the B arms’ preference to occupying the outer regions of curved interfaces, which hinders the formation of cylindrical or spherical morphologies. Furthermore, domain spacing results exhibit remarkable agreement with strong-stretching theory (SST) across different morphologies, reinforcing the predictive power of SST. Finally, shape parameter analysis, including metrics like asphericity and acylindricity, underscores the significant impact of chain architecture on these morphological transitions. These findings provide molecular-level insights into how chain architecture and block asymmetry dictate phase behavior and morphological stability in linear and miktoarm BCPs.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"4 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143635487","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":"Brittle-to-Ductile Transitions of Polyelectrolyte Complexes: Humidity, Temperature, and Salt","authors":"Isaac A. Ramírez Marrero, Nadine Kaiser, Bernhard von Vacano, Rupert Konradi, Alfred J. Crosby, Sarah L. Perry","doi":"10.1021/acs.macromol.4c02819","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02819","url":null,"abstract":"Polyelectrolyte complexation is an entropically driven, associative phase separation that results in a polymer-rich polyelectrolyte complex (PEC) and a polymer-poor supernatant. PECs show promise as a new class of sustainable materials since they can be processed using aqueous solutions rather than organic solvents. Previous reports have looked at the mechanical properties and glass transitions of PECs as a function of temperature, relative humidity (rH), and salt concentration (C_S), but establishing a universal understanding of how these parameters affect PEC mechanics has yet to be achieved. We examined the effects of temperature, rH, and C_S on the mechanical properties of PECs formed from poly(methacrylic acid) and poly(trimethyl aminoethyl methacrylate) with a goal of establishing design rules for their mechanical response. Relative humidity was shown to have the most dramatic effect on the mechanical properties, with temperature and salt concentration having far less of an impact. Furthermore, we observed that the glass transition of PECs is tied to both temperature and relative humidity, creating a glass transition rH_g/<i>T</i>_g line that can be modulated by added salt. Finally, we looked at the thermodynamics behind the glass transition of PECs, which yielded similar energies as the condensation of water. We propose the use of water and/or salt as a low energy and efficient method of processing PECs for various applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"33 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143635396","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":"Morphological Transitions and Chain Conformations in AB2 Miktoarm Star Block Copolymers: A Molecular Dynamics Study","authors":"Zerihun G. Workineh,&nbsp;Farzad Toiserkani,&nbsp;Joshua Lequieu,&nbsp;Giuseppe Pellicane and Mesfin Tsige*,&nbsp;","doi":"10.1021/acs.macromol.5c0002910.1021/acs.macromol.5c00029","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00029https://doi.org/10.1021/acs.macromol.5c00029","url":null,"abstract":"<p >This study investigates the role of chain architecture and block asymmetry on the morphology of <i>AB</i>₂ miktoarm star block copolymers (<i>AB</i>₂ BCPs) in the strongly segregated regime using molecular dynamics simulations. Notably, the cylindrical morphology in <i>AB</i>₂ BCPs persists across a broad compositional range, extending close to <i>f</i>_<i>A</i> ≈ 0.5, in agreement with both theoretical and experimental findings. The lamellar morphology observed up to <i>f</i>_<i>A</i> ≈ 0.8 matches predictions; however, beyond this point, <i>AB</i>₂ BCPs continue to exhibit lamellar structures (disk-like micelles), deviating from the expected transitions to cylindrical or spherical morphologies. This behavior, corroborated by dissipative particle dynamics simulations, is attributed to the B arms’ preference to occupying the outer regions of curved interfaces, which hinders the formation of cylindrical or spherical morphologies. Furthermore, domain spacing results exhibit remarkable agreement with strong-stretching theory (SST) across different morphologies, reinforcing the predictive power of SST. Finally, shape parameter analysis, including metrics like asphericity and acylindricity, underscores the significant impact of chain architecture on these morphological transitions. These findings provide molecular-level insights into how chain architecture and block asymmetry dictate phase behavior and morphological stability in linear and miktoarm BCPs.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 6","pages":"3343–3354 3343–3354"},"PeriodicalIF":5.1,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678591","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":"Brittle-to-Ductile Transitions of Polyelectrolyte Complexes: Humidity, Temperature, and Salt","authors":"Isaac A. Ramírez Marrero,&nbsp;Nadine Kaiser,&nbsp;Bernhard von Vacano,&nbsp;Rupert Konradi,&nbsp;Alfred J. Crosby and Sarah L. Perry*,&nbsp;","doi":"10.1021/acs.macromol.4c0281910.1021/acs.macromol.4c02819","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02819https://doi.org/10.1021/acs.macromol.4c02819","url":null,"abstract":"<p >Polyelectrolyte complexation is an entropically driven, associative phase separation that results in a polymer-rich polyelectrolyte complex (PEC) and a polymer-poor supernatant. PECs show promise as a new class of sustainable materials since they can be processed using aqueous solutions rather than organic solvents. Previous reports have looked at the mechanical properties and glass transitions of PECs as a function of temperature, relative humidity (rH), and salt concentration (C_S), but establishing a universal understanding of how these parameters affect PEC mechanics has yet to be achieved. We examined the effects of temperature, rH, and C_S on the mechanical properties of PECs formed from poly(methacrylic acid) and poly(trimethyl aminoethyl methacrylate) with a goal of establishing design rules for their mechanical response. Relative humidity was shown to have the most dramatic effect on the mechanical properties, with temperature and salt concentration having far less of an impact. Furthermore, we observed that the glass transition of PECs is tied to both temperature and relative humidity, creating a glass transition rH_g/<i>T</i>_g line that can be modulated by added salt. Finally, we looked at the thermodynamics behind the glass transition of PECs, which yielded similar energies as the condensation of water. We propose the use of water and/or salt as a low energy and efficient method of processing PECs for various applications.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 6","pages":"2925–2938 2925–2938"},"PeriodicalIF":5.1,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678590","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":"Resolving the Mystery of the Extraordinary Polyelectrolyte Behavior (Anomalously Slow Diffusive Mode) after Half-Century of Research","authors":"Marián Sedlák","doi":"10.1021/acs.macromol.4c03019","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03019","url":null,"abstract":"Half a century ago, the presence of an anomalously slow diffusive mode in polyelectrolyte solutions (extraordinary behavior) was mentioned for the first time. The transition from high-salt to low-salt conditions was referred to as the “ordinary–extraordinary transition.” It was related to the appearance of large structures in solution appreciably exceeding the sizes of individual polyions despite like-charges on polyions and monovalent counterions. Despite appreciable experimental effort, no clear explanation of the origin of this phenomenon was reached, while existing theories of like-charge attraction were not able to explain experimental data. This work brings a resolution to this long-standing puzzle, although some questions remain still open. It is shown that there are two types of submicrometer-sized objects that occur simultaneously in polyelectrolyte solutions and contribute to the slow diffusive mode. Since their size distributions are very similar, it was not possible to identify them so far on the basis of simple scattering experiments. The first type of object originates from hydrophobic molecules commonly present in polyelectrolytes as unwanted admixtures, which (1) adhere to uncharged polymer chains; (2) are stripped from the chains upon ionization; (3) aggregate in water; and (4) the aggregation process stops at a mesoscale level because of developing a surface ζ-potential. These mesoscale particles/droplets can then be removed from solution by filtration, providing a practical method for the purification of polyelectrolytes to ultrahigh purity. Objects of the second type occur even in solutions of hydrophobe-free polyelectrolytes and give a substantially weaker scattering signal. Their unexpected characteristics are described, but still more data are needed to exactly unveil their origin. This work brings a new paradigm in the interpretation of older and future data, realizing that the acquired data represent mostly a mixture of contributions from two different mechanisms, which must be separated in order to be meaningfully analyzed and interpreted. Experiments in this work were performed on synthetic polyelectrolytes representing polyanions, polycations, strong polyelectrolytes, and weak polyelectrolytes, respectively.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"183 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143635397","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":"Macroporous Polymers with Interconnectivity Gradients: Photopolymerization of Emulsion Templates Controlled by Height-Dependent Light Intensity","authors":"DongGeun Oh, Subeen Kim, Eungi Lee, ARa Jung, Jongmin Q. Kim, Jihoon Shin, KyuHan Kim","doi":"10.1021/acs.macromol.4c02999","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02999","url":null,"abstract":"Gradient porous polymers are engineered to vary the pore size, porosity, and interconnectivity in a single direction, enabling controlled mass transport and mechanical properties. This unique design makes them ideal candidates for applications in tissue engineering scaffolds, advanced filtration systems, and absorbent materials for environmental remediation. While various methods have been developed to create porous polymers with gradients in pore size and porosity, techniques for generating openness gradients remain largely unexplored. In this study, we present a novel approach for producing porous materials with a gradient openness through the photopolymerization of emulsion templates. By modulating the light intensity across the height of the emulsion templates during the photopolymerization process, we induce a gradual change in openness within polymerized high internal phase emulsions (polyHIPEs). This effect arises from the interplay between interfacial and bulk polymerization, influenced by the partitioning behavior of photoinitiators in the continuous phase, light intensity, and distance from the light source. Stronger light sources enhance the openness and produce more pronounced openness gradients. The progressive attenuation of light within the emulsion templates is primarily governed by UV transparency, which is controlled by incorporating different radical monomers, such as acrylic acid and acrylamide. This single-step process allows for the fabrication of porous polymers with precisely tuned mass transfer properties through controlled interconnectivity gradients.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"6 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143627653","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":"Renewable Lactam Monomer for Tunable and Processable Polyamides","authors":"Satu Häkkinen, Daniel M. Krajovic, Kari M. Chamberlain, Joshua Shippee, Arpan Biswas, Honghu Zhang, Lillian M. Felsenthal, William R. Dichtel, Marc A. Hillmyer","doi":"10.1021/acs.macromol.4c03199","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03199","url":null,"abstract":"Replacement of petroleum-derived monomers with renewable alternatives is an integral part of the sustainable polymer framework. Research in this area involves the search for bio-based or recycled starting materials for traditional polymers, as well as investigations into new materials accessible from renewable feedstocks. Focusing on the latter, we studied the properties of polyamides synthesized from γ-methyl-ε-caprolactam through anionic ring-opening polymerization by an activated monomer mechanism. The amorphous homopolymer presents high stiffness (Young’s modulus, ≈3 GPa), strength (stress at break, ≈80 MPa) and toughness under dry (low humidity) conditions, high ductility (strain at break, ≈1100%) in humid environments, optical clarity, and excellent processability due to its non-crystallizable nature and solubility in common organic solvents. Copolymerization with ε-caprolactam allows tailoring the mechanical properties and crystallinity in the resultant copolymers and provides new opportunities for advanced manufacturing and other applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"17 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143627654","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":"Squaraine Dyes as Efficient Photoredox Catalysts for PET-RAFT Polymerization in Batch and Flow Modes Accelerated by Suppression of Dye Aggregation","authors":"Anil M. Patil,&nbsp;Indrajeet S. Nawghare,&nbsp;Jayaraj Nithyanandhan* and Ashootosh V. Ambade*,&nbsp;","doi":"10.1021/acs.macromol.4c0261210.1021/acs.macromol.4c02612","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02612https://doi.org/10.1021/acs.macromol.4c02612","url":null,"abstract":"<p >Organic photoredox catalysts (PCs) based on squaraine dyes are investigated for photoinduced electron transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization under visible-light (λ_max = 485 nm) irradiation in the presence of triethylamine that suppresses self-aggregation of dye and accelerates the polymerization. Several commonly used PCs are also screened, and self-aggregation is found to be reduced with triethylamine, thus providing a simple and effective approach to reduce aggregation of PCs. There is no induction period, and total polymerization time is shorter for squaraine dye PCs than for reported PCs under similar conditions. The photocatalyst system is amenable to polymerization by using different RAFT agents. Methyl methacrylate and a range of functional methacrylates are polymerized with good control over molecular weight and narrow dispersity in a first-order reaction with a random switch “ON-OFF” of the light source and even without an inert atmosphere. The mechanism of polymerization without and with requirement of triethylamine is elucidated using control experiments and found to be an oxidative and reductive electron transfer, respectively. A series of diblock and random copolymers of methyl methacrylate with methacrylate monomers are synthesized. Controlled polymerization is also demonstrated using a continuous-flow method and in an aqueous medium.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 6","pages":"2850–2859 2850–2859"},"PeriodicalIF":5.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678469","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}