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Polymers
Special Issues
Precision Polymer Synthesis
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Precision Polymer Synthesis

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

Deadline for manuscript submissions: closed (30 April 2015)

Special Issue Editor

Prof. Dr. Tanja Junkers

E-Mail Website
Guest Editor
School of Chemistry, Monash University, Clayton VIC 3800, Australia
Interests: controlled radical polymerization; polymerization kinetics; polymer conjugation; radical spin traps; novel polymerization protocols; mass spectrometry of polymers; microreactor applications

Special Issue Information

Dear Colleagues,

The advent of controlled polymerization techniques in the last few decades has truly revolutionized synthetic polymer chemistry. With the contemporary toolbox of synthetic methods at hand, a large variety of materials can be accessed and the frontier in research has been shifted from the pure design of complex macromolecular structures towards materials with biological precision. Macromolecules can contain encoded information via sequence control (e.g., sequences of small polydisperse segments of true monomer sequences) or can exert complex behaviors, such as chain folding, the formation of tertiary structures or generally, the formation of complex single-chain nanoparticles. Development of such materials requires highly precise methods in synthesis, in-depth studies on the physical properties of the macromolecules, and high-level characterization of products.  Even though precise polymer synthesis is still a young field of exploration, developments are fast and new generations of synthetic materials are rapidly evolving and are becoming closer and closer in structure, shape, and function to biomacromolecules.

This Special Issue focuses on the latest achievements in the field of precision polymer synthesis with respect to the development of polymeric materials that match or advance biological precision and function. Therefore, we will highlight topics concerning the synthesis of complex polymers, their physical properties, their ability to fold and arrange themselves, and the characterization of such materials with state-of-the-art methodologies.

Prof. Dr. Thomas Junkers
Guest Editor

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

  • sequence control
  • controlled polymerization
  • multiblock copolymers
  • single-molecule nanoparticles
  • chain folding

Published Papers (5 papers)

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Research

5039 KiB  
Article
The Effect of Allylic Sulfide-Mediated IrreversibleAddition-Fragment Chain Transfer on the EmulsionPolymerization Kinetics of Styrene
by Li An, Zhihui Di, Biaobiao Yu, Jialing Pu and Zhongxiao Li
Polymers 2015, 7(10), 1918-1938; https://doi.org/10.3390/polym7101490 - 29 Sep 2015
Cited by 4 | Viewed by 7478
Abstract
The effect of the irreversible addition-fragment chain transfer agent, butyl(2-phenylallyl)sulfane (BPAS), on the course of the emulsion polymerization of styrene and on the product molecular weight was investigated. The emulsion polymerizations were performed using various amounts of sodium dodecyl sulfate (SDS) as the [...] Read more.
The effect of the irreversible addition-fragment chain transfer agent, butyl(2-phenylallyl)sulfane (BPAS), on the course of the emulsion polymerization of styrene and on the product molecular weight was investigated. The emulsion polymerizations were performed using various amounts of sodium dodecyl sulfate (SDS) as the surfactant and potassium peroxodisulfate (KPS) as the initiator. The relationships between the rates of polymerization (\(R_{p} \)) and the number of particles per volume (\(N_{c} \)) with respect to the concentrations of KPS, SDS, and BPAS were found to be \(R_{p} \propto \left\lbrack KPS \right\rbrack^{0.29} \), \(N_{c} \propto \left\lbrack KPS \right\rbrack^{0.26} \),\(R_{p} \propto \left\lbrack SDS \right\rbrack^{0.68} \), \(N_{c} \propto \left\lbrack SDS \right\rbrack^{0.72} \), and \(R_{p} \propto \left\lbrack BPAS \right\rbrack^{- 0.73} \) . The obtained relationships can be attributed to the exit of the leaving group radicals on BPAS from the polymer particles. The experimental values of the average number of radicals per particle (\(\overset{\_}{n} \)) were strongly dependent on the BPAS concentration and were in good agreement with the theoretical values (\({\overset{\_}{n}}_{theo} \)) from model calculations. The number-average molecular weight (\(\overset{\_}{M_{n}} \)) can be controlled by BPAS over nearly the entire conversion range, which is also in agreement with the mathematical model. In addition, the transfer rate coefficient (\(k_{tr} \)) of BPAS can be estimated as 326 L/mol/s at 70 \(^\circ\)C. Moreover, similar good results were found for the tested redox reactions at 30 \(^\circ\)C. Full article
(This article belongs to the Special Issue Precision Polymer Synthesis)
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2767 KiB  
Article
Synthesis of Hyperbranched Poly(ε-caprolactone) Containing Terminal Azobenzene Structure via Combined Ring-Opening Polymerization and “Click” Chemistry
by Xiaoqiang Xue, Jing Yang, Wenyan Huang, Hongjun Yang and Bibiao Jiang
Polymers 2015, 7(7), 1248-1268; https://doi.org/10.3390/polym7071248 - 09 Jul 2015
Cited by 18 | Viewed by 8677
Abstract
A novel well-defined linear poly(ε-caprolactone) (P1) containing terminal azobenzene and ethyne groups was successfully synthesized through tin-catalyzed ring-opening polymerization of ε-caprolactone in the presence of N,N′-bis(2-hydroxyethyl)-4-(3-ethynylphenylazo)aniline (BHA) in bulk. Subsequent reactions allowed the synthesis of the corresponding bromoester end-functionalized polymer [...] Read more.
A novel well-defined linear poly(ε-caprolactone) (P1) containing terminal azobenzene and ethyne groups was successfully synthesized through tin-catalyzed ring-opening polymerization of ε-caprolactone in the presence of N,N′-bis(2-hydroxyethyl)-4-(3-ethynylphenylazo)aniline (BHA) in bulk. Subsequent reactions allowed the synthesis of the corresponding bromoester end-functionalized polymer (P2), which was converted into AB2 type polymer (P3) containing terminal azide groups with NaN3. Consequently, hyperbranched poly(ε-caprolactone) (HPCL) was prepared with AB2 macromonomer (P3) by “click” chemistry under the catalysis of CuSO4·5H2O/sodium ascorbate/H2O. The structure of the resultant HPCL was characterized by gel permeation chromatography (GPC), proton nuclear magnetic resonance (1H-NMR), ultraviolet-visible (UV-Vis) spectroscopy and fourier transform infrared spectroscopy (FT-IR). Thermal and crystallization properties of P1 and HPCL were further studied by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and polarised optical microscopy (POM). These results indicated that the crystallinity of HPCL was slightly lower than that of P1 due to the hyperbranched structure of HPCL. Additionally, the photo-induced trans-cis isomerization behaviors of BHA, P1 and HPCL containing terminal azobenzene were investigated in chloroform solution, and the photoisomerization rate constant (kexp) of small molecule (BHA) was nearly three times faster than that of polymers P1 and HPCL, which was due to the sterically hindering effect of the polymer-chain configuration. Full article
(This article belongs to the Special Issue Precision Polymer Synthesis)
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1567 KiB  
Article
Modeling the Influence of Diffusion-Controlled Reactions and Residual Termination and Deactivation on the Rate and Control of Bulk ATRP at High Conversions
by Ali Mohammad Rabea and Shiping Zhu
Polymers 2015, 7(5), 819-835; https://doi.org/10.3390/polym7050819 - 28 Apr 2015
Cited by 35 | Viewed by 7573
Abstract
In high-conversion atom transfer radical polymerization (ATRP), all the reactions, such as radical termination, radical deactivation, dormant chain activation, monomer propagation, etc. could become diffusion controlled sooner or later, depending on relative diffusivities of the involved reacting species. These diffusion-controlled reactions directly affect [...] Read more.
In high-conversion atom transfer radical polymerization (ATRP), all the reactions, such as radical termination, radical deactivation, dormant chain activation, monomer propagation, etc. could become diffusion controlled sooner or later, depending on relative diffusivities of the involved reacting species. These diffusion-controlled reactions directly affect the rate of polymerization and the control of polymer molecular weight. A model is developed to investigate the influence of diffusion-controlled reactions on the high conversion ATRP kinetics. Model simulation reveals that diffusion-controlled termination slightly increases the rate, but it is the diffusion-controlled deactivation that causes auto-acceleration in the rate (“gel effect”) and loss of control. At high conversions, radical chains are “trapped” because of high molecular weight. However, radical centers can still migrate through (1) radical deactivation–activation cycles and (2) monomer propagation, which introduce “residual termination” reactions. It is found that the “residual termination” does not have much influence on the polymerization kinetics. The migration of radical centers through propagation can however facilitate catalytic deactivation of radicals, which improves the control of polymer molecular weight to some extent. Dormant chain activation and monomer propagation also become diffusion controlled and finally stop the polymerization when the system approaches its glass state. Full article
(This article belongs to the Special Issue Precision Polymer Synthesis)
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8764 KiB  
Article
Synthesis of Bio-Based Poly(lactic acid-co-10-hydroxy decanoate) Copolymers with High Thermal Stability and Ductility
by Dongjian Shi, Jinting Hua, Li Zhang and Mingqing Chen
Polymers 2015, 7(3), 468-483; https://doi.org/10.3390/polym7030468 - 05 Mar 2015
Cited by 17 | Viewed by 10942
Abstract
Novel bio-based aliphatic copolyesters, poly(lactic acid-co-10-hydroxy decanoate) (P(LA-co-HDA), PLH), were successfully synthesized from lactic acid (LA) and 10-hydroxycapric acid (HDA) by a thermal polycondensation process, in the presence of p-toluenesulfonic acid (p-TSA) and SnCl2·2H [...] Read more.
Novel bio-based aliphatic copolyesters, poly(lactic acid-co-10-hydroxy decanoate) (P(LA-co-HDA), PLH), were successfully synthesized from lactic acid (LA) and 10-hydroxycapric acid (HDA) by a thermal polycondensation process, in the presence of p-toluenesulfonic acid (p-TSA) and SnCl2·2H2O as co-catalyst. The copolymer structure was characterized by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR). The weight average molecular weights (Mw) of PLH, from gel permeation chromatography (GPC) measurements, were controlled from 18,500 to 37,900 by changing the molar ratios of LA and HDA. Thermogravimetric analysis (TGA) results showed that PLH had excellent thermal stability, and the decomposition temperature at the maximum rate was above 280 °C. The glass transition temperature (Tg) and melting temperature (Tm) of PLH decreased continuously with increasing the HDA composition by differential scanning calorimetry (DSC) measurements. PLH showed high ductility, and the breaking elongation increased significantly by the increment of the HDA composition. Moreover, the PLH copolymer could degrade in buffer solution. The cell adhesion results showed that PLH had good biocompatibility with NIH/3T3 cells. The bio-based PLH copolymers have potential applications as thermoplastics, elastomers or impact modifiers in the biomedical, industrial and agricultural fields. Full article
(This article belongs to the Special Issue Precision Polymer Synthesis)
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0 pages, 654 KiB  
Article
Facile Synthesis of Well-Defined MDMO-PPV Containing (Tri)Block—Copolymers via Controlled Radical Polymerization and CuAAC Conjugation
by Neomy Zaquen, Joke Vandenbergh, Maria Schneider-Baumann, Laurence Lutsen, Dirk Vanderzande and Tanja Junkers
Polymers 2015, 7(3), 418-452; https://doi.org/10.3390/polym7030418 - 24 Feb 2015
Cited by 14 | Viewed by 12864
Abstract
A systematic investigation into the chain transfer polymerization of the so-called radical precursor polymerization of poly(p-phenylene vinylene) (PPV) materials is presented. Polymerizations are characterized by systematic variation of chain transfer agent (CTA) concentration and reaction temperature. For the chain transfer constant, [...] Read more.
A systematic investigation into the chain transfer polymerization of the so-called radical precursor polymerization of poly(p-phenylene vinylene) (PPV) materials is presented. Polymerizations are characterized by systematic variation of chain transfer agent (CTA) concentration and reaction temperature. For the chain transfer constant, a negative activation energy of −12.8 kJ·mol−1 was deduced. Good control over molecular weight is achieved for both the sulfinyl and the dithiocarbamate route (DTC). PPVs with molecular weights ranging from thousands to ten thousands g·mol−1 were obtained. To allow for a meaningful analysis of the CTA influence, Mark–Houwink–Kuhn–Sakurada (MHKS) parameters were determined for conjugated MDMO-PPV ([2-methoxy-5-(3',7'-dimethyloctyloxy)]-1,4-phenylenevinylene) to α = 0.809 and k = 0.00002 mL·g−1. Further, high-endgroup fidelity of the CBr4-derived PPVs was proven via chain extension experiments. MDMO-PPV-Br was successfully used as macroinitiator in atom transfer radical polymerization (ATRP) with acrylates and styrene. A more polar PPV counterpart was chain extended by an acrylate in single-electron transfer living radical polymerization (SET-LRP). In a last step, copper-catalyzed azide alkyne cycloaddition (CuAAC) was used to synthesize block copolymer structures. Direct azidation followed by macromolecular conjugation showed only partial success, while the successive chain extension via ATRP followed by CuAAC afforded triblock copolymers of the poly(p-phenylene vinylene)-block-poly(tert-butyl acrylate)-block-poly(ethylene glycol) (PPV-b-PtBuA-b-PEG). Full article
(This article belongs to the Special Issue Precision Polymer Synthesis)
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