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Special Issue "Ring-Opening Polymerization"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Synthesis".

Deadline for manuscript submissions: closed (28 February 2015)

Special Issue Editors

Guest Editor
Prof. Dr. Atsushi Sudo

Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, Kowakae 3-4-1, Higashi-Osaka, Osaka 577-8502, Japan
Website | E-Mail
Interests: bio-based polymers; Networked polymers; High-performance materials
Guest Editor
Prof. Dr. Takeshi Endo

Molecular Engineering Institute, Kinki University, 11-6 Kayanomori, Iizuka, Fukuoka 820-8555, Japan
Website | E-Mail
Interests: polymer synthesis; ring-opening polymerization; equilibrium polymerization; networked polymers

Special Issue Information

Dear Colleagues,

Ring-opening polymerization gives us access to various heteroatom-containing polymers with unique properties and functions that are rather difficult to obtain by chain polymerization of vinyl monomers. To date, a wide variety of cyclic monomers have been developed and their efficient ring-opening polymerizations, both ionic ones and radical ones, have been achieved. In addition, recent advance in living/controlled ring-opening polymerizations has enabled us to develop powerful tools for synthesizing well-defined polymers with controlled chain length and terminus, as well as those for constructing various polymer architectures such as block copolymers, graft copolymers, and star-shaped polymers that exhibit intriguing self-assemblies and the consequent micellization and phase separation behaviors. The advantages of ring-opening polymerizations are opening new doors for their applications in the fields of pharmaceutics, biomaterials, electronics, and aerospace materials.

We invite our colleagues to submit research articles and comprehensive reviews addressing the above-mentioned topics, and on recent advances in ring-opening polymerization in general, for publication in this Special Issue.

Prof. Dr. Atsushi Sudo
Prof. Dr. Takeshi Endo
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 papers will be 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. Molecules is an international peer-reviewed open access monthly 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 1800 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

  • new cyclic monomers
  • ionic ring-opening polymerization
  • radical ring-opening polymerization
  • living/controlled ring-opening polymerization
  • polymer architectures
  • polymer properties
  • morphology
  • degradability

Published Papers (12 papers)

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Editorial

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Open AccessEditorial Special Issue “Ring-Opening Polymerization”
Molecules 2016, 21(12), 1720; doi:10.3390/molecules21121720
Received: 5 December 2016 / Revised: 8 December 2016 / Accepted: 8 December 2016 / Published: 14 December 2016
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(This article belongs to the Special Issue Ring-Opening Polymerization)

Research

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Open AccessArticle One-Pot Synthesis of Organic-Sulfur-Zinc Hybrid Materials via Polycondensation of a Zinc Salt and Thiols Generated in Situ from Cyclic Dithiocarbonates
Molecules 2015, 20(8), 15049-15059; doi:10.3390/molecules200815049
Received: 12 May 2015 / Revised: 12 May 2015 / Accepted: 10 August 2015 / Published: 17 August 2015
Cited by 2 | PDF Full-text (1137 KB) | HTML Full-text | XML Full-text
Abstract
Soluble organic-sulfur-zinc hybrid polymers were prepared via a one-pot reaction consisting of ring-opening addition and subsequent polycondensation. The first reaction is the nucleophilic ring-opening addition of 2-ethylhexylamine to multifunctional cyclic dithiocarbonates giving multiple thiols in situ. The sequential polycondensation of the in
[...] Read more.
Soluble organic-sulfur-zinc hybrid polymers were prepared via a one-pot reaction consisting of ring-opening addition and subsequent polycondensation. The first reaction is the nucleophilic ring-opening addition of 2-ethylhexylamine to multifunctional cyclic dithiocarbonates giving multiple thiols in situ. The sequential polycondensation of the in situ generated thiols with Zn(OAc)2 gave the target hybrid polymers. This one-pot method enabled the use of a shorter amine than the previous polycondensation of Zn(OAc)2 and purified thiols, which required octadecylamine to obtain a soluble product. The obtained hybrid polymers may be cast as composite films with polystyrene and poly(methyl methacrylate). Owing to the shorter alkyl chain, the calculated nD values of the products (1.60 or 1.61) are higher than that of the previous product bearing octadecyl chains (1.53). Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
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Open AccessArticle Green Polymer Chemistry: Investigating the Mechanism of Radical Ring-Opening Redox Polymerization (R3P) of 3,6-Dioxa-1,8-octanedithiol (DODT)
Molecules 2015, 20(4), 6504-6519; doi:10.3390/molecules20046504
Received: 28 February 2015 / Revised: 1 April 2015 / Accepted: 7 April 2015 / Published: 13 April 2015
Cited by 2 | PDF Full-text (1556 KB) | HTML Full-text | XML Full-text
Abstract
The mechanism of the new Radical Ring-opening Redox Polymerization (R3P) of 3,6-dioxa-1,8-octanedithiol (DODT) by triethylamine (TEA) and dilute H2O2 was investigated. Scouting studies showed that the formation of high molecular weight polymers required a 1:2 molar ratio of
[...] Read more.
The mechanism of the new Radical Ring-opening Redox Polymerization (R3P) of 3,6-dioxa-1,8-octanedithiol (DODT) by triethylamine (TEA) and dilute H2O2 was investigated. Scouting studies showed that the formation of high molecular weight polymers required a 1:2 molar ratio of DODT to TEA and of DODT to H2O2. Further investigation into the chemical composition of the organic and aqueous phases by 1H-NMR spectroscopy and mass spectrometry demonstrated that DODT is ionized by two TEA molecules (one for each thiol group) and thus transferred into the aqueous phase. The organic phase was found to have cyclic disulfide dimers, trimers and tetramers. Dissolving DODT and TEA in water before the addition of H2O2 yielded a polymer with Mn = 55,000 g/mol, in comparison with Mn = 92,000 g/mol when aqueous H2O2 was added to a DODT/TEA mixture. After polymer removal, MALDI-ToF MS analysis of the residual reaction mixtures showed only cyclic oligomers remaining. Below the LCST for TEA in water, 18.7 °C, the system yielded a stable emulsion, and only cyclic oligomers were found. Below DODT/TEA and H2O2 1:2 molar ratio mostly linear oligomers were formed, with <20% cyclic oligomers. The findings support the proposed mechanism of R3P. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
Open AccessArticle Copolymers of Vinyl-Containing Benzoxazine with Vinyl Monomers as Precursors for High Performance Thermosets
Molecules 2015, 20(4), 6488-6503; doi:10.3390/molecules20046488
Received: 27 February 2015 / Revised: 27 March 2015 / Accepted: 7 April 2015 / Published: 10 April 2015
Cited by 7 | PDF Full-text (1914 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A benzoxazine containing a vinyl group (P-4va) was prepared by the reaction of phenol, 4-vinylaniline, and paraformaldehyde. A differential scanning calorimetry (DSC) study revealed that ring-opening polymerization of the benzoxazine and chain polymerization of the vinyl group occurred in the same temperature range.
[...] Read more.
A benzoxazine containing a vinyl group (P-4va) was prepared by the reaction of phenol, 4-vinylaniline, and paraformaldehyde. A differential scanning calorimetry (DSC) study revealed that ring-opening polymerization of the benzoxazine and chain polymerization of the vinyl group occurred in the same temperature range. When 2,2'-azobisisobutyronitrile was added as a radical initiator to P-4va, however, only the vinyl groups were polymerized at lower temperature, giving oligo(P-4va) that contains pendent benzoxazine units. Radical copolymerization of P-4va with various vinyl monomers such as styrene, methyl methacrylate (MMA), and n-butyl acrylate (BuA) was examined. The chemical structure of the copolymers was confirmed by FT-IR and 1H-NMR to be one of polyolefins bearing benzoxazine units as the pendant groups. The weight-average molecular weights of the copolymers determined by size exclusion chromatography were to be in the range of 1900–51,500 depending on the comonomers. DSC of the copolymers showed that the maxima of the exothermic peaks corresponding to the ring-opening polymerization of the pendent benzoxazine units were observed in the temperature range of 229–250 °C. Thermal cure up to 240 °C of the copolymer films afforded homogenous transparent films with improved thermal properties. Tough cured film was obtained by the copolymerization with MMA, while a tough and flexible film was obtained by the copolymerization with BuA. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
Open AccessArticle Ring-Opening Graft Polymerization of Propylene Carbonate onto Xylan in an Ionic Liquid
Molecules 2015, 20(4), 6033-6047; doi:10.3390/molecules20046033
Received: 27 February 2015 / Revised: 25 March 2015 / Accepted: 2 April 2015 / Published: 7 April 2015
Cited by 11 | PDF Full-text (2210 KB) | HTML Full-text | XML Full-text
Abstract
The amidine organocatalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is an effective nucleophilic catalyst. Biocomposites with tuneable properties were successfully synthesized by ring-opening graft polymerization (ROGP) of propylene carbonate (PC) onto xylan using DBU as a catalyst in the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The effects
[...] Read more.
The amidine organocatalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is an effective nucleophilic catalyst. Biocomposites with tuneable properties were successfully synthesized by ring-opening graft polymerization (ROGP) of propylene carbonate (PC) onto xylan using DBU as a catalyst in the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The effects of reaction temperature, reaction time and the molar ratio of PC to anhydroxylose units (AXU) in xylan were investigated. The physico-chemical properties of xylan-graft-poly(propylene carbonate) (xylan-g-PPC) copolymers were characterised by FT-IR, NMR, TGA/DTG, AFM and tensile analysis. The FT-IR and NMR results indicated the successful attachment of PPC onto xylan. TGA/DTG suggested the increased thermal stability of xylan after the attachment of PPC side chains. AFM analysis revealed details about the molecular aggregation of xylan-g-PPC films. The results also showed that with the increased DS of xylan-g-PPC copolymers, the tensile strength and Young’s modulus of the films decreased, while the elongation at break increased. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
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Open AccessArticle Zinc Complexes Containing Coumarin-Derived Anilido-Aldimine Ligands as Catalysts for Ring Opening Polymerization of L-Lactide
Molecules 2015, 20(4), 5313-5328; doi:10.3390/molecules20045313
Received: 12 February 2015 / Revised: 13 March 2015 / Accepted: 20 March 2015 / Published: 24 March 2015
Cited by 5 | PDF Full-text (2855 KB) | HTML Full-text | XML Full-text
Abstract
The coumarin-derived ligand precursors L1HL6H have been prepared. Treatment of these ligand precursors with 1.2 equiv. of ZnEt2 in toluene affords zinc ethyl complexes (LZnEt) 16 (where L = coumarin-derived ligands bearing different functional
[...] Read more.
The coumarin-derived ligand precursors L1HL6H have been prepared. Treatment of these ligand precursors with 1.2 equiv. of ZnEt2 in toluene affords zinc ethyl complexes (LZnEt) 16 (where L = coumarin-derived ligands bearing different functional groups). Reaction of ligand precursor L3H with 1.5 equiv. of Zn[N(SiMe3)2]2 in toluene affords the zinc amide complex, L3ZnN(SiMe3)2, 7. All these compounds were characterized by NMR spectroscopy and elemental analysis. The molecular structures are reported for 1 and 7. The catalytic activities of complexes 17 towards the ring opening polymerization of l-lactide in the presence of 9-AnOH have been investigated. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
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Open AccessArticle Cyclic Comonomers for the Synthesis of Carboxylic Acid and Amine Functionalized Poly(l-Lactic Acid)
Molecules 2015, 20(3), 4764-4779; doi:10.3390/molecules20034764
Received: 15 January 2015 / Revised: 23 February 2015 / Accepted: 2 March 2015 / Published: 16 March 2015
Cited by 4 | PDF Full-text (694 KB) | HTML Full-text | XML Full-text
Abstract
Degradable aliphatic polyesters such as poly(lactic acid) are widely used in biomedical applications, however, they lack functional moieties along the polymer backbone that are amenable for functionalization reactions or could be the basis for interactions with biological systems. Here we present a straightforward
[...] Read more.
Degradable aliphatic polyesters such as poly(lactic acid) are widely used in biomedical applications, however, they lack functional moieties along the polymer backbone that are amenable for functionalization reactions or could be the basis for interactions with biological systems. Here we present a straightforward route for the synthesis of functional α-ω epoxyesters as comonomers for lactide polymerization. Salient features of these highly functionalized epoxides are versatility in functionality and a short synthetic route of less than four steps. The α-ω epoxyesters presented serve as a means to introduce carboxylic acid and amine functional groups into poly(lactic acid) polymers via ring-opening copolymerization. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
Figures

Open AccessArticle Ring-Opening Polymerization of ε-Caprolactone Initiated by Ganciclovir (GCV) for the Preparation of GCV-Tagged Polymeric Micelles
Molecules 2015, 20(2), 2857-2867; doi:10.3390/molecules20022857
Received: 13 December 2014 / Accepted: 3 February 2015 / Published: 10 February 2015
Cited by 3 | PDF Full-text (1151 KB) | HTML Full-text | XML Full-text
Abstract
Ganciclovir (GCV) is a nucleoside analogue with antiviral activity against herpes viral infections, and the most widely used antiviral to treat cytomegalovirus infections. However, the low bioavailability and short half-life of GCV necessitate the development of a carrier for sustained delivery. In this
[...] Read more.
Ganciclovir (GCV) is a nucleoside analogue with antiviral activity against herpes viral infections, and the most widely used antiviral to treat cytomegalovirus infections. However, the low bioavailability and short half-life of GCV necessitate the development of a carrier for sustained delivery. In this study, guanosine-based GCV was used as the initiator directly in ring-opening polymerization of ε-caprolactone (ε-CL) to form hydrophobic GCV-poly(caprolactone) (GCV-PCL) which was then grafted with hydrophilic chitosan to form amphiphilic copolymers for the preparation of stable micellar nanoparticles. Successful synthesis of GCV-PCL and GCV-PCL-chitosan were verified by 1H-NMR analysis. Self-assembled micellar nanoparticles were characterized by dynamic light scattering and zetasizer with an average size of 117 nm and a positive charge of 24.2 mV. The drug release kinetics of GCV was investigated and cytotoxicity assay demonstrated that GCV-tagged polymeric micelles were non-toxic. Our results showed that GCV could be used directly in the initiation of ring-opening polymerization of ε-CL and non-toxic polymeric micelles for GCV delivery can be formed. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
Open AccessCommunication Novel Zinc-Catalytic Systems for Ring-Opening Polymerization of ε-Caprolactone
Molecules 2015, 20(2), 2816-2827; doi:10.3390/molecules20022816
Received: 17 December 2014 / Accepted: 3 January 2015 / Published: 9 February 2015
Cited by 7 | PDF Full-text (995 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Polycaprolactone (PCL) is a biodegradable synthetic polymer that is currently widely used in many pharmaceutical and medical applications. In this paper we describe the coordination ring-opening polymerization of ε-caprolactone in the presence of two newly synthesized catalytic systems: diethylzinc/gallic acid and diethylzinc/propyl gallate.
[...] Read more.
Polycaprolactone (PCL) is a biodegradable synthetic polymer that is currently widely used in many pharmaceutical and medical applications. In this paper we describe the coordination ring-opening polymerization of ε-caprolactone in the presence of two newly synthesized catalytic systems: diethylzinc/gallic acid and diethylzinc/propyl gallate. The chemical structures of the obtained PCLs were characterized by 1H- or 13C-NMR, FTIR spectroscopy and MALDI TOF mass spectrometry. The average molecular weight of the resulting polyesters was analysed by gel permeation chromatography and a viscosity method. The effects of temperature, reaction time and type of catalytic system on the polymerization process were examined. Linear PCLs with defined average molecular weight were successfully obtained. Importantly, in some cases the presence of macrocyclic products was not observed during the polymerization process. This study provides an effective method for the synthesis of biodegradable polyesters for medical and pharmaceutical applications due to the fact that gallic acid/propyl gallate are commonly used in the pharmaceutical industry. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
Open AccessArticle Post-Polymerization Modification of Poly(L-glutamic acid) with D-(+)-Glucosamine
Molecules 2014, 19(12), 19751-19768; doi:10.3390/molecules191219751
Received: 30 October 2014 / Revised: 20 November 2014 / Accepted: 24 November 2014 / Published: 27 November 2014
Cited by 6 | PDF Full-text (2918 KB) | HTML Full-text | XML Full-text
Abstract
Carboxyl functional groups of poly(L-glutamic acid) (PGlu) were modified with a D-(+)-glucosamine (GlcN) by amidation using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) as a coupling reagent. The coupling reaction was performed in aqueous medium without protection of hydroxyl functional groups of D-(+)-glucosamine. Poly(L-glutamic acid) and GlcN
[...] Read more.
Carboxyl functional groups of poly(L-glutamic acid) (PGlu) were modified with a D-(+)-glucosamine (GlcN) by amidation using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) as a coupling reagent. The coupling reaction was performed in aqueous medium without protection of hydroxyl functional groups of D-(+)-glucosamine. Poly(L-glutamic acid) and GlcN functionalized polyglutamates (P(Glu-GlcN)) were thoroughly characterized by 1D and 2D NMR spectroscopy and SEC-MALS to gain detailed information on their structure, composition and molar mass characteristics. The results reveal successful functionalization with GlcN through the amide bond and also to a minor extent through ester bond formation in position 1 of GlcN. In addition, a ratio between the α- and β-form of glucosamine substituent coupled to polyglutamate repeating units as well as the content of residual dimethoxy triazinyl active ester moiety in the samples were evaluated. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
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Review

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Open AccessReview Recent Developments of Versatile Photoinitiating Systems for Cationic Ring Opening Polymerization Operating at Any Wavelengths and under Low Light Intensity Sources
Molecules 2015, 20(4), 7201-7221; doi:10.3390/molecules20047201
Received: 25 February 2015 / Revised: 27 March 2015 / Accepted: 30 March 2015 / Published: 20 April 2015
Cited by 17 | PDF Full-text (2276 KB) | HTML Full-text | XML Full-text
Abstract
Photoinitiators (PI) or photoinitiating systems (PIS) usable in light induced cationic polymerization (CP) and free radical promoted cationic polymerization (FRPCP) reactions (more specifically for cationic ring opening polymerization (ROP)) together with the involved mechanisms are briefly reviewed. The recent developments of novel two-
[...] Read more.
Photoinitiators (PI) or photoinitiating systems (PIS) usable in light induced cationic polymerization (CP) and free radical promoted cationic polymerization (FRPCP) reactions (more specifically for cationic ring opening polymerization (ROP)) together with the involved mechanisms are briefly reviewed. The recent developments of novel two- and three-component PISs for CP and FRPCP upon exposure to low intensity blue to red lights is emphasized in details. Examples of such reactions under various experimental conditions are provided. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
Open AccessReview Enzymatic Polymerization of Cyclic Monomers in Ionic Liquids as a Prospective Synthesis Method for Polyesters Used in Drug Delivery Systems
Molecules 2015, 20(1), 1-23; doi:10.3390/molecules20010001
Received: 15 October 2014 / Accepted: 16 December 2014 / Published: 23 December 2014
Cited by 12 | PDF Full-text (752 KB) | HTML Full-text | XML Full-text
Abstract
Biodegradable or bioresorbable polymers are commonly used in various pharmaceutical fields (e.g., as drug delivery systems, therapeutic systems or macromolecular drug conjugates). Polyesters are an important class of polymers widely utilized in pharmacy due to their biodegradability and biocompatibility features. In recent years,
[...] Read more.
Biodegradable or bioresorbable polymers are commonly used in various pharmaceutical fields (e.g., as drug delivery systems, therapeutic systems or macromolecular drug conjugates). Polyesters are an important class of polymers widely utilized in pharmacy due to their biodegradability and biocompatibility features. In recent years, there has been increased interest in enzyme-catalyzed ring-opening polymerization (e-ROP) of cyclic esters as an alternative method of preparation of biodegradable or bioresorbable polymers. Ionic liquids (ILs) have been presented as green solvents in enzymatic ring-opening polymerization. The activity, stability, selectivity of enzymes in ILs and the ability to catalyze polyester synthesis under these conditions are discussed. Overall, the review demonstrates that e-ROP of lactones or lactides could be an effective method for the synthesis of useful biomedical polymers. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
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