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Polymers
Special Issues
Cyclic Polymers
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Cyclic Polymers

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (31 May 2018) | Viewed by 38201

Special Issue Editors

Prof. Moonhor Ree

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Guest Editor
Department of Chemistry, Division of Advanced Materials Science, and Polymer Research Institute
Pohang University of Science and Technology, 77 Cheongam-ro (Hyoja-dong), Nam-gu, Pohang 37673, Korea
Interests: synthesis of functional and high performance polymers; structure, morphology, and surface/interface of polymers; properties of polymers; smart brush polymers and their nanostructures and applications; 3D structures of proteins and DNAs/RNAs; polymer and bioorganism interfaces and hybrid systems; synchrotron radiation science and its applications in polymers
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Toshifumi Satoh

E-Mail Website
Guest Editor
Division of Applied Chemistry, Laboratory of Polymer Chemistry, Faculty of Engineering, Hokkaido University, North 13 West 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
Interests: controlled/living polymerization systems; organocatalyzed polymerizations; architecturally complex polymers; unimolecular micelles; nanoparticles; microphase-separated structures; high performance polymers for memory devices; conductive polymers; stimuli-responsive polymers; carbohydrate polymers

Special Issue Information

Dear Colleagues,

Molecular topology has been a key aspect in numerous research topics of polymer science because of its impact on the physical properties of polymers. In particular, the emergence of various cyclic topologies based on linear polymers has recently drawn a great deal of attention from academia because of their unique traits, including increased glass transition temperatures, lower viscosity, and smaller hydrodynamic radius, due to there being no chain end group effect. As a result of research efforts, some cyclic polymers have been successfully prepared using two synthetic strategies, namely intramolecular ring closure reactions and ring expansion polymerizations. They were further characterized in terms of structure and properties. Nevertheless, such synthetic strategies are still facing some unsolved key issues, such as unreacted linear polymer precursor residue and its removal, side reaction products and their removal, low overall reaction yields, high time consumption, and limits in ring size (in ring expansion approach). Moreover, information on their structures and properties is very limited thus far. Overall, cyclic polymers are a very interesting and challenging research subjects in polymer science from the views of synthesis, structure, properties, and applications.

This Special Issue covers recent, advanced research progress in high purity and throughput synthesis, functionality, chemical structure, morphology, properties, and potential applications of cyclic polymers in various topologies. High-quality research articles, as well as reviews and feature articles, are welcome.

Prof. Moonhor Ree
Prof. Toshifumi Satoh
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Cyclic homopolymers with various topologies
  • Cyclic copolymers with various topologies
  • Synthetic methods
  • Functional characteristics
  • Single chain characteristics
  • Self-assembling characteristics
  • Structures in solution
  • Morphologies in solid state
  • Properties in solution
  • Properties in solid state
  • Potential applications

Published Papers (7 papers)

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Research

17 pages, 2887 KiB  
Article
Micelle Structure Details and Stabilities of Cyclic Block Copolymer Amphiphile and Its Linear Analogues
by Brian J. Ree, Toshifumi Satoh and Takuya Yamamoto
Polymers 2019, 11(1), 163; https://doi.org/10.3390/polym11010163 - 17 Jan 2019
Cited by 14 | Viewed by 6852
Abstract
In this study, we investigate structures and stabilities of the micelles of a cyclic amphiphile (c-PBA-b-PEO) composed of poly(n-butyl acrylate) (PBA) and poly(ethylene oxide) (PEO) blocks and its linear diblock and triblock analogues (l-PBA-b [...] Read more.
In this study, we investigate structures and stabilities of the micelles of a cyclic amphiphile (c-PBA-b-PEO) composed of poly(n-butyl acrylate) (PBA) and poly(ethylene oxide) (PEO) blocks and its linear diblock and triblock analogues (l-PBA-b-PEO and l-PBA-b-PEO-b-PBA) by using synchrotron X-ray scattering and quantitative data analysis. The comprehensive scattering analysis gives details and insights to the micellar architecture through structural parameters. Furthermore, this analysis provides direct clues for structural stabilities in micelles, which can be used as a good guideline to design highly stable micelles. Interestingly, in water, all topological polymers are found to form ellipsoidal micelles rather than spherical micelles; more interestingly, the cyclic polymer and its linear triblock analog make oblate-ellipsoidal micelles while the linear diblock analog makes a prolate-ellipsoidal micelle. The analysis results collectively inform that the cyclic topology enables more compact micelle formation as well as provides a positive impact on the micellar structural integrity. Full article
(This article belongs to the Special Issue Cyclic Polymers)
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20 pages, 2297 KiB  
Article
A Comparative Study of Dynamic Light and X-ray Scatterings on Micelles of Topological Polymer Amphiphiles
by Brian J. Ree, Jongchan Lee, Yusuke Satoh, Kyungho Kwon, Takuya Isono, Toshifumi Satoh and Moonhor Ree
Polymers 2018, 10(12), 1347; https://doi.org/10.3390/polym10121347 - 05 Dec 2018
Cited by 21 | Viewed by 6186
Abstract
Micelles were prepared in organic solvents by using three topological polymer amphiphiles: (i) cyclic poly(n-decyl glycidyl ether-block-2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether) (c-PDGE-b-PTEGGE) and (ii) its linear analogue (l-PDGE-b-PTEGGE); (iii) linear poly(6-phosphorylcholinehexylthiopropyl glycidyl ether- [...] Read more.
Micelles were prepared in organic solvents by using three topological polymer amphiphiles: (i) cyclic poly(n-decyl glycidyl ether-block-2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether) (c-PDGE-b-PTEGGE) and (ii) its linear analogue (l-PDGE-b-PTEGGE); (iii) linear poly(6-phosphorylcholinehexylthiopropyl glycidyl ether-block-n-dodecanoyl glycidyl ether) (l-PPCGE-b-PDDGE). For the individual micelle solutions, the size and distribution were determined by dynamic light scattering (DLS) and synchrotron X-ray scattering analyses. The synchrotron X-ray scattering analysis further found that c-PDGE-b-PTEGGE forms oblate ellipsoidal micelle in an ethanol/water mixture, l-PDGE-b-PTEGGE makes prolate ellipsoidal micelle in an ethanol/water mixture, and l-PPCGE-b-PDDGE forms cylindrical micelle in chloroform. This comparative study found that there are large differences in the size and distribution results extracted by DLS and X-ray scattering analyses. All possible factors to cause such large differences are discussed. Moreover, a better use of the DLS instrument with keeping its merits is proposed. Full article
(This article belongs to the Special Issue Cyclic Polymers)
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13 pages, 3502 KiB  
Article
Synthesis of μ-ABC Tricyclic Miktoarm Star Polymer via Intramolecular Click Cyclization
by Tomoki Shingu, Takuya Yamamoto, Kenji Tajima, Takuya Isono and Toshifumi Satoh
Polymers 2018, 10(8), 877; https://doi.org/10.3390/polym10080877 - 06 Aug 2018
Cited by 6 | Viewed by 4957
Abstract
Cyclic polymers exhibit unique physical and chemical properties because of the restricted chain mobility and absence of chain ends. Although many types of homopolymers and diblock copolymers possessing cyclic architectures have been synthesized to date, there are relatively few reports of cyclic triblock [...] Read more.
Cyclic polymers exhibit unique physical and chemical properties because of the restricted chain mobility and absence of chain ends. Although many types of homopolymers and diblock copolymers possessing cyclic architectures have been synthesized to date, there are relatively few reports of cyclic triblock terpolymers because of their synthetic difficulties. In this study, a novel synthetic approach for μ-ABC tricyclic miktoarm star polymers involving t-Bu-P4-catalyzed ring-opening polymerization (ROP) of glycidyl ethers and intramolecular copper-catalyzed azido-alkyne cycloaddition (CuAAC) was developed. First, the t-Bu-P4-catalyzed ROP of decyl glycidyl ether, dec-9-enyl glycidyl ether, and 2-(2-(2-methoxyethoxy) ethoxy) ethyl glycidyl ether with the aid of functional initiators and terminators was employed for the preparation of a clickable linear triblock terpolymer precursor possessing three azido and three ethynyl groups at the selected positions. Next, the intramolecular CuAAC of the linear precursor successfully produced the well-defined tricyclic triblock terpolymer with narrow dispersity in a reasonable yield. The present strategy is useful for synthesizing model polymers for studying the topological effects on the triblock terpolymer self-assembly. Full article
(This article belongs to the Special Issue Cyclic Polymers)
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10 pages, 2837 KiB  
Article
Identity of Low-Molecular-Weight Species Formed in End-To-End Cyclization Reactions Performed in THF
by Ching W. Pan, Katherine Xia, Samantha A. Parker and Eric S. Tillman
Polymers 2018, 10(8), 844; https://doi.org/10.3390/polym10080844 - 31 Jul 2018
Cited by 4 | Viewed by 4533
Abstract
Cyclic polymers were produced by end-to-end coupling of telechelic linear polymers under dilute conditions in THF, using intramolecular atom transfer radical coupling or click chemistry. In addition to the expected shift to longer elution times on gel permeation chromatography (GPC) indicative of the [...] Read more.
Cyclic polymers were produced by end-to-end coupling of telechelic linear polymers under dilute conditions in THF, using intramolecular atom transfer radical coupling or click chemistry. In addition to the expected shift to longer elution times on gel permeation chromatography (GPC) indicative of the formation of cyclic product, lower molecular weight species were consistently observed upon analysis of the unpurified cyclization reaction mixture. By systematically removing or altering single reaction components in the highly dilute cyclization reaction, it was found that THF itself was responsible for the low-molecular-weight material, forming oligomeric chains of poly(THF) regardless of the other reaction components. When the reactions were performed at higher concentrations and for shorter time intervals, conducive to intermolecular chain-end-joining reactions, the low-molecular-weight peaks were absent. Isolation of the material and analysis by 1H NMR confirmed that poly(THF) was being formed in the highly dilute conditions required for cyclization by end-to-end coupling. When a series of mock cyclization reactions were performed with molar ratios of the reactants held constant, but concentrations changed, it was found that lower concentrations of reactants led to higher amounts of poly(THF) side product. Full article
(This article belongs to the Special Issue Cyclic Polymers)
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9 pages, 2091 KiB  
Article
Organocatalytic Stereoselective Cyclic Polylactide Synthesis in Supercritical Carbon Dioxide under Plasticizing Conditions
by Nobuyuki Mase, Moniruzzaman, Shoji Yamamoto, Yoshitaka Nakaya, Kohei Sato and Tetsuo Narumi
Polymers 2018, 10(7), 713; https://doi.org/10.3390/polym10070713 - 28 Jun 2018
Cited by 17 | Viewed by 3951
Abstract
Cyclic polylactide (cPLA) is a structural isomer of linear polylactide (PLA) although it possesses unique functionalities in comparison to its linear counterpart. Hitherto, the control of stereochemical purity in conventional cPLA synthesis has not been achieved. In this study, highly [...] Read more.
Cyclic polylactide (cPLA) is a structural isomer of linear polylactide (PLA) although it possesses unique functionalities in comparison to its linear counterpart. Hitherto, the control of stereochemical purity in conventional cPLA synthesis has not been achieved. In this study, highly stereochemically pure cPLA was synthesized in the absence of a metal catalyst and organic solvent, which required high consumption of the residual monomer. The synthesis was conducted in supercritical carbon dioxide under CO2 plasticizing polymerization conditions in the presence of an organocatalyst and thiourea additives. In comparison with the stereocomplexes synthesized through conventional methods, cPLA from l-lactide (cPLLA) and cPLA from d-lactide (cPDLA) were synthesized with higher stereochemical purity and improved thermal stability. Moreover, the method presented herein is environmentally friendly and thus, applicable on an industrial level. Full article
(This article belongs to the Special Issue Cyclic Polymers)
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10 pages, 1633 KiB  
Communication
Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization
by Atsushi Narumi, Tetsuya Kobayashi, Masatsugu Yamada, Wolfgang H. Binder, Keigo Matsuda, Montaser Shaykoon Ahmed Shaykoon, Kazushi Enomoto, Moriya Kikuchi and Seigou Kawaguchi
Polymers 2018, 10(6), 638; https://doi.org/10.3390/polym10060638 - 08 Jun 2018
Cited by 6 | Viewed by 5317
Abstract
Macrocyclic polymers present an important class of macromolecules, displaying the reduced radius of gyration or impossibility to entangle. A rare approach for their synthesis is the ring expansion-controlled radical “vinyl” polymerization, starting from a cyclic alkoxyamine. We here describe ring-expansion radical crossover reactions [...] Read more.
Macrocyclic polymers present an important class of macromolecules, displaying the reduced radius of gyration or impossibility to entangle. A rare approach for their synthesis is the ring expansion-controlled radical “vinyl” polymerization, starting from a cyclic alkoxyamine. We here describe ring-expansion radical crossover reactions of cyclic alkoxyamines which run in parallel to chain-propagation reactions in the polymerization system. The radical crossover reactions extensively occurred at 105–125 °C, eventually producing high molecular weight polymers with multiple inherent dynamic covalent bonds (NOC bonds). A subsequent ring-contraction radical crossover reaction and the second ring-expansion radical crossover reaction are also described. The major products for the respective three stages were shown to possess cyclic morphologies by the molecular weight profiles and the residual ratios for the NOC bonds (φ in %). In particular, the high φ values ranging from ca. 80% to 98% were achieved for this cyclic alkoxyamine system. This result verifies the high availability of this system as a tool demonstrating the ring-expansion “vinyl” polymerization that allows them to produce macrocyclic polymers via a one-step vinyl polymerization. Full article
(This article belongs to the Special Issue Cyclic Polymers)
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29 pages, 3762 KiB  
Article
Precise Synthesis, Properties, and Structures of Cyclic Poly(ε-caprolactone)s
by Li Xiang, Wonyeong Ryu, Heesoo Kim and Moonhor Ree
Polymers 2018, 10(6), 577; https://doi.org/10.3390/polym10060577 - 23 May 2018
Cited by 23 | Viewed by 4979
Abstract
Cyclic PCL (c-PCL) has drawn great attention from academia and industry because of its unique, unusual structure and property characteristics due to the absence of end groups in addition to the biocompatibility and biodegradability of its linear analogue. As a result [...] Read more.
Cyclic PCL (c-PCL) has drawn great attention from academia and industry because of its unique, unusual structure and property characteristics due to the absence of end groups in addition to the biocompatibility and biodegradability of its linear analogue. As a result of much research effort, several synthetic methods have been developed to produce c-PCLs so far. Their chain, morphology and property characteristics were investigated even though carried out on a very limited basis. This feature article reviews the research progress made in the synthesis, morphology, and properties of c-PCL; all results and their pros and cons are discussed in terms of purity and molecular weight distribution in addition to the cyclic topology effect. In addition, we attempted to synthesize a series of c-PCL products of high purity by using intramolecular azido-alkynyl click cyclization chemistry and subsequent precise and controlled separation and purification; and their thermal degradation and phase transitions were investigated in terms of the cyclic topology effect. Full article
(This article belongs to the Special Issue Cyclic Polymers)
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