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Polymers, Volume 5, Issue 3 (September 2013), Pages 873-1168

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Editorial

Jump to: Research, Review

Open AccessEditorial Open Access Makes an Impact
Polymers 2013, 5(3), 954-955; doi:10.3390/polym5030954
Received: 2 July 2013 / Accepted: 2 July 2013 / Published: 5 July 2013
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Abstract
Polymers published its first issue in December 2009. At that time, the editorial board and publisher were determined to lead the journal to become another MDPI success story, proving that open access publishing and high quality publications, ensured by a rigorous peer-review [...] Read more.
Polymers published its first issue in December 2009. At that time, the editorial board and publisher were determined to lead the journal to become another MDPI success story, proving that open access publishing and high quality publications, ensured by a rigorous peer-review procedure, followed by fast publication of accepted manuscripts can be achieved. Three and a half years later, after more than 153,000 article downloads in 2012, the journal received its first impact factor (2012 JCR IF: 1.687). Today, Polymers is proud to be the number one open access journal in the category of “Polymer Science”. In order to achieve this, we relied on an editorial board with well-known members from the polymer community, a professional staff and a vision that there is room alongside the established “high impact” journals for publishing science. Recently, the editor in chief of Science, Bruce Alberts, wrote an editorial [1] in favor of the San Francisco Declaration on Research Assessment (DORA), which states that the impact factor must not be used as “a surrogate measure of the quality of individual research articles [2]”. Even though the impact factor certainly is so far the best available measure of the quality of a journal and its impact on the scientific community, when it comes to the single manuscripts published, “there is still no other way to evaluate the quality of scientific papers, but to read them [3]”. Therefore, Polymers celebrates its first impact factor with an appropriate critical distance towards bibliometric data and feels encouraged to continue on the chosen path. With this in mind, I encourage you, our readers, to continuously evaluate the scientific quality of the articles published in Polymers by reading, discussing and citing them. [...] Full article

Research

Jump to: Editorial, Review

Open AccessArticle Extensional Flow Properties of Externally Plasticized Cellulose Acetate: Influence of Plasticizer Content
Polymers 2013, 5(3), 873-889; doi:10.3390/polym5030873
Received: 7 June 2013 / Accepted: 24 June 2013 / Published: 2 July 2013
Cited by 7 | PDF Full-text (3166 KB) | HTML Full-text | XML Full-text
Abstract
Elongational flow properties of polymer melts are very important for numerous polymer processing technologies such as blown film extrusion or foam extrusion. Rheotens tests were conducted to investigate the influence of plasticizer content on elongational flow properties of cellulose acetate (CA). Triethyl [...] Read more.
Elongational flow properties of polymer melts are very important for numerous polymer processing technologies such as blown film extrusion or foam extrusion. Rheotens tests were conducted to investigate the influence of plasticizer content on elongational flow properties of cellulose acetate (CA). Triethyl citrate (TEC) was used as plasticizer. Melt strength decreases whereas melt extensibility increases with increasing plasticizer content. Melt strength was further studied as a function of zero shear viscosity. The typical draw resonance of the Rheotens curve shifts to higher drawdown velocity and the amplitude of the draw resonance decreases with increasing TEC content. With respect to foam extrusion, not only are melt strength and melt extensibility important but the elongational behavior at low strain rates and the area under the Rheotens curve are also significant. Therefore, elongational viscosity as well as specific energy input were calculated and investigated with respect to plasticizer content. Preliminary foam extrusion tests of externally plasticized CA using chemical blowing agents confirm the results from rheological characterization. Full article
(This article belongs to the Special Issue Polymers from Biomass)
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Open AccessArticle Coarse-Grained Models for Protein-Cell Membrane Interactions
Polymers 2013, 5(3), 890-936; doi:10.3390/polym5030890
Received: 26 April 2013 / Revised: 20 June 2013 / Accepted: 20 June 2013 / Published: 2 July 2013
Cited by 10 | PDF Full-text (13847 KB) | HTML Full-text | XML Full-text
Abstract
The physiological properties of biological soft matter are the product of collective interactions, which span many time and length scales. Recent computational modeling efforts have helped illuminate experiments that characterize the ways in which proteins modulate membrane physics. Linking these models across [...] Read more.
The physiological properties of biological soft matter are the product of collective interactions, which span many time and length scales. Recent computational modeling efforts have helped illuminate experiments that characterize the ways in which proteins modulate membrane physics. Linking these models across time and length scales in a multiscale model explains how atomistic information propagates to larger scales. This paper reviews continuum modeling and coarse-grained molecular dynamics methods, which connect atomistic simulations and single-molecule experiments with the observed microscopic or mesoscale properties of soft-matter systems essential to our understanding of cells, particularly those involved in sculpting and remodeling cell membranes. Full article
(This article belongs to the Special Issue Multiscale Simulations in Soft Matter)
Open AccessArticle Supramolecular Functionalities Influence the Thermal Properties, Interactions and Conductivity Behavior of Poly(ethylene glycol)/LiAsF6 Blends
Polymers 2013, 5(3), 937-953; doi:10.3390/polym5030937
Received: 6 May 2013 / Revised: 20 June 2013 / Accepted: 20 June 2013 / Published: 4 July 2013
Cited by 4 | PDF Full-text (366 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we tethered terminal uracil groups onto short-chain poly(ethylene glycol) (PEG) to form the polymers, uracil (U)-PEG and U-PEG-U. Through AC impedance measurements, we found that the conductivities of these polymers increased upon increasing the content of the lithium salt, [...] Read more.
In this study, we tethered terminal uracil groups onto short-chain poly(ethylene glycol) (PEG) to form the polymers, uracil (U)-PEG and U-PEG-U. Through AC impedance measurements, we found that the conductivities of these polymers increased upon increasing the content of the lithium salt, LiAsF6, until the Li-to-PEG ratio reached 1:4, with the conductivities of the LiAsF6/U-PEG blends being greater than those of the LiAsF6/U-PEG-U blends. The ionic conductivity of the LiAsF6/U-PEG system reached as high as 7.81 × 10−4 S/cm at 30 °C. Differential scanning calorimetry, wide-angle X-ray scattering, 7Li nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy revealed that the presence of the uracil groups in the solid state electrolytes had a critical role in tuning the glass transition temperatures and facilitating the transfer of Li+ ions. Full article
(This article belongs to the Special Issue Supramolecular Chemistry and Self-Assembly)
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Open AccessArticle DNA-Promoted Auto-Assembly of Gold Nanoparticles: Effect of the DNA Sequence on the Stability of the Assemblies
Polymers 2013, 5(3), 1041-1055; doi:10.3390/polym5031041
Received: 26 June 2013 / Revised: 12 July 2013 / Accepted: 15 July 2013 / Published: 22 July 2013
Cited by 3 | PDF Full-text (755 KB) | HTML Full-text | XML Full-text
Abstract
The use of deoxyribonucleic acid (DNA) oligonucleotides has proven to be a powerful and versatile strategy to assemble nanomaterials into two (2D) and three-dimensional (3D) superlattices. With the aim of contributing to the elucidation of the factors that affect the stability of [...] Read more.
The use of deoxyribonucleic acid (DNA) oligonucleotides has proven to be a powerful and versatile strategy to assemble nanomaterials into two (2D) and three-dimensional (3D) superlattices. With the aim of contributing to the elucidation of the factors that affect the stability of this type of superlattices, the assembly of gold nanoparticles grafted with different DNA oligonucleotides was characterized by UV-Vis absorption spectroscopy as a function of temperature. After establishing an appropriate methodology the effect of (i) the length of the grafted oligonucleotides; (ii) the length of their complementary parts and also of (iii) the simultaneous grafting of different oligonucleotides was investigated. Our results indicate that the electrostatic repulsion between the particles and the cooperativity of the assembly process play crucial roles in the stability of the assemblies while the grafting density of the oligonucleotide strands seems to have little influence. Full article
(This article belongs to the Special Issue Supramolecular Chemistry and Self-Assembly)
Open AccessArticle Preparation and Characterization of Poly(ethyl hydrazide) Grafted Oil Palm Empty Fruit Bunch for Removal of Ni(II) Ion in Aqueous Environment
Polymers 2013, 5(3), 1056-1067; doi:10.3390/polym5031056
Received: 22 May 2013 / Accepted: 2 July 2013 / Published: 25 July 2013
Cited by 2 | PDF Full-text (229 KB) | HTML Full-text | XML Full-text
Abstract
Poly(ethyl hydrazide) grafted oil palm empty fruit bunch (peh-g-opefb) fiber has been successfully prepared by heating poly(methylacrylate)-g-opefb at 60 °C for 4 h in a solution of hydrazine hydrate in ethanol. The chelating ability of peh-g-opefb was evaluated based on removal of [...] Read more.
Poly(ethyl hydrazide) grafted oil palm empty fruit bunch (peh-g-opefb) fiber has been successfully prepared by heating poly(methylacrylate)-g-opefb at 60 °C for 4 h in a solution of hydrazine hydrate in ethanol. The chelating ability of peh-g-opefb was evaluated based on removal of Ni(II) ions in aqueous solution. Adsorption of Ni(II) by peh-g-opefb was characterized based on effect of pH, isotherm, kinetic and thermodynamic study. This cheap sorbent based on oil palm empty fruit bunch fiber has a great future potential in water treatment industries based on high adsorption capacity, biodegradability and renewability. Full article
Open AccessArticle Electrochemical and Spectroelectrochemical Properties of a New Donor–Acceptor Polymer Containing 3,4-Dialkoxythiophene and 2,1,3-Benzothiadiazole Units
Polymers 2013, 5(3), 1068-1080; doi:10.3390/polym5031068
Received: 30 May 2013 / Revised: 23 July 2013 / Accepted: 5 August 2013 / Published: 12 August 2013
Cited by 2 | PDF Full-text (801 KB) | HTML Full-text | XML Full-text
Abstract
A new heteroarylene-vinylene donor-acceptor low bandgap polymer, the poly(DEHT-V-BTD), containing vinylene-spaced efficient donor (dialkoxythiophene) and acceptor (benzothiadiazole) moieties, is presented. Electropolymerization has been carried out by several electrochemical techniques and the results are compared. In particular, the pulsed potentiostatic method was able [...] Read more.
A new heteroarylene-vinylene donor-acceptor low bandgap polymer, the poly(DEHT-V-BTD), containing vinylene-spaced efficient donor (dialkoxythiophene) and acceptor (benzothiadiazole) moieties, is presented. Electropolymerization has been carried out by several electrochemical techniques and the results are compared. In particular, the pulsed potentiostatic method was able to provide layers with sufficient amounts of material. Cyclic voltammetries showed reversible behavior towards both p- and n-doping. The HOMO, LUMO, and bandgap energies were estimated to be −5.3, −3.6 and 1.8 eV, respectively. In situ UV-Vis measurements have established that the presence of the vinylene group stabilizes the formation of polaronic charge carriers even at high doping levels. Full article
(This article belongs to the Special Issue Semiconducting Polymers for Organic Electronic Devices)
Open AccessArticle Synthesis and Solution Properties of Double Hydrophilic Poly(ethylene oxide)-block-poly(2-ethyl-2-oxazoline) (PEO-b-PEtOx) Star Block Copolymers
Polymers 2013, 5(3), 1081-1101; doi:10.3390/polym5031081
Received: 28 June 2013 / Revised: 27 July 2013 / Accepted: 19 August 2013 / Published: 2 September 2013
Cited by 10 | PDF Full-text (2122 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We demonstrate the synthesis of star-shaped poly(ethylene oxide)-block-poly(2-ethyl-2-oxazoline) [PEOm-b-PEtOxn]x block copolymers with eight arms using two different approaches, either the “arm-first” or the “core-first” strategy. Different lengths of the outer PEtOx blocks ranging [...] Read more.
We demonstrate the synthesis of star-shaped poly(ethylene oxide)-block-poly(2-ethyl-2-oxazoline) [PEOm-b-PEtOxn]x block copolymers with eight arms using two different approaches, either the “arm-first” or the “core-first” strategy. Different lengths of the outer PEtOx blocks ranging from 16 to 75 repeating units were used, and the obtained materials [PEO28-b-PEtOxx]8 were characterized via size exclusion chromatography (SEC), nuclear magnetic resonance spectroscopy (NMR), and Fourier-transform infrared spectroscopy (FT-IR) measurements. First investigations regarding the solution behavior in water as a non-selective solvent revealed significant differences. Whereas materials synthesized via the “core-first” method seemed to be well soluble (unimers), aggregation occurred in the case of materials synthesized by the “arm-first” method using copper-catalyzed azide-alkyne click chemistry. Full article
(This article belongs to the Special Issue Non-Equilibrium Blockcopolymer Self-Assembly)
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Open AccessArticle Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles
Polymers 2013, 5(3), 1102-1114; doi:10.3390/polym5031102
Received: 1 July 2013 / Revised: 5 August 2013 / Accepted: 29 August 2013 / Published: 6 September 2013
Cited by 11 | PDF Full-text (1018 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar [...] Read more.
Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs) via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter) of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide) (PB-PEO)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation. Full article
(This article belongs to the Special Issue Supramolecular Chemistry and Self-Assembly)
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Open AccessArticle Enzymatic Synthesis and Characterization of Thermosensitive Polyester with Pendent Ketoprofen
Polymers 2013, 5(3), 1158-1168; doi:10.3390/polym5031158
Received: 8 August 2013 / Revised: 2 September 2013 / Accepted: 9 September 2013 / Published: 23 September 2013
Cited by 1 | PDF Full-text (270 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Three linear polyesters with pendant ketoprofen were synthesized by copolymerization of polyethylene glycol (PEG) with malic acid (thiomalic acid or aspartic acid) using lipase B acrylic resin from Candida antarctica (CAL-B) at 90 °C respectively. These thermosensitive polyesters exhibit a lower critical [...] Read more.
Three linear polyesters with pendant ketoprofen were synthesized by copolymerization of polyethylene glycol (PEG) with malic acid (thiomalic acid or aspartic acid) using lipase B acrylic resin from Candida antarctica (CAL-B) at 90 °C respectively. These thermosensitive polyesters exhibit a lower critical solution temperature (LCST) at 10–12 °C. The in vitro study demonstrated that these polyesters could release ketoprofen in neutral and alkaline medium but showed hydrolytic stability in acid medium. These results suggest that, with pendant drugs, these thermosensitive polyesters have potential applications in biomedical materials. Full article
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Review

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Open AccessReview Design Strategies for Functionalized Poly(2-oxazoline)s and Derived Materials
Polymers 2013, 5(3), 956-1011; doi:10.3390/polym5030956
Received: 17 June 2013 / Revised: 1 July 2013 / Accepted: 2 July 2013 / Published: 15 July 2013
Cited by 30 | PDF Full-text (1138 KB) | HTML Full-text | XML Full-text
Abstract
The polymer class of poly(2-oxazoline)s currently is under intensive investigation due to the versatile properties that can be tailor-made by the variation and manipulation of the functional groups they bear. In particular their utilization in the biomedic(in)al field is the subject of [...] Read more.
The polymer class of poly(2-oxazoline)s currently is under intensive investigation due to the versatile properties that can be tailor-made by the variation and manipulation of the functional groups they bear. In particular their utilization in the biomedic(in)al field is the subject of numerous studies. Given the mechanism of the cationic ring-opening polymerization, a plethora of synthetic strategies exists for the preparation of poly(2-oxazoline)s with dedicated functionality patterns, comprising among others the functionalization by telechelic end-groups, the incorporation of substituted monomers into (co)poly(2-oxazoline)s, and polymeranalogous reactions. This review summarizes the current state-of-the-art of poly(2-oxazoline) preparation and showcases prominent examples of poly(2-oxazoline)-based materials, which are retraced to the desktop-planned synthetic strategy and the variability of their properties for dedicated applications. Full article
(This article belongs to the Special Issue Ring-Opening Polymerization)
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Open AccessReview Precise Synthesis of Block Polymers Composed of Three or More Blocks by Specially Designed Linking Methodologies in Conjunction with Living Anionic Polymerization System
Polymers 2013, 5(3), 1012-1040; doi:10.3390/polym5031012
Received: 27 May 2013 / Revised: 27 June 2013 / Accepted: 28 June 2013 / Published: 17 July 2013
Cited by 10 | PDF Full-text (751 KB) | HTML Full-text | XML Full-text
Abstract
This article reviews the successful development of two specially designed linking methodologies in conjunction with a living anionic polymerization system for the synthesis of novel multiblock polymers, composed of three or more blocks, difficult to be synthesized by sequential polymerization. The first [...] Read more.
This article reviews the successful development of two specially designed linking methodologies in conjunction with a living anionic polymerization system for the synthesis of novel multiblock polymers, composed of three or more blocks, difficult to be synthesized by sequential polymerization. The first methodology with the use of a new heterofunctional linking agent, 2-(4-chloromethylphenyl)ethyldimethylchlorosilane (1), was developed for the synthesis of multiblock polymers containing poly(dimethylsiloxane) (PDMS) blocks. This methodology is based on the selective reaction of the chain-end silanolate anion of living PDMS, with the silyl chloride function of 1, and subsequent linking reaction of the resulting ω-chain-end-benzyl chloride-functionalized polymer with either a living anionic polymer or living anionic block copolymer. With this methodology, various multiblock polymers containing PDMS blocks, up to the pentablock quintopolymer, were successfully synthesized. The second methodology using an α-phenylacrylate (PA) reaction site was developed for the synthesis of multiblock polymers composed of all-vinyl polymer blocks. In this methodology, an α-chain-end-PA-functionalized polymer or block copolymer, via the living anionic polymerization, was first prepared and, then, reacted with appropriate living anionic polymer or block copolymer to link the two polymer chains. As a result, ACB (BCA), BAC (CAB), (AB)n, (AC)n, ABA, ACA, BCB, and ABCA multiblock polymers, where A, B, and C were polystyrene, poly(2-vinylpyridine), and poly(methyl methacrylate) segments, could be successfully synthesized. The synthesis of triblock copolymers, BAB, CAC, and CBC, having molecular asymmetry in both side blocks, was also achieved. Furthermore, the use of living anionic polymers, derived from many other monomers, categorized as either of styrene, 2-vinylpyridine, or methyl methacrylate in monomer reactivity, in the linking methodology enabled the number of synthetically possible block polymers to be greatly increased. Once again, all of the block polymers synthesized by these methodologies are new and cannot be synthesized at all by sequential polymerization. They were well-defined in block architecture and precisely controlled in block segment. Full article
(This article belongs to the Special Issue Non-Equilibrium Blockcopolymer Self-Assembly)
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Open AccessReview Nanomembranes and Nanofibers from Biodegradable Conducting Polymers
Polymers 2013, 5(3), 1115-1157; doi:10.3390/polym5031115
Received: 24 June 2013 / Revised: 26 August 2013 / Accepted: 5 September 2013 / Published: 17 September 2013
Cited by 18 | PDF Full-text (4177 KB) | HTML Full-text | XML Full-text
Abstract
This review provides a current status report of the field concerning preparation of fibrous mats based on biodegradable (e.g., aliphatic polyesters such as polylactide or polycaprolactone) and conducting polymers (e.g., polyaniline, polypirrole or polythiophenes). These materials have potential biomedical applications (e.g., tissue [...] Read more.
This review provides a current status report of the field concerning preparation of fibrous mats based on biodegradable (e.g., aliphatic polyesters such as polylactide or polycaprolactone) and conducting polymers (e.g., polyaniline, polypirrole or polythiophenes). These materials have potential biomedical applications (e.g., tissue engineering or drug delivery systems) and can be combined to get free-standing nanomembranes and nanofibers that retain the better properties of their corresponding individual components. Systems based on biodegradable and conducting polymers constitute nowadays one of the most promising solutions to develop advanced materials enable to cover aspects like local stimulation of desired tissue, time controlled drug release and stimulation of either the proliferation or differentiation of various cell types. The first sections of the review are focused on a general overview of conducting and biodegradable polymers most usually employed and the explanation of the most suitable techniques for preparing nanofibers and nanomembranes (i.e., electrospinning and spin coating). Following sections are organized according to the base conducting polymer (e.g., Sections 4–6 describe hybrid systems having aniline, pyrrole and thiophene units, respectively). Each one of these sections includes specific subsections dealing with applications in a nanofiber or nanomembrane form. Finally, miscellaneous systems and concluding remarks are given in the two last sections. Full article
(This article belongs to the Special Issue Semiconducting Polymers for Organic Electronic Devices)
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