ACS polymers Au最新文献

{"title":"Exploring the Role of Hydroxy- and Phosphate-Terminated cis-1,4-Polyisoprene Chains in the Formation of Physical Junction Points in Natural Rubber: Insights from Molecular Dynamics Simulations","authors":"Mayank Dixit*,&nbsp; and ,&nbsp;Takashi Taniguchi*,&nbsp;","doi":"10.1021/acspolymersau.4c0001910.1021/acspolymersau.4c00019","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00019https://doi.org/10.1021/acspolymersau.4c00019","url":null,"abstract":"<p >This study elucidates the pivotal role of terminal structures in <i>cis</i>-1,4-polyisoprene (PI) chains, contributing to the exceptional mechanical properties of Hevea natural rubber (NR). NR’s unique networking structure, crucial for crack resistance, elasticity, and strain-induced crystallization, involves two terminal groups, ω and α. The proposed ω terminal structure is dimethyl allyl-(<i>trans</i>-1,4-isoprene)₂, and α terminals exist in various forms, including hydroxy, ester, and phosphate groups. Among others, we investigated three types of <i>cis</i>-1,4-PI with different terminal combinations: _HPI_H (pure PI with H terminal), _ωPI_α6 (PI with ω and α6 terminals), and _ωPI_PO₄ (PI with ω and PO₄ terminals) and revealed significant dynamics variations. Hydrogen bonds between α6 and α6 and PO₄ and PO₄ residues in _ωPI_α6 and _ωPI_PO₄ systems induce slower dynamics of hydroxy- and phosphate-terminated PI chains. Associations between α6 and α6 and PO₄ and PO₄ terminals are markedly stronger than ω and ω, and hydrogen terminals in _HPI_H and _<i>ω</i>PI_α6,PO₄ systems. Phosphate terminals exhibit a stronger mutual association than hydroxy terminals. Potentials of mean force analysis and cluster-formation-fraction computations reveal stable clusters in _ωPI_α6 and _ωPI_PO₄, supporting the formation of polar aggregates (physical junction points). Notably, phosphate terminal groups facilitate large and highly stable phosphate polar aggregates, crucial for the natural networking structure responsible for NR’s outstanding mechanical properties compared to synthetic PI rubber. This comprehensive investigation provides valuable insights into the role of terminal groups in <i>cis</i>-1,4-PI melt systems and their profound impact on the mechanical properties of NR.</p>","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"4 4","pages":"273–288 273–288"},"PeriodicalIF":4.7,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acspolymersau.4c00019","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141977812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pattern Formation in Evaporating Polymer Solutions─Interplay between Dewetting and Decomposition","authors":"Pankaj Mahawar, M. Praveena, Shreyanil Bhuyan, Dipin S. Pillai, Sivasurender Chandran","doi":"10.1021/acspolymersau.4c00018","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00018","url":null,"abstract":"Pattern formation during solution evaporation is common in several industrial settings and involves a complex interplay of multiple processes, including wetting/dewetting, diffusion, and rheological characteristics of the solution. Monitoring the emergence of patterns during evaporation under controlled conditions may allow deconvolution of different processes and, in turn, improve our understanding of this common yet complex phenomenon. Here, we probe the importance of initial conditions, defined by the solution concentration <i>c</i>₀, on the pattern formation in evaporating polymer solutions on the air–water interface. Intriguingly, the initial decrease in the lateral length scale (ξ), characterizing the patterns, takes an upturn at higher concentrations, revealing reentrant behavior. We employ a gradient dynamics model consisting of coupled evolution equations for the film height and the polymer fraction in the solution. Our simulations capture two different length scales revealing the reasons underlying the re-entrant behavior of ξ(<i>c</i>₀). While the long-range destabilizing interactions between suspension and water result in the dewetting of thin film solutions, the phase separation between the polymer and solvent occurs at shorter length scales. Our results demonstrate the importance of initial concentration on pattern formation and, thereby, on the resultant properties of thin polymer films.","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140934637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pattern Formation in Evaporating Polymer Solutions─Interplay between Dewetting and Decomposition","authors":"Pankaj Mahawar,&nbsp;M. Praveena,&nbsp;Shreyanil Bhuyan,&nbsp;Dipin S. Pillai and Sivasurender Chandran*,&nbsp;","doi":"10.1021/acspolymersau.4c0001810.1021/acspolymersau.4c00018","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00018https://doi.org/10.1021/acspolymersau.4c00018","url":null,"abstract":"<p >Pattern formation during solution evaporation is common in several industrial settings and involves a complex interplay of multiple processes, including wetting/dewetting, diffusion, and rheological characteristics of the solution. Monitoring the emergence of patterns during evaporation under controlled conditions may allow deconvolution of different processes and, in turn, improve our understanding of this common yet complex phenomenon. Here, we probe the importance of initial conditions, defined by the solution concentration <i>c</i>₀, on the pattern formation in evaporating polymer solutions on the air–water interface. Intriguingly, the initial decrease in the lateral length scale (ξ), characterizing the patterns, takes an upturn at higher concentrations, revealing reentrant behavior. We employ a gradient dynamics model consisting of coupled evolution equations for the film height and the polymer fraction in the solution. Our simulations capture two different length scales revealing the reasons underlying the re-entrant behavior of ξ(<i>c</i>₀). While the long-range destabilizing interactions between suspension and water result in the dewetting of thin film solutions, the phase separation between the polymer and solvent occurs at shorter length scales. Our results demonstrate the importance of initial concentration on pattern formation and, thereby, on the resultant properties of thin polymer films.</p>","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"4 4","pages":"302–310 302–310"},"PeriodicalIF":4.7,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acspolymersau.4c00018","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141977811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Real-Time Determination of Molecular Weight: Use of MaDDOSY (Mass Determination Diffusion Ordered Spectroscopy) to Monitor the Progress of Polymerization Reactions","authors":"Owen Tooley, William Pointer, Rowan Radmall, Mia Hall, Thomas Swift, James Town, Cansu Aydogan, Tanja Junkers, Paul Wilson, Daniel Lester, David Haddleton","doi":"10.1021/acspolymersau.4c00020","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00020","url":null,"abstract":"Knowledge of molecular weight is an integral factor in polymer synthesis, and while many synthetic strategies have been developed to help control this, determination of the final molecular weight is often only measured at the end of the reaction. Herein, we provide a technique for the online determination of polymer molecular weight using a universal, solvent-independent diffusion ordered spectroscopy (DOSY) calibration and evidence its use in a variety of polymerization reactions.","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140934551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Real-Time Determination of Molecular Weight: Use of MaDDOSY (Mass Determination Diffusion Ordered Spectroscopy) to Monitor the Progress of Polymerization Reactions","authors":"Owen Tooley,&nbsp;William Pointer,&nbsp;Rowan Radmall,&nbsp;Mia Hall,&nbsp;Thomas Swift,&nbsp;James Town,&nbsp;Cansu Aydogan,&nbsp;Tanja Junkers,&nbsp;Paul Wilson,&nbsp;Daniel Lester* and David Haddleton*,&nbsp;","doi":"10.1021/acspolymersau.4c0002010.1021/acspolymersau.4c00020","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00020https://doi.org/10.1021/acspolymersau.4c00020","url":null,"abstract":"<p >Knowledge of molecular weight is an integral factor in polymer synthesis, and while many synthetic strategies have been developed to help control this, determination of the final molecular weight is often only measured at the end of the reaction. Herein, we provide a technique for the online determination of polymer molecular weight using a universal, solvent-independent diffusion ordered spectroscopy (DOSY) calibration and evidence its use in a variety of polymerization reactions.</p>","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"4 4","pages":"311–319 311–319"},"PeriodicalIF":4.7,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acspolymersau.4c00020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141977817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Finding Professional Growth and Fulfillment for Early-Career Polymer Scientists and Engineers in Industry","authors":"Jeffrey M. Ting,&nbsp; and ,&nbsp;Michael B. Sims,&nbsp;","doi":"10.1021/acspolymersau.4c00039","DOIUrl":"10.1021/acspolymersau.4c00039","url":null,"abstract":"","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"4 3","pages":"157–167"},"PeriodicalIF":0.0,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acspolymersau.4c00039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140934635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Polymer Architecture and Charged Molecular Crowders on Hydrophobic Polymer Collapse","authors":"Satyendra Rajput,&nbsp; and ,&nbsp;Divya Nayar*,&nbsp;","doi":"10.1021/acspolymersau.4c0001110.1021/acspolymersau.4c00011","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00011https://doi.org/10.1021/acspolymersau.4c00011","url":null,"abstract":"<p >Accounting for the crowding effects inside a living cell is crucial to obtain a comprehensive view of the biomolecular processes and designing responsive polymer-based materials for biomedical applications. These effects have long been synonymous with the entropic volume exclusion effects. The role of soft, attractive intermolecular interactions remains elusive. Here, we investigate the effects of model cationic and anionic hydrophobic molecular crowders on the collapse equilibrium of uncharged model polymers using molecular dynamics simulations. Particularly, the effect of polymer architecture is explored where a 50-bead linear polymer model (Poly-I) and a branched polymer model (Poly-II) with nonpolar side chains are examined. The collapse of Poly-I is found to be highly favorable than in Poly-II in neat water. Addition of anionic crowders strengthens hydrophobic collapse in Poly-I, whereas collapse of Poly-II is only slightly favored over that in neat water. The thermodynamic driving forces are quite distinct in water. Collapse of Poly-I is driven by the favorable polymer–solvent entropy change (due to loss of waters to bulk on collapse), whereas collapse of Poly-II is driven by the favorable polymer–solvent energy change (due to favorable intrapolymer energy). The anionic crowders support the entropic mechanism for Poly-I by acting like surfactants, redirecting water dipoles toward themselves, and preferentially adsorbing on the Poly-I surface. In the case of Poly-II, the anionic crowders are loosely bound to polymer side chains, and loss of crowders and waters to the bulk on polymer collapse reduces the entropic penalty, thereby making collapse free energy slightly more favorable than in neat water. The results indicate the discriminating behavior of anionic crowders to strengthen the hydrophobic collapse. It is related to the structuring of water molecules around the termini and the central region of the two polymers. The results address the modulation of hydrophobic hydration by weakly hydrated ionic hydrophobes at crowded concentrations.</p>","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"4 4","pages":"289–301 289–301"},"PeriodicalIF":4.7,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acspolymersau.4c00011","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141977816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Polymer Architecture and Charged Molecular Crowders on Hydrophobic Polymer Collapse","authors":"Satyendra Rajput, Divya Nayar","doi":"10.1021/acspolymersau.4c00011","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00011","url":null,"abstract":"Accounting for the crowding effects inside a living cell is crucial to obtain a comprehensive view of the biomolecular processes and designing responsive polymer-based materials for biomedical applications. These effects have long been synonymous with the entropic volume exclusion effects. The role of soft, attractive intermolecular interactions remains elusive. Here, we investigate the effects of model cationic and anionic hydrophobic molecular crowders on the collapse equilibrium of uncharged model polymers using molecular dynamics simulations. Particularly, the effect of polymer architecture is explored where a 50-bead linear polymer model (Poly-I) and a branched polymer model (Poly-II) with nonpolar side chains are examined. The collapse of Poly-I is found to be highly favorable than in Poly-II in neat water. Addition of anionic crowders strengthens hydrophobic collapse in Poly-I, whereas collapse of Poly-II is only slightly favored over that in neat water. The thermodynamic driving forces are quite distinct in water. Collapse of Poly-I is driven by the favorable polymer–solvent entropy change (due to loss of waters to bulk on collapse), whereas collapse of Poly-II is driven by the favorable polymer–solvent energy change (due to favorable intrapolymer energy). The anionic crowders support the entropic mechanism for Poly-I by acting like surfactants, redirecting water dipoles toward themselves, and preferentially adsorbing on the Poly-I surface. In the case of Poly-II, the anionic crowders are loosely bound to polymer side chains, and loss of crowders and waters to the bulk on polymer collapse reduces the entropic penalty, thereby making collapse free energy slightly more favorable than in neat water. The results indicate the discriminating behavior of anionic crowders to strengthen the hydrophobic collapse. It is related to the structuring of water molecules around the termini and the central region of the two polymers. The results address the modulation of hydrophobic hydration by weakly hydrated ionic hydrophobes at crowded concentrations.","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140883549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclodextrin-Induced Suppression of the Crystallization of Low-Molar-Mass Poly(ethylene glycol)","authors":"Ian W. Hamley, Valeria Castelletto","doi":"10.1021/acspolymersau.4c00024","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00024","url":null,"abstract":"We examine the effect of alpha-cyclodextrin (αCD) on the crystallization of poly(ethylene glycol) (PEG) [poly(ethylene oxide), PEO] in low-molar-mass polymers, with <i>M</i>_w = 1000, 3000, or 6000 g mol^–1. Differential scanning calorimetry (DSC) and simultaneous synchrotron small-/wide-angle X-ray scattering (SAXS/WAXS) show that crystallization of PEG is suppressed by αCD, provided that the cyclodextrin content is sufficient. The PEG crystal structure is replaced by a hexagonal mesophase of αCD-threaded polymer chains. The αCD threading reduces the conformational flexibility of PEG and, hence, suppresses crystallization. These findings point to the use of cyclodextrin additives as a powerful means to tune the crystallization of PEG (PEO), which, in turn, will impact bulk properties including biodegradability.","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140838071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyclodextrin-Induced Suppression of the Crystallization of Low-Molar-Mass Poly(ethylene glycol)","authors":"Ian W. Hamley*,&nbsp; and ,&nbsp;Valeria Castelletto,&nbsp;","doi":"10.1021/acspolymersau.4c0002410.1021/acspolymersau.4c00024","DOIUrl":"https://doi.org/10.1021/acspolymersau.4c00024https://doi.org/10.1021/acspolymersau.4c00024","url":null,"abstract":"<p >We examine the effect of alpha-cyclodextrin (αCD) on the crystallization of poly(ethylene glycol) (PEG) [poly(ethylene oxide), PEO] in low-molar-mass polymers, with <i>M</i>_w = 1000, 3000, or 6000 g mol^–1. Differential scanning calorimetry (DSC) and simultaneous synchrotron small-/wide-angle X-ray scattering (SAXS/WAXS) show that crystallization of PEG is suppressed by αCD, provided that the cyclodextrin content is sufficient. The PEG crystal structure is replaced by a hexagonal mesophase of αCD-threaded polymer chains. The αCD threading reduces the conformational flexibility of PEG and, hence, suppresses crystallization. These findings point to the use of cyclodextrin additives as a powerful means to tune the crystallization of PEG (PEO), which, in turn, will impact bulk properties including biodegradability.</p>","PeriodicalId":72049,"journal":{"name":"ACS polymers Au","volume":"4 4","pages":"266–272 266–272"},"PeriodicalIF":4.7,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.acs.org/doi/epdf/10.1021/acspolymersau.4c00024","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141977813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}