Pub Date : 2024-11-07DOI: 10.1021/acs.macromol.4c01494
Luofu Liu, Chao Duan, Rui Wang
Trapping macromolecules is important for the study of their conformations, interactions, dynamics, and kinetic processes. Here, we develop a new theory using a Gaussian variational approach to confine the center-of-mass of polymers. It self-consistently introduces a mean force that controls the average position of the center-of-mass and a self-adjustable harmonic potential that counters the fluctuation of the center-of-mass position. The effectiveness and versatility of our theory are verified in three classical yet not fully understood problems in polymer science: (1) single-chain conformation in the whole regime of solvent quality, (2) globule-pearl necklace-coil transition of a polyelectrolyte, and (3) interchain interaction by simultaneously confining two polymers. The scaling relationships and θ behaviors are well captured. Conformations with large shape anisotropies appearing in charged polymers are clearly depicted. Being a field theoretical framework, our theory also facilitates visualization of the conformational response and kinetic process. Our theoretical prediction of the radius of gyration of poly(N-isopropylacrylamide) (PNIPAM) is in quantitative agreement with experimental results reported in the literature.
{"title":"A Variational Field-Theoretical Approach to Control the Center-Of-Mass of Macromolecules","authors":"Luofu Liu, Chao Duan, Rui Wang","doi":"10.1021/acs.macromol.4c01494","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01494","url":null,"abstract":"Trapping macromolecules is important for the study of their conformations, interactions, dynamics, and kinetic processes. Here, we develop a new theory using a Gaussian variational approach to confine the center-of-mass of polymers. It self-consistently introduces a mean force that controls the average position of the center-of-mass and a self-adjustable harmonic potential that counters the fluctuation of the center-of-mass position. The effectiveness and versatility of our theory are verified in three classical yet not fully understood problems in polymer science: (1) single-chain conformation in the whole regime of solvent quality, (2) globule-pearl necklace-coil transition of a polyelectrolyte, and (3) interchain interaction by simultaneously confining two polymers. The scaling relationships and θ behaviors are well captured. Conformations with large shape anisotropies appearing in charged polymers are clearly depicted. Being a field theoretical framework, our theory also facilitates visualization of the conformational response and kinetic process. Our theoretical prediction of the radius of gyration of poly(<i>N</i>-isopropylacrylamide) (PNIPAM) is in quantitative agreement with experimental results reported in the literature.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"33 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594232","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}
Pub Date : 2024-11-06DOI: 10.1021/acs.macromol.4c02102
Alexander Evans, Oliver Casale, Louis J. Morris, Zoë R. Turner, Dermot O’Hare
Functional polypropylenes (FPs) are regarded as versatile building blocks for next-generation materials; however, their development has been stymied due to current synthetic limitations. Here, we report a diverse range of functionalized polypropylenes prepared via a two-step copolymerization−postmodification strategy. Solution-phase copolymerization of propylene and 11-bromo-1-undecene using C2, C1, and Cs-symmetric catalysts-afforded poly(propylene)-co-(11-bromo-1-undecene), with tunable comonomer incorporation levels, up to 15.5 mol %, with a range of tacticities (iso-, syndio-, and atactic) and a wide molecular weight span (4−212 kg mol−1). The latent electrophilic reactivity of the pendent bromide has been utilized in one of three general synthetic routes, enabling the incorporation of an array of polar substituents through the formation of a series of covalent connections (C−O, C−N, C−S, C−P, and C−C). The resulting FPs display distinctly altered bulk and surface properties, compared to polypropylene: improved thermal stability and adhesion to metal, altered wettability, and latent reactivity. This strategy allows access to FPs with both high molecular weight and chosen tacticity, taking advantage of well-developed metallocene catalysts and classical organic substitution chemistry.
{"title":"Functionalized Polypropylenes: A Copolymerization and Postmodification Platform","authors":"Alexander Evans, Oliver Casale, Louis J. Morris, Zoë R. Turner, Dermot O’Hare","doi":"10.1021/acs.macromol.4c02102","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02102","url":null,"abstract":"Functional polypropylenes (FPs) are regarded as versatile building blocks for next-generation materials; however, their development has been stymied due to current synthetic limitations. Here, we report a diverse range of functionalized polypropylenes prepared via a two-step copolymerization−postmodification strategy. Solution-phase copolymerization of propylene and 11-bromo-1-undecene using <i>C</i><sub>2</sub>, <i>C</i><sub>1</sub>, and <i>C</i><sub><i>s</i></sub>-symmetric catalysts-afforded poly(propylene)-<i>co</i>-(11-bromo-1-undecene), with tunable comonomer incorporation levels, up to 15.5 mol %, with a range of tacticities (<i>iso-</i>, <i>syndio-</i>, and <i>atactic</i>) and a wide molecular weight span (4−212 kg mol<sup>−1</sup>). The latent electrophilic reactivity of the pendent bromide has been utilized in one of three general synthetic routes, enabling the incorporation of an array of polar substituents through the formation of a series of covalent connections (C−O, C−N, C−S, C−P, and C−C). The resulting FPs display distinctly altered bulk and surface properties, compared to polypropylene: improved thermal stability and adhesion to metal, altered wettability, and latent reactivity. This strategy allows access to FPs with both high molecular weight and chosen tacticity, taking advantage of well-developed metallocene catalysts and classical organic substitution chemistry.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"28 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142589203","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}
Organic mixed ionic-electronic conductors (OMIECs) play a fundamental role in the performance of organic electrochemical transistors (OECTs) and their applications. Although several depletion mode and accumulation mode OMIECs have been utilized for efficient OECT-based glucose sensors, there are still persistent drawbacks such as including biocompatibility, instability, or high detection limits. In this work, a series of indacenodithiophene-based polymeric OMIECs (gIDT, gIDT–T, and gIDT–DTBT) are developed, where the influences of backbone structure on their optical bandgap, energy level, electrochemical propriety, charge transfer and transistor performance, are systematically investigated. By applying KPF6 electrolyte and vertical device structure, gIDT–DTBT-based vertical OECTs (vOECTs) achieved a maximum output current of –15.63 mA, a maximum transconductance of 39.99 mS, and stable output current (less than ∼2% decay) over 1000 switching cycles. In addition, such vOECTs are employed to detect glucose concentrations ranging from 0.9 to 22.5 μM. A low limit of detection (0.1 μM) and good selectivity are demonstrated. This study indicates that the combination of regulating OMIECs’ backbone structure, selecting appropriate electrolytes, and implementing a vertical device structure can help optimize OECT performance and its biosensor applications.
{"title":"Backbone Engineering of Indacenodithiophene-Based Polymers for High-Performance Vertical Organic Electrochemical Transistors and Efficient Glucose Sensor","authors":"Yimin Sun, Yu Lan, Jiali Luo, Xiaokang Lu, Yueping Lai, Liang−Wen Feng, Ning Su, Jianhua Chen, Wei Huang, Hongxiang Li, Junqiao Ding","doi":"10.1021/acs.macromol.4c02129","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02129","url":null,"abstract":"Organic mixed ionic-electronic conductors (OMIECs) play a fundamental role in the performance of organic electrochemical transistors (OECTs) and their applications. Although several depletion mode and accumulation mode OMIECs have been utilized for efficient OECT-based glucose sensors, there are still persistent drawbacks such as including biocompatibility, instability, or high detection limits. In this work, a series of indacenodithiophene-based polymeric OMIECs (gIDT, gIDT–T, and gIDT–DTBT) are developed, where the influences of backbone structure on their optical bandgap, energy level, electrochemical propriety, charge transfer and transistor performance, are systematically investigated. By applying KPF<sub>6</sub> electrolyte and vertical device structure, gIDT–DTBT-based vertical OECTs (vOECTs) achieved a maximum output current of –15.63 mA, a maximum transconductance of 39.99 mS, and stable output current (less than ∼2% decay) over 1000 switching cycles. In addition, such vOECTs are employed to detect glucose concentrations ranging from 0.9 to 22.5 μM. A low limit of detection (0.1 μM) and good selectivity are demonstrated. This study indicates that the combination of regulating OMIECs’ backbone structure, selecting appropriate electrolytes, and implementing a vertical device structure can help optimize OECT performance and its biosensor applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"13 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142589204","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}
We propose an efficient method for the self-assembly of Gaussian block copolymers with general cyclic architectures and nonconcatenated ring block copolymer in a melt based on a Ginzburg–Landau-type density functional theory combined with random phase approximation. For the Gaussian copolymers, the applicability of the density functional theory is enhanced by a Gaussian embedding method with a graph Laplacian, which allows evaluating single-chain scattering functions for arbitrary architectures including internal multicycles without analytical difficulty. By using this methodology, we predict phase diagrams of ring and bicycle diblock copolymers at the same cost as a linear diblock copolymer, and discover various metastable morphologies of a tadpole triblock terpolymer, which have not been observed for linear and star triblock terpolymers. We also demonstrate that our framework predicts the phase diagram of the nonconcatenated ring diblock copolymer with the aid of its single-chain scattering function obtained by experiments.
{"title":"Density Functional Theory for Cyclic Block Copolymer Melts","authors":"Yoshinori Tomiyoshi, Takashi Honda, Toshihiro Kawakatsu, Takahiro Murashima, Erica Uehara, Tetsuo Deguchi","doi":"10.1021/acs.macromol.4c02003","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02003","url":null,"abstract":"We propose an efficient method for the self-assembly of Gaussian block copolymers with general cyclic architectures and nonconcatenated ring block copolymer in a melt based on a Ginzburg–Landau-type density functional theory combined with random phase approximation. For the Gaussian copolymers, the applicability of the density functional theory is enhanced by a Gaussian embedding method with a graph Laplacian, which allows evaluating single-chain scattering functions for arbitrary architectures including internal multicycles without analytical difficulty. By using this methodology, we predict phase diagrams of ring and bicycle diblock copolymers at the same cost as a linear diblock copolymer, and discover various metastable morphologies of a tadpole triblock terpolymer, which have not been observed for linear and star triblock terpolymers. We also demonstrate that our framework predicts the phase diagram of the nonconcatenated ring diblock copolymer with the aid of its single-chain scattering function obtained by experiments.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142580574","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}
Pub Date : 2024-11-05DOI: 10.1021/acs.macromol.4c01436
Joohyeong Park, Hyun Woo Cho
By employing parallel tempering molecular dynamics simulations with a bead-spring model, we investigate the universal scaling of interfacial thickness in polymer globules. Our findings reveal that while conventional predictions assuming a sharp interface effectively describe the transition in polymer size from coiled to globule states with temperature variations, they fail to capture the core density of the globules. This failure is attributed to a substantial interfacial thickness relative to the globule size, suggesting the existence of polymers in an intermediate regime before reaching fully collapsed states. Notably, the observed interfacial thickness displays universal scaling behaviors predicted by previous field-theoretical approaches, affirming the existence of a distinct intermediate globular regime identifiable by its unique scaling of interfacial thickness. We demonstrate that discrepancies in the scaling behavior of core density in intermediate regimes can be quantitatively accounted for by the universal scaling of interfacial thickness, highlighting the critical importance of considering interfacial thickness for a precise understanding of the conformations and associated structural properties of polymer globules.
{"title":"Universal Scaling Behaviors of Interfacial Thickness in Polymer Globules","authors":"Joohyeong Park, Hyun Woo Cho","doi":"10.1021/acs.macromol.4c01436","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01436","url":null,"abstract":"By employing parallel tempering molecular dynamics simulations with a bead-spring model, we investigate the universal scaling of interfacial thickness in polymer globules. Our findings reveal that while conventional predictions assuming a sharp interface effectively describe the transition in polymer size from coiled to globule states with temperature variations, they fail to capture the core density of the globules. This failure is attributed to a substantial interfacial thickness relative to the globule size, suggesting the existence of polymers in an intermediate regime before reaching fully collapsed states. Notably, the observed interfacial thickness displays universal scaling behaviors predicted by previous field-theoretical approaches, affirming the existence of a distinct intermediate globular regime identifiable by its unique scaling of interfacial thickness. We demonstrate that discrepancies in the scaling behavior of core density in intermediate regimes can be quantitatively accounted for by the universal scaling of interfacial thickness, highlighting the critical importance of considering interfacial thickness for a precise understanding of the conformations and associated structural properties of polymer globules.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"242 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142580622","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}
Star-shaped polymers have attracted attention due to their unique solution properties and viscosities. These effects are attributed to their hydrodynamic radii that differ significantly from those of linear polymers. The present study reports the synthesis of star-shaped helical polyacetylenes substituted with l-valine- and l-threonine-based optically active groups. The formation of star-shaped polymers was confirmed by size exclusion chromatography, solution viscosity, dynamic light scattering, and small-angle X-ray scattering measurements. The chiroptical intensities of the star-shaped polymers tended to be smaller than those of the corresponding linear polymers in solution but larger in the film state. The water contact angles and refractive indices of the star-shaped polymers were smaller than those of the linear polymers.
星形聚合物因其独特的溶液特性和粘度而备受关注。这些影响归因于它们的流体力学半径与线性聚合物有很大不同。本研究报告了用基于 l-缬氨酸和 l-苏氨酸的光学活性基团取代的星形螺旋聚乙炔的合成。通过尺寸排阻色谱法、溶液粘度、动态光散射和小角 X 射线散射测量，证实了星形聚合物的形成。星形聚合物的光强度在溶液中往往小于相应线性聚合物的光强度，但在薄膜状态下则较大。星形聚合物的水接触角和折射率均小于线形聚合物。
{"title":"Star-Shaped Polymers with Helical Polyacetylene Arms. Comparison of Solution- and Solid-State Properties with Linear Helical Polyacetylenes","authors":"Shota Mino, Kosuke Matsui, Masahide Goto, Akiyuki Ryoki, Takeyuki Suzuki, Kazushi Fujimoto, Hiromitsu Sogawa, Hiroto Kudo, Fumio Sanda","doi":"10.1021/acs.macromol.4c01509","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01509","url":null,"abstract":"Star-shaped polymers have attracted attention due to their unique solution properties and viscosities. These effects are attributed to their hydrodynamic radii that differ significantly from those of linear polymers. The present study reports the synthesis of star-shaped helical polyacetylenes substituted with <span>l</span>-valine- and <span>l</span>-threonine-based optically active groups. The formation of star-shaped polymers was confirmed by size exclusion chromatography, solution viscosity, dynamic light scattering, and small-angle X-ray scattering measurements. The chiroptical intensities of the star-shaped polymers tended to be smaller than those of the corresponding linear polymers in solution but larger in the film state. The water contact angles and refractive indices of the star-shaped polymers were smaller than those of the linear polymers.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"23 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142580572","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}
Pub Date : 2024-11-05DOI: 10.1021/acs.macromol.4c01955
Hongru Qiang, Xue Liang, Wenli Wang, Jiayun Jiang, Jianrui Li, Kai Hong, Jianzhong Du, Yunqing Zhu
Tishchenko reaction represents a highly atom-efficient method for synthesizing esters via aldehydes disproportionation, which holds significant promise in sustainable chemistry for polymerizing biorenewable dialdehydes into polyesters. However, previous Tishchenko polymerization attempts merely yielded oligomers with very low molecular weights due to intramolecular cyclization. To address this important challenge, we propose an efficient approach to leverage catalytic steric hindrance to achieve higher molecular weights. The investigation of six catalysts revealed that Al(OEt)3, with its three ethoxy groups initiating, imparts significant steric hindrance around the metal center and effectively prevents cyclization termination at the initial stage of polymerization, resulting in aromatic polyesters with a record Mw of 26.6 kg/mol. This breakthrough signals the potential of enhancing catalytic steric hindrance to overcome the low-molecular-weight limitation of Tishchenko polymerization. Building upon this discovery, we synthesized a series of biorenewable meta-substituted dialdehyde monomers (M1–M4) derived from vanillin to afford aromatic polyesters P(M1)–P(M4). These polymers offer tunable thermal properties through molecular weight and side chain flexibility adjustments, exhibiting high thermal stability (Td,5% > 208 °C) and controllable glass transition temperatures (1–58 °C), and are degradable under mild conditions. This work highlights the importance of developing new methods to utilize readily available bioderived molecules, which is of great value for the sustainable economy.
{"title":"Exploiting Catalytic Steric Hindrance for Enhanced Tishchenko Polymerization: Toward Biorenewable Aromatic Polyesters","authors":"Hongru Qiang, Xue Liang, Wenli Wang, Jiayun Jiang, Jianrui Li, Kai Hong, Jianzhong Du, Yunqing Zhu","doi":"10.1021/acs.macromol.4c01955","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01955","url":null,"abstract":"Tishchenko reaction represents a highly atom-efficient method for synthesizing esters <i>via</i> aldehydes disproportionation, which holds significant promise in sustainable chemistry for polymerizing biorenewable dialdehydes into polyesters. However, previous Tishchenko polymerization attempts merely yielded oligomers with very low molecular weights due to intramolecular cyclization. To address this important challenge, we propose an efficient approach to leverage catalytic steric hindrance to achieve higher molecular weights. The investigation of six catalysts revealed that Al(OEt)<sub>3</sub>, with its three ethoxy groups initiating, imparts significant steric hindrance around the metal center and effectively prevents cyclization termination at the initial stage of polymerization, resulting in aromatic polyesters with a record <i>M</i><sub>w</sub> of 26.6 kg/mol. This breakthrough signals the potential of enhancing catalytic steric hindrance to overcome the low-molecular-weight limitation of Tishchenko polymerization. Building upon this discovery, we synthesized a series of biorenewable meta-substituted dialdehyde monomers (<b>M1</b>–<b>M4</b>) derived from vanillin to afford aromatic polyesters P(<b>M1</b>)–P(<b>M4</b>). These polymers offer tunable thermal properties through molecular weight and side chain flexibility adjustments, exhibiting high thermal stability (<i>T</i><sub>d,5%</sub> > 208 °C) and controllable glass transition temperatures (1–58 °C), and are degradable under mild conditions. This work highlights the importance of developing new methods to utilize readily available bioderived molecules, which is of great value for the sustainable economy.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"34 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142580582","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}
Pub Date : 2024-11-04DOI: 10.1021/acs.macromol.4c01425
Krishna Vippala, Shreyas Shankar Wagle, Parul Rathee, Keerthana Mulamukkil, Yousif Ayoub, Arthur Komlosh, Sharon Gazal, Bianca Avramovitch, Roey J. Amir
In recent years, the development of nanoreactors, such as micellar nanoreactors (MNRs) for catalytic transformations, has gained significant attention due to their potential in enhancing reaction rates, selectivity, efficiency, and, as importantly, the ability to conduct organic chemistry in aqueous solutions. Among these, the copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction represents a pivotal transformation and is widely used in the synthesis of bioconjugates, pharmaceuticals, and advanced materials. This study aims toward advancing our understanding of the design and utilization of polymeric amphiphiles containing tris-triazole ligands as an integral element for CuAAC reactions within MNRs. Specifically, our investigation delves into three critical factors that influence the reaction rate within MNRs: hydrophobicity, architectural configuration of the polymeric ligands, and their concentration. Utilizing the high molecular precision of dendritic amphiphiles, we synthesized polymeric ligands with two distinct architectures, namely, PEG-ditris-triazole amphiphile (DTA) and PEG-monotris-triazole amphiphile (MTA), and explored their CuAAC reactivity through coassembly with commercially available Pluronic P123 amphiphiles. The results indicate that the architecture and the concentration of the polymeric ligands play more dominant roles in influencing the reaction rate than the hydrophobicity of the dendritic blocks. Notably, while MNRs assembled from solely DTA showed a dampened reaction rate, spiking P123 micelles with DTA yielded an MNR with significantly faster rates. Moreover, P123 MNRs spiked with the synthesized MTA demonstrated increased CuAAC reaction rates compared to those spiked with the DTA, and they even outperformed the widely used Tris(benzyltriazolylmethyl)amine ligand. These findings provide valuable insights into the design principles of polymer-based ligands for constructing reactive MNRs and other types of nanoreactors for efficient catalytic transformations.
{"title":"Micellar “Click” Nanoreactors: Spiking Pluronic-Based Micelles with Polymeric Ligands","authors":"Krishna Vippala, Shreyas Shankar Wagle, Parul Rathee, Keerthana Mulamukkil, Yousif Ayoub, Arthur Komlosh, Sharon Gazal, Bianca Avramovitch, Roey J. Amir","doi":"10.1021/acs.macromol.4c01425","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01425","url":null,"abstract":"In recent years, the development of nanoreactors, such as micellar nanoreactors (MNRs) for catalytic transformations, has gained significant attention due to their potential in enhancing reaction rates, selectivity, efficiency, and, as importantly, the ability to conduct organic chemistry in aqueous solutions. Among these, the copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) reaction represents a pivotal transformation and is widely used in the synthesis of bioconjugates, pharmaceuticals, and advanced materials. This study aims toward advancing our understanding of the design and utilization of polymeric amphiphiles containing tris-triazole ligands as an integral element for CuAAC reactions within MNRs. Specifically, our investigation delves into three critical factors that influence the reaction rate within MNRs: hydrophobicity, architectural configuration of the polymeric ligands, and their concentration. Utilizing the high molecular precision of dendritic amphiphiles, we synthesized polymeric ligands with two distinct architectures, namely, PEG-ditris-triazole amphiphile (DTA) and PEG-monotris-triazole amphiphile (MTA), and explored their CuAAC reactivity through coassembly with commercially available Pluronic P123 amphiphiles. The results indicate that the architecture and the concentration of the polymeric ligands play more dominant roles in influencing the reaction rate than the hydrophobicity of the dendritic blocks. Notably, while MNRs assembled from solely DTA showed a dampened reaction rate, spiking P123 micelles with DTA yielded an MNR with significantly faster rates. Moreover, P123 MNRs spiked with the synthesized MTA demonstrated increased CuAAC reaction rates compared to those spiked with the DTA, and they even outperformed the widely used Tris(benzyltriazolylmethyl)amine ligand. These findings provide valuable insights into the design principles of polymer-based ligands for constructing reactive MNRs and other types of nanoreactors for efficient catalytic transformations.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"195 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574590","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}
Improving the heat resistance of epoxy resins remains an important and challenging issue across a wide variety of applications. One strategy to address this challenge is the design of cured resins based on multifunctional epoxy. Compared to conventional difunctional epoxy resins, multifunctional epoxy resins are expected to easily form a highly cross-linking structure, which is anticipated to contribute to enhanced heat resistance. However, there is a lack of information about the detailed mechanisms of the formation of such cross-linking structures and their effects on the physical properties. We herein tracked the kinetics of curing reactions of difunctional and trifunctional epoxies with an amine hardener. Despite the identical reactivity of epoxy groups in both base monomers, the trifunctional epoxy system cured faster. In addition, in the difunctional epoxy system, gelation was followed by vitrification, while in the trifunctional epoxy system, gelation and vitrification occurred simultaneously. The accelerated curing reaction observed in the trifunctional epoxy system could be explained in terms of the localized temperature increase from the reaction heat, which subsequently accelerated the following reactions. The resulting post-cured trifunctional epoxy resin did not exhibit a clear glass transition. This, so-called Tg-less behavior was due to the glass transition temperature of the trifunctional epoxy unit being higher than its decomposition temperature. This mechanism for the Tg-less behavior, combined with the accelerated curing reactions, provides valuable insights for the design of thermosetting resins with enhanced thermal stability.
{"title":"Effect of Number Density of Epoxy Functional Groups on Reaction Kinetics for Epoxy Resin","authors":"Atsushi Tokunaga, Atsuomi Shundo, Riichi Kuwahara, Satoru Yamamoto, Keiji Tanaka","doi":"10.1021/acs.macromol.4c02178","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02178","url":null,"abstract":"Improving the heat resistance of epoxy resins remains an important and challenging issue across a wide variety of applications. One strategy to address this challenge is the design of cured resins based on multifunctional epoxy. Compared to conventional difunctional epoxy resins, multifunctional epoxy resins are expected to easily form a highly cross-linking structure, which is anticipated to contribute to enhanced heat resistance. However, there is a lack of information about the detailed mechanisms of the formation of such cross-linking structures and their effects on the physical properties. We herein tracked the kinetics of curing reactions of difunctional and trifunctional epoxies with an amine hardener. Despite the identical reactivity of epoxy groups in both base monomers, the trifunctional epoxy system cured faster. In addition, in the difunctional epoxy system, gelation was followed by vitrification, while in the trifunctional epoxy system, gelation and vitrification occurred simultaneously. The accelerated curing reaction observed in the trifunctional epoxy system could be explained in terms of the localized temperature increase from the reaction heat, which subsequently accelerated the following reactions. The resulting post-cured trifunctional epoxy resin did not exhibit a clear glass transition. This, so-called <i>T</i><sub>g</sub>-less behavior was due to the glass transition temperature of the trifunctional epoxy unit being higher than its decomposition temperature. This mechanism for the <i>T</i><sub>g</sub>-less behavior, combined with the accelerated curing reactions, provides valuable insights for the design of thermosetting resins with enhanced thermal stability.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"26 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574592","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}
Lewis pair polymerization (LPP) is an advanced polymerization technique known for its ability to synthesize ultrahigh-molecular-weight (UHMW) polymers under mild conditions with remarkable efficiency and precise control. In this study, a strong electron-donor ylide-functionalized phosphine, (1-(diethylphosphanyl)ethylidene)triphenyl-λ5-phosphane (YFP2), is introduced as a Lewis base (LB). It is combined with a sterically hindered moderately acidic Lewis acid (LA), (4-Me-2,6-tBu2-C6H2O)AliBu2 ((BHT)AliBu2), to prepare a frustrated Lewis pair (FLP) catalyst for the living methacrylates polymerization. The living character of this polymerization has been confirmed through various key observations: successful chain-extension experiments, a linear increase in the number-average molecular weight (Mn) of the polymer corresponding to monomer conversion and the ratio of monomer to initiator, and the development of distinct di- and triblock copolymers using different comonomer addition sequences. Importantly, this FLP catalyst system has successfully synthesized UHMW poly(methyl methacrylate) (PMMA) with Mn values reaching up to 2935 kg/mol and narrow molecular weight distribution (Đ) at room temperature (RT). This achievement establishes a new record for the highest reported Mn for PMMA using a living/controlled LPP system.
{"title":"Precise Access to Ultrahigh-Molecular-Weight Polymers by Ylide-Functionalized Phosphine-Based Frustrated Lewis Pairs","authors":"Yun Bai, Shiquan Li, Jianghua He, Changfei He, Yibao Li, Zhonggao Zhou, Yiwang Chen, Yuetao Zhang","doi":"10.1021/acs.macromol.4c01801","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01801","url":null,"abstract":"Lewis pair polymerization (LPP) is an advanced polymerization technique known for its ability to synthesize ultrahigh-molecular-weight (UHMW) polymers under mild conditions with remarkable efficiency and precise control. In this study, a strong electron-donor ylide-functionalized phosphine, (1-(diethylphosphanyl)ethylidene)triphenyl-λ<sup>5</sup>-phosphane (<b>YFP2</b>), is introduced as a Lewis base (LB). It is combined with a sterically hindered moderately acidic Lewis acid (LA), (4-Me-2,6-<i><sup>t</sup></i>Bu<sub>2</sub>-C<sub>6</sub>H<sub>2</sub>O)Al<i><sup>i</sup></i>Bu<sub>2</sub> ((BHT)Al<i><sup>i</sup></i>Bu<sub>2</sub>), to prepare a frustrated Lewis pair (FLP) catalyst for the living methacrylates polymerization. The living character of this polymerization has been confirmed through various key observations: successful chain-extension experiments, a linear increase in the number-average molecular weight (<i>M</i><sub>n</sub>) of the polymer corresponding to monomer conversion and the ratio of monomer to initiator, and the development of distinct di- and triblock copolymers using different comonomer addition sequences. Importantly, this FLP catalyst system has successfully synthesized UHMW poly(methyl methacrylate) (PMMA) with <i>M</i><sub>n</sub> values reaching up to 2935 kg/mol and narrow molecular weight distribution (<i>Đ</i>) at room temperature (RT). This achievement establishes a new record for the highest reported <i>M</i><sub>n</sub> for PMMA using a living/controlled LPP system.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"292 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142574591","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}
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