Macromolecules最新文献

{"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}

{"title":"Renewable Lactam Monomer for Tunable and Processable Polyamides","authors":"Satu Häkkinen,&nbsp;Daniel M. Krajovic,&nbsp;Kari M. Chamberlain,&nbsp;Joshua Shippee,&nbsp;Arpan Biswas,&nbsp;Honghu Zhang,&nbsp;Lillian M. Felsenthal,&nbsp;William R. Dichtel and Marc A. Hillmyer*,&nbsp;","doi":"10.1021/acs.macromol.4c0319910.1021/acs.macromol.4c03199","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03199https://doi.org/10.1021/acs.macromol.4c03199","url":null,"abstract":"<p >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.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 6","pages":"3027–3037 3027–3037"},"PeriodicalIF":5.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678817","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":"Propagation of Dislocations and Stress Transmission in Poly(p-phenylene terephthalamide) (PPTA)","authors":"Ran Chen,&nbsp;Chuanfu Luo* and Xiaoniu Yang*,&nbsp;","doi":"10.1021/acs.macromol.5c0019310.1021/acs.macromol.5c00193","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00193https://doi.org/10.1021/acs.macromol.5c00193","url":null,"abstract":"<p >Dislocations play a crucial role in determining the deformation of materials yet are still rarely explored in polymers. Employing all-atom molecular dynamics simulations, we directly analyzed the unique structure of quasi-1D dislocations in poly(p-phenylene terephthalamide) (PPTA) induced by an external force, which is drastically different from those in metals. The propagation of dislocations in polymer fibers occurs in two distinct stages: the slow internal propagation and the subsequent rapid extension at chain ends. All results reveal that the ultimate strength of polymer fibers is determined by dislocations rather than breaking chemical bonds. The relationship between stress transmission and dislocation propagation reveals that dislocations are caused by localized motion processes, necessitating a specific stress level to overcome the energy barrier associated with dislocations. The unique nature of dislocations in polymers transcends specific material categories, offering universally applicable insights, as verified by poly(p-phenylene terephthalamide) (PPTA), polyethylene (PE), and polyamide (PA6). Our results provide an in-depth understanding of the dislocation kinetics in polymers.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 6","pages":"3160–3167 3160–3167"},"PeriodicalIF":5.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678476","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,&nbsp;Subeen Kim,&nbsp;Eungi Lee,&nbsp;ARa Jung,&nbsp;Jongmin Q. Kim,&nbsp;Jihoon Shin* and KyuHan Kim*,&nbsp;","doi":"10.1021/acs.macromol.4c0299910.1021/acs.macromol.4c02999","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02999https://doi.org/10.1021/acs.macromol.4c02999","url":null,"abstract":"<p >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.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 6","pages":"3278–3288 3278–3288"},"PeriodicalIF":5.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143678891","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, Indrajeet S. Nawghare, Jayaraj Nithyanandhan, Ashootosh V. Ambade","doi":"10.1021/acs.macromol.4c02612","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02612","url":null,"abstract":"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.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"88 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143627777","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":"Acid-Catalyzed Interfacial Polymerization of a Benzimidazole-Linked Polymer Membrane for Efficient H2/CO2 Separation","authors":"Jingjing Zhang, Chaoqun Niu, Ning Ren, Jiahang Du, Meixia Shan, Roberto Castro-Muñoz, Yatao Zhang","doi":"10.1021/acs.macromol.4c02771","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02771","url":null,"abstract":"The development of cost-effective and energy-efficient membrane materials is of significant importance for the purification of hydrogen and the capture of carbon dioxide. Given the potential of benzimidazole-linked polymers (BILPs) for H₂/CO₂ separation, this study aimed to synthesize a novel BILP membrane material (BILP-x) through an acid-catalyzed interfacial polymerization strategy. The BILP-x membranes achieved an exceptional H₂ permeance of 176.6 GPU and a H₂/CO₂ selectivity of 12.3 at room temperature. Decreasing the BTA concentration can significantly increase the H₂ permeance to 987.6 GPU, while the H₂/CO₂ selectivity decreased to 8.0 at room temperature. In addition, the BILP-x membrane demonstrated exceptional long-term stability in H₂/CO₂ separation, maintaining its performance for up to 300 h under alternating temperatures of 373 and 423 K. Meanwhile, the molecular dynamics simulations verified that the addition of acid accelerated the diffusion rate of TP molecules in the interfacial polymerization reaction, resulting in the formation of denser membranes. The finding not only validates the promise of BILP-x membranes for H₂/CO₂ separation, but also opens up a new avenue for the development of high-performance membrane materials for a range of separation applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"20 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143618798","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}