Polymers

Research

16 pages, 8684 KiB

Open AccessArticle

Block Copolymer Elastomer with Graphite Filler: Effect of Processing Conditions and Silane Coupling Agent on the Composite Properties

by Denis Mihaela Panaitescu, Raluca Augusta Gabor, Cristian Andi Nicolae, Anca Constantina Parau, Catalin Vitelaru, Valentin Raditoiu and Mircea Chipara

Polymers 2018, 10(1), 46; https://doi.org/10.3390/polym10010046 - 4 Jan 2018

Cited by 17 | Viewed by 6345

Abstract

The control of morphology and interface in poly(styrene-ethylene/butylene-styrene) (SEBS) composites with graphitic fillers is extremely important for the design of piezoresistive sensors for body motion or flexible temperature sensors. The effects of a high amount of graphite (G) and silane coupling agent on [...] Read more.

The control of morphology and interface in poly(styrene-ethylene/butylene-styrene) (SEBS) composites with graphitic fillers is extremely important for the design of piezoresistive sensors for body motion or flexible temperature sensors. The effects of a high amount of graphite (G) and silane coupling agent on the morphology and properties of SEBS composites with anisotropic mechanical properties are reported. The physical and chemical bonding of silane to both G and SEBS surface was proved by EDX and TGA results; this improved interface influenced both the thermal and mechanical properties of the composite. The vinyltriethoxysilane (VS) promoted the formation of char residue and, being tightly bound to both SEBS and G, did not show separate decomposition peak in the TGA curve of composites. The mechanical properties were measured on two perpendicular directions and were improved by both the addition of VS and the increased amount of G; however, the increase of storage modulus due to orientation (from 5 to 15 times depending on the composition and direction of the test) was more important than that provided by the increase of G concentration, which was a maximum of four times that obtained for 15 wt % graphite. A mechanism to explain the influence of G content and treatment on the variation of storage modulus and tan δ depending on the direction of the test was also proposed. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

1999 KiB

Open AccessArticle

Calculation of the Contact Angle of Polymer Melts on Tool Surfaces from Viscosity Parameters

by Gernot Zitzenbacher, Hannes Dirnberger, Manuel Längauer and Clemens Holzer

Polymers 2018, 10(1), 38; https://doi.org/10.3390/polym10010038 - 30 Dec 2017

Cited by 28 | Viewed by 7766

Abstract

It is of great importance for polymer processing whether and how viscosity influences the wettability of tool surfaces. We demonstrate the existence of a distinct relationship between the contact angle of molten polymers and zero shear viscosity in this paper. The contact angle [...] Read more.

It is of great importance for polymer processing whether and how viscosity influences the wettability of tool surfaces. We demonstrate the existence of a distinct relationship between the contact angle of molten polymers and zero shear viscosity in this paper. The contact angle of molten polypropylene and polymethylmethacrylate on polished steel was studied in a high temperature chamber using the sessile drop method. A high pressure capillary rheometer with a slit die was employed to determine the shear viscosity curves in a low shear rate range. A linear relation between the contact angle and zero shear viscosity was obtained. Furthermore, the contact angle and the zero shear viscosity values of the different polymers were combined to one function. It is revealed that, for the wetting of tool surfaces by molten polymers, a lower viscosity is advantageous. Furthermore, a model based on the temperature shift concept is proposed which allows the calculation of the contact angle of molten polymers on steel for different temperatures directly from shear viscosity data. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

3001 KiB

Open AccessArticle

Presenting Precision Glycomacromolecules on Gold Nanoparticles for Increased Lectin Binding

by Sophia Boden, Kristina G. Wagner, Matthias Karg and Laura Hartmann

Polymers 2017, 9(12), 716; https://doi.org/10.3390/polym9120716 - 14 Dec 2017

Cited by 30 | Viewed by 9015 | Correction

Abstract

Glyco-functionalized gold nanoparticles have great potential as biosensors and as inhibitors due to their increased binding to carbohydrate-recognizing receptors such as the lectins. Here we apply previously developed solid phase polymer synthesis to obtain a series of precision glycomacromolecules that allows for straightforward [...] Read more.

Glyco-functionalized gold nanoparticles have great potential as biosensors and as inhibitors due to their increased binding to carbohydrate-recognizing receptors such as the lectins. Here we apply previously developed solid phase polymer synthesis to obtain a series of precision glycomacromolecules that allows for straightforward variation of their chemical structure as well as functionalization of gold nanoparticles by ligand exchange. A novel building block is introduced allowing for the change of spacer building blocks within the macromolecular scaffold going from an ethylene glycol unit to an aliphatic spacer. Furthermore, the valency and overall length of the glycomacromolecule is varied. All glyco-functionalized gold nanoparticles show high degree of functionalization along with high stability in buffer solution. Therefore, a series of measurements applying UV-Vis spectroscopy, dynamic light scattering (DLS) and surface plasmon resonance (SPR) were performed studying the aggregation behavior of the glyco-functionalized gold nanoparticles in presence of model lectin Concanavalin A. While the multivalent presentation of glycomacromolecules on gold nanoparticles (AuNPs) showed a strong increase in binding compared to the free ligands, we also observed an influence of the chemical structure of the ligand such as its valency or hydrophobicity on the resulting lectin interactions. The straightforward variation of the chemical structure of the precision glycomacromolecule thus gives access to tailor-made glyco-gold nanoparticles (glyco-AuNPs) and fine-tuning of their lectin binding properties. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

2691 KiB

Open AccessArticle

Simple and High Yield Synthesis of Metal-Polymer Nanocomposites: The Role of Theta-Centrifugation as an Essential Purification Step

by Patrick Hummel, Arne Lerch, Sebastian Manfred Goller, Matthias Karg and Markus Retsch

Polymers 2017, 9(12), 659; https://doi.org/10.3390/polym9120659 - 30 Nov 2017

Cited by 8 | Viewed by 6680

Abstract

Nanocomposites are an important materials class, which strives to foster synergistic effects from the intimate mixture of two vastly different materials. Inorganic nanoparticles decorated with polymer ligands, for instance, aim to combine the processing flexibility of polymers with the mechanical robustness of solid [...] Read more.

Nanocomposites are an important materials class, which strives to foster synergistic effects from the intimate mixture of two vastly different materials. Inorganic nanoparticles decorated with polymer ligands, for instance, aim to combine the processing flexibility of polymers with the mechanical robustness of solid state materials. The fabrication and purification of such composite nanoparticles, however, still presents a synthetic challenge. Here, we present a simple synthesis of silver polystyrene nanocomposites with a controllable interparticle distance. The interparticle distance can be well-controlled with a few nanometer precision using polystyrene ligands with various molecular weights. The nanoparticle and polymer ligand synthesis yield both materials on gram scales. Consequently, the polymer nanocomposites can also be fabricated in such large amounts. Most importantly, we introduce Θ-centrifugation as a purification method, which is capable of purifying large nanocomposite batches in a reproducible manner. We employ a range of characterization methods to prove the successful purification procedure, such as transmission electron microscopy, thermogravimetric analysis, and dynamic light scattering. Our contribution will be of high interest for many groups working on nanocomposite materials, where the sample purification has been a challenge up to now. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

2193 KiB

Open AccessArticle

Ionic Conductivity and Assembled Structures of Imidazolium Salt-Based Block Copolymers with Thermoresponsive Segments

by Kazuhiro Nakabayashi, Yu Sato, Yuta Isawa, Chen-Tsyr Lo and Hideharu Mori

Polymers 2017, 9(11), 616; https://doi.org/10.3390/polym9110616 - 15 Nov 2017

Cited by 9 | Viewed by 5871

Abstract

Ionic liquid-based block copolymers composed of ionic (solubility tunable)–nonionic (water-soluble and thermoresponsive) segments were synthesized to explore the relationship between ionic conductivity and assembled structures. Three block copolymers, comprising poly(N-vinylimidazolium bromide) (poly(NVI-Br)) as a hydrophilic poly(ionic liquid) segment and thermoresponsive poly( [...] Read more.

Ionic liquid-based block copolymers composed of ionic (solubility tunable)–nonionic (water-soluble and thermoresponsive) segments were synthesized to explore the relationship between ionic conductivity and assembled structures. Three block copolymers, comprising poly(N-vinylimidazolium bromide) (poly(NVI-Br)) as a hydrophilic poly(ionic liquid) segment and thermoresponsive poly(N-isopropylacrylamide) (poly(NIPAM)), having different compositions, were initially prepared by RAFT polymerization. The anion-exchange reaction of the poly(NVI-Br) in the block copolymers with lithium bis(trifluoromethanesulfonyl)imide (LiNTf₂) proceeded selectively to afford amphiphilic block copolymers composed of hydrophobic poly(NVI-NTf₂) and hydrophilic poly(NIPAM). Resulting poly(NVI-NTf₂)-b-poly(NIPAM) exhibited ionic conductivities greater than 10⁻³ S/cm at 90 °C and 10⁻⁴ S/cm at 25 °C, which can be tuned by the comonomer composition and addition of a molten salt. Temperature-dependent ionic conductivity and assembled structures of these block copolymers were investigated, in terms of the comonomer composition, nature of counter anion and sample preparation procedure. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

2998 KiB

Open AccessArticle

A Facile and Effective Method to Fabricate Superhydrophobic/Superoeophilic Surface for the Separation of Both Water/Oil Mixtures and Water-in-Oil Emulsions

by Feiran Li, Ziran Wang, Yunlu Pan and Xuezeng Zhao

Polymers 2017, 9(11), 563; https://doi.org/10.3390/polym9110563 - 30 Oct 2017

Cited by 15 | Viewed by 4647

Abstract

Superhydrophobic/superoleophilic surfaces (water contact angle greater than 150° with low hysteresis, with an oil contact angle smaller than 5°) have a wide-range of applications in oil/water separation. However, most of the essential methods to fabricate this kind of surface are complex, inflexible, and [...] Read more.

Superhydrophobic/superoleophilic surfaces (water contact angle greater than 150° with low hysteresis, with an oil contact angle smaller than 5°) have a wide-range of applications in oil/water separation. However, most of the essential methods to fabricate this kind of surface are complex, inflexible, and costly. Moreover, most methods focus on separating immiscible oil and water mixtures but lack the ability to demulsify surfactant-stabilized emulsions, which is widely present in industry and daily life. In this study, a facile and effective method was developed to fabricate superhydrophobic/superoleophilic surfaces that can be easily applied on almost all kinds of solid substrates. The treated porous substrates (e.g., steel mesh; cotton) can separate oil/water mixtures or absorb oil from a mixture. Furthermore, the compressed treated cotton is capable of demulsifying stabilized water-in-oil emulsions with high efficiency. The simple, low-cost, and material-unrestricted method provides an efficient way to separate oil/water mixtures of various kinds and has great potential in energy conservation and environmental protection. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Figure 1

4325 KiB

Open AccessArticle

Properties of Electrospun Nanofibers of Multi-Block Copolymers of [Poly-ε-caprolactone-b-poly(tetrahydrofuran-co-ε-caprolactone)]_m Synthesized by Janus Polymerization

by Muhammad Ijaz Shah, Zhening Yang, Yao Li, Liming Jiang and Jun Ling

Polymers 2017, 9(11), 559; https://doi.org/10.3390/polym9110559 - 27 Oct 2017

Cited by 18 | Viewed by 4641 | Correction

Abstract

Novel biodegradable multiblock copolymers of [PCL-b-P(THF-co-CL)]_m with PCL fractions of 53.3 and 88.4 wt % were prepared by Janus polymerization of ε-caprolactone (CL) and tetrahydrofuran (THF). Their electrospun mats were obtained with optimized parameters containing bead-free nanofibers whose [...] Read more.

Novel biodegradable multiblock copolymers of [PCL-b-P(THF-co-CL)]_m with PCL fractions of 53.3 and 88.4 wt % were prepared by Janus polymerization of ε-caprolactone (CL) and tetrahydrofuran (THF). Their electrospun mats were obtained with optimized parameters containing bead-free nanofibers whose diameters were between 290 and 520 nm. The mechanical properties of the nanofiber scaffolds were measured showing the tensile strength and strain at break of 8–10 MPa and 123–161%, respectively. Annealing improved their mechanical properties and their tensile strength and strain at break of the samples increased to 10–13 MPa and 267–338%, respectively. Due to the porous structure and crystallization in nanoscale confinement, the mechanical properties of the nanofiber scaffolds appeared as plastics, rather than as the elastomers observed in bulk thermal-molded film. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

4112 KiB

Open AccessArticle

Optimisation of Surface-Initiated Photoiniferter-Mediated Polymerisation under Confinement, and the Formation of Block Copolymers in Mesoporous Films

by Jessica C. Tom, Robert Brilmayer, Johannes Schmidt and Annette Andrieu-Brunsen

Polymers 2017, 9(10), 539; https://doi.org/10.3390/polym9100539 - 23 Oct 2017

Cited by 24 | Viewed by 8427

Abstract

Nature as the ultimate inspiration can direct, gate, and selectively transport species across channels to fulfil a specific targeted function. Harnessing such precision over local structure and functionality at the nanoscale is expected to lead to indispensable developments in synthetic channels for application [...] Read more.

Nature as the ultimate inspiration can direct, gate, and selectively transport species across channels to fulfil a specific targeted function. Harnessing such precision over local structure and functionality at the nanoscale is expected to lead to indispensable developments in synthetic channels for application in catalysis, filtration and sensing, and in drug delivery. By combining mesoporous materials with localised charge-switchable poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, precisely controlling pore filling and exploring the possibility of incorporating two different responsive polymers, we hope to approach the precision control of natural systems in the absence of an external force. Here, we report a simple one-step approach to prepare a mesoporous silica thin film with ~8 nm pores functionalised with a photoiniferter by combining sol–gel chemistry and evaporation-induced self-assembly (EISA). We show that surface-initiated photoiniferter-mediated polymerisation (SI-PIMP) allows the incorporation of a high polymer content up to geometrical pore blocking by the simple application of UV light in the presence of a monomer and solvent, proceeding in a controlled manner in pore sizes below 10 nm, with the potential to tune the material properties through the formation of surface-grafted block copolymers. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

1916 KiB

Open AccessArticle

Ferrocene-Modified Block Copolymers for the Preparation of Smart Porous Membranes

by Sebastian Schöttner, Rimjhim Hossain, Christian Rüttiger and Markus Gallei

Polymers 2017, 9(10), 491; https://doi.org/10.3390/polym9100491 - 8 Oct 2017

Cited by 24 | Viewed by 7461

Abstract

The design of artificially generated channels featuring distinct remote-switchable functionalities is of critical importance for separation, transport control, and water filtration applications. Here, we focus on the preparation of block copolymers (BCPs) consisting of polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) having molar [...] Read more.

The design of artificially generated channels featuring distinct remote-switchable functionalities is of critical importance for separation, transport control, and water filtration applications. Here, we focus on the preparation of block copolymers (BCPs) consisting of polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) having molar masses in the range of 91 to 124 kg mol⁻¹ with a PHEMA content of 13 to 21 mol %. The BCPs can be conveniently functionalized with redox-active ferrocene moieties by a postmodification protocol for the hydrophilic PHEMA segments. Up to 66 mol % of the hydroxyl functionalities can be efficiently modified with the reversibly redox-responsive units. For the first time, the ferrocene-containing BCPs are shown to form nanoporous integral asymmetric membranes by self-assembly and application of the non-solvent-induced phase separation (SNIPS) process. Open porous structures are evidenced by scanning electron microscopy (SEM) and water flux measurements, while efficient redox-switching capabilities are investigated after chemical oxidation of the ferrocene moieties. As a result, the porous membranes reveal a tremendously increased polarity after oxidation as reflected by contact angle measurements. Additionally, the initial water flux of the ferrocene-containing membranes decreased after oxidizing the ferrocene moieties because of oxidation-induced pore swelling of the membrane. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Figure 1

2742 KiB

Open AccessArticle

Fabrication of Hypericin Imprinted Polymer Nanospheres via Thiol-Yne Click Reaction

by Yuxin Pei, Fengfeng Fan, Xinxin Wang, Weiwei Feng, Yong Hou and Zhichao Pei

Polymers 2017, 9(10), 469; https://doi.org/10.3390/polym9100469 - 24 Sep 2017

Cited by 12 | Viewed by 5518

Abstract

To fabricate molecularly imprinted polymer nanospheres via click reaction, five different clickable compounds were synthesized and two types of click reactions (azide-alkyne and thiol-yne) were explored. It was found that molecularly imprinted polymer nanospheres could be successfully synthesized via thiol-yne click reaction using [...] Read more.

To fabricate molecularly imprinted polymer nanospheres via click reaction, five different clickable compounds were synthesized and two types of click reactions (azide-alkyne and thiol-yne) were explored. It was found that molecularly imprinted polymer nanospheres could be successfully synthesized via thiol-yne click reaction using 3,5-diethynyl-pyridine (1) as the monomer, tris(3-mercaptopropionate) (tri-thiol, 5) as the crosslinker, and hypericin as the template (MIP–NSHs). The click polymerization completed in merely 4 h to produce the desired MIP–NSHs, which were characterized by FTIR, SEM, DLS, and BET, respectively. The reaction conditions for adsorption capacity and selectivity towards hypericin were optimized, and the MIP–NSHs synthesized under the optimized conditions showed a high adsorption capacity (Q = 6.03 μmol•g−1) towards hypericin. The imprinting factors of MIP–NSHs towards hypericin, protohypericin, and emodin were 2.44, 2.88, and 2.10, respectively. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

5643 KiB

Open AccessArticle

Preparation and Characterization of Thermo-Responsive Rod-Coil Diblock Copolymers

by Yang-Yen Yu, Wen-Chen Chien and Chia-Liang Tsai

Polymers 2017, 9(8), 340; https://doi.org/10.3390/polym9080340 - 4 Aug 2017

Cited by 2 | Viewed by 3719

Abstract

In this study, we synthesized amphiphilic poly(2,7–(9,9–dioctylfluorene))–block–N,N–(diisopropylamino)ethyl methacrylate (POF–b–PDPMAEMA) rod-coil diblock copolymers by atom transfer radical polymerization (ATRP). The structure and multifunctional sensing properties of these copolymers were also investigated. The POF rod segment length of 10 [...] Read more.

In this study, we synthesized amphiphilic poly(2,7–(9,9–dioctylfluorene))–block–N,N–(diisopropylamino)ethyl methacrylate (POF–b–PDPMAEMA) rod-coil diblock copolymers by atom transfer radical polymerization (ATRP). The structure and multifunctional sensing properties of these copolymers were also investigated. The POF rod segment length of 10 was fixed and the PDPAEMA coil segment lengths of 90 and 197 were changed, respectively. The micellar aggregates of POF₁₀–b–PDPAEMA₉₀ rod-coil diblock copolymer in water showed a reversible shape transition from cylinder bundles to spheres when the temperature was changed from 20 to 80 °C or the pH was changed from 11 to 2. The atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements indicated that the temperature had also an obvious influence on the micelle size. In addition, since POF₁₀–b–PDPAEMA₉₀ had a lower critical solution temperature, its photoluminescence (PL) intensity in water is thermoreversible. The PL spectra showed that the POF–b–PDPAEMA copolymer had a reversible on/off profile at elevated temperatures, and thus could be used as an on/off fluorescent indicator for temperature or pH. The fluorescence intensity distribution of pH switched from “off–on” to “on–off” as the temperature increased. These results showed that the POF–b–PDPAEMA copolymer has a potential application for temperature and pH sensing materials. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

3217 KiB

Open AccessArticle

Biodegradable Core–Multishell Nanocarriers: Influence of Inner Shell Structure on the Encapsulation Behavior of Dexamethasone and Tacrolimus

by Michael L. Unbehauen, Emanuel Fleige, Florian Paulus, Brigitta Schemmer, Stefan Mecking, Sam Dylan Moré and Rainer Haag

Polymers 2017, 9(8), 316; https://doi.org/10.3390/polym9080316 - 29 Jul 2017

Cited by 15 | Viewed by 6968

Abstract

We here present the synthesis and characterization of a set of biodegradable core–multishell (CMS) nanocarriers. The CMS nanocarrier structure consists of hyperbranched polyglycerol (hPG) as core material, a hydrophobic (12, 15, 18, 19, and 36 C-atoms) inner and a polyethylene glycol monomethyl ether [...] Read more.

We here present the synthesis and characterization of a set of biodegradable core–multishell (CMS) nanocarriers. The CMS nanocarrier structure consists of hyperbranched polyglycerol (hPG) as core material, a hydrophobic (12, 15, 18, 19, and 36 C-atoms) inner and a polyethylene glycol monomethyl ether (mPEG) outer shell that were conjugated by ester bonds only to reduce the toxicity of metabolites. The loading capacities (LC) of the drugs, dexamethasone and tacrolimus, and the aggregate formation, phase transitions, and degradation kinetics were determined. The intermediate inner shell length (C15) system had the best overall performance with good LCs for both drugs as well as a promising degradation and release kinetics, which are of interest for dermal delivery. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

2974 KiB

Open AccessArticle

Self-Assembly of Double Hydrophilic Poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) Block Copolymers in Aqueous Solution

by Jochen Willersinn and Bernhard V.K.J. Schmidt

Polymers 2017, 9(7), 293; https://doi.org/10.3390/polym9070293 - 20 Jul 2017

Cited by 26 | Viewed by 7068

Abstract

The self-assembly of a novel combination of hydrophilic blocks in water is presented, namely poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) (PEtOx-b-PVP). The completely water-soluble double hydrophilic block copolymer (DHBC) is formed via copper-catalyzed polymer conjugation, whereas the molecular weight of the PVP [...] Read more.

The self-assembly of a novel combination of hydrophilic blocks in water is presented, namely poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) (PEtOx-b-PVP). The completely water-soluble double hydrophilic block copolymer (DHBC) is formed via copper-catalyzed polymer conjugation, whereas the molecular weight of the PVP is varied in order to study the effect of block ratio on the self-assembly process. Studies via dynamic light scattering, static light scattering as well as microscopy techniques, e.g., cryo scanning electron microscopy or laser scanning confocal microscopy, show the formation of spherical particles in an aqueous solution with sizes between 300 and 400 nm. Particles of the DHBCs are formed without the influence of external stimuli. Moreover, the efficiency of self-assembly formation relies significantly on the molar ratio of the utilized blocks. The nature of the formed structures relies further on the concentration, and indications of particular and vesicular structures are found. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

2385 KiB

Open AccessArticle

Electrowetting Performances of Novel Fluorinated Polymer Dielectric Layer Based on Poly(1H,1H,2H,2H-perfluoroctylmethacrylate) Nanoemulsion

by Jiaxin Hou, Wenwen Ding, Yancong Feng, Lingling Shui, Yao Wang, Hao Li, Nan Li and Guofu Zhou

Polymers 2017, 9(6), 217; https://doi.org/10.3390/polym9060217 - 11 Jun 2017

Cited by 3 | Viewed by 6061

Abstract

In electrowetting devices, hydrophobic insulating layer, namely dielectric layer, is capable of reversibly switching surface wettability through applied electric field. It is critically important but limited by material defects in dielectricity, reversibility, film forming, adhesiveness, price and so on. To solve this key [...] Read more.

In electrowetting devices, hydrophobic insulating layer, namely dielectric layer, is capable of reversibly switching surface wettability through applied electric field. It is critically important but limited by material defects in dielectricity, reversibility, film forming, adhesiveness, price and so on. To solve this key problem, we introduced a novel fluorinated polyacrylate—poly(1H,1H,2H,2H-perfluoroctylmethacrylate (PFMA) to construct micron/submicron-scale dielectric layer via facile spray coating of nanoemulsion for replacing the most common Teflon AF series. All the results illustrated that, continuous and dense PFMA film with surface relief less than 20 nm was one-step fabricated at 110 °C, and exhibited much higher static water contact angle of 124°, contact angle variation of 42°, dielectric constant of about 2.6, and breakdown voltage of 210 V than Teflon AF 1600. Particularly, soft and highly compatible polyacrylate mainchain assigned five times much better adhesiveness than common adhesive tape, to PFMA layer. As a promising option, PFMA dielectric layer may further facilitate tremendous development of electrowetting performances and applications. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Figure 1

5867 KiB

Open AccessArticle

Block Copolymer Membranes from Polystyrene-b-poly(solketal methacrylate) (PS-b-PSMA) and Amphiphilic Polystyrene-b-poly(glyceryl methacrylate) (PS-b-PGMA)

by Sarah Saleem, Sofia Rangou, Clarissa Abetz, Brigitte Lademann, Volkan Filiz and Volker Abetz

Polymers 2017, 9(6), 216; https://doi.org/10.3390/polym9060216 - 10 Jun 2017

Cited by 23 | Viewed by 10168

Abstract

In this paper; we compare double hydrophobic polystyrene-b-poly(solketal methacrylate) (PS-b-PSMA) and amphiphilic polystyrene-b-poly(glyceryl methacrylate) (PS-b-PGMA) diblock copolymer membranes which are prepared by combining the block copolymer self-assembly in solution with a non-solvent induced phase separation [...] Read more.

In this paper; we compare double hydrophobic polystyrene-b-poly(solketal methacrylate) (PS-b-PSMA) and amphiphilic polystyrene-b-poly(glyceryl methacrylate) (PS-b-PGMA) diblock copolymer membranes which are prepared by combining the block copolymer self-assembly in solution with a non-solvent induced phase separation (SNIPS). Diblock copolymers (i.e., PS-b-PSMA) were synthesized by sequential living anionic polymerization, whereas polystyrene-b-poly(glyceryl methacrylate) (PS-b-PGMA) were obtained by acid hydrolysis of the acetonide groups of the polysolketal methacrylate (PSMA) blocks into dihydroxyl groups (PGMA). Membrane structures and bulk morphologies were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM); respectively. The resulting PS-b-PGMA diblock copolymers produce an ordered hexagonal cylindrical pore structure during the SNIPS process, while membranes fabricated from the double hydrophobic (PS-b-PSMA) do not under similar experimental conditions. Membrane performance was evaluated by water flux and contact angle measurements. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

1338 KiB

Open AccessCommunication

Anti-Microbial Biopolymer Hydrogel Scaffolds for Stem Cell Encapsulation

by Philipp T. Kühn, René T. Rozenbaum, Estelle Perrels, Prashant K. Sharma and Patrick Van Rijn

Polymers 2017, 9(4), 149; https://doi.org/10.3390/polym9040149 - 22 Apr 2017

Cited by 11 | Viewed by 6951

Abstract

Biopolymer hydrogels are an attractive class of materials for wound dressings and other biomedical applications because of their ease of use and availability from biomass. Here, we present a hydrogel formation approach based on alginate and chitosan. Alginate is conventionally cross-linked using multivalent [...] Read more.

Biopolymer hydrogels are an attractive class of materials for wound dressings and other biomedical applications because of their ease of use and availability from biomass. Here, we present a hydrogel formation approach based on alginate and chitosan. Alginate is conventionally cross-linked using multivalent ions such as Ca²⁺ but in principle any polycationic species can be used such as polyelectrolytes. Exchanging the cross-linking Ca²⁺ ions partially with chitosan, which at pH 7 has available positive charges as well as good interactions with Ca²⁺, leads to an improved Young’s modulus. This gel is non-toxic to mammalian cells and hence allows conveniently for stem cell encapsulation since it is based on two-component mixing and gel formation. Additionally, the chitosan is known to have a bactericidal effect which is retained when using it in the alginate–chitosan gel formation and the formed hydrogels displayed bactericidal effects against P. aeruginosa and S. aureus. The combination of anti-bacterial properties, inclusion of stem cells, and the hydrogel nature would provide an ideal environment for complex wound healing. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

Review

Jump to: Research, Other

28 pages, 8031 KiB

Open AccessReview

Synthesis, Characterization, and Applications of Magnetic Nanoparticles Featuring Polyzwitterionic Coatings

by Philip Biehl, Moritz Von der Lühe, Silvio Dutz and Felix H. Schacher

Polymers 2018, 10(1), 91; https://doi.org/10.3390/polym10010091 - 18 Jan 2018

Cited by 154 | Viewed by 14092

Abstract

Throughout the last decades, magnetic nanoparticles (MNP) have gained tremendous interest in different fields of applications like biomedicine (e.g., magnetic resonance imaging (MRI), drug delivery, hyperthermia), but also more technical applications (e.g., catalysis, waste water treatment) have been pursued. Different surfactants and polymers [...] Read more.

Throughout the last decades, magnetic nanoparticles (MNP) have gained tremendous interest in different fields of applications like biomedicine (e.g., magnetic resonance imaging (MRI), drug delivery, hyperthermia), but also more technical applications (e.g., catalysis, waste water treatment) have been pursued. Different surfactants and polymers are extensively used for surface coating of MNP to passivate the surface and avoid or decrease agglomeration, decrease or modulate biomolecule absorption, and in most cases increase dispersion stability. For this purpose, electrostatic or steric repulsion can be exploited and, in that regard, surface charge is the most important (hybrid) particle property. Therefore, polyelectrolytes are of great interest for nanoparticle coating, as they are able to stabilize the particles in dispersion by electrostatic repulsion due to their high charge densities. In this review article, we focus on polyzwitterions as a subclass of polyelectrolytes and their use as coating materials for MNP. In the context of biomedical applications, polyzwitterions are widely used as they exhibit antifouling properties and thus can lead to minimized protein adsorption and also long circulation times. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

14489 KiB

Open AccessReview

Nucleobase-Containing Polymers: Structure, Synthesis, and Applications

by Haitao Yang and Weixian Xi

Polymers 2017, 9(12), 666; https://doi.org/10.3390/polym9120666 - 1 Dec 2017

Cited by 32 | Viewed by 10062

Abstract

Nucleobase interactions play a fundamental role in biological functions, including transcription and translation. Natural nucleic acids like DNA are also widely implemented in material realm such as DNA guided self-assembly of nanomaterials. Inspired by that, polymer chemists have contributed phenomenal endeavors to mimic [...] Read more.

Nucleobase interactions play a fundamental role in biological functions, including transcription and translation. Natural nucleic acids like DNA are also widely implemented in material realm such as DNA guided self-assembly of nanomaterials. Inspired by that, polymer chemists have contributed phenomenal endeavors to mimic both the structures and functions of natural nucleic acids in synthetic polymers. Similar sequence-dependent responses were observed and employed in the self-assembly of these nucleobase-containing polymers. Here, the structures, synthetic approaches, and applications of nucleobase-containing polymers are highlighted and a brief look is taken at the future development of these polymers. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

► Show Figures

Graphical abstract

Other

Jump to: Research, Review

2 pages, 157 KiB

Open AccessCorrection

Correction: Sophia, B.; et al. Presenting Precision Glycomacromolecules on Gold Nanoparticles for Increased Lectin Binding. Polymers 2017, 9, 716

by Sophia Boden, Kristina G. Wagner, Matthias Karg and Laura Hartmann

Polymers 2019, 11(9), 1426; https://doi.org/10.3390/polym11091426 - 30 Aug 2019

Cited by 1 | Viewed by 1890

Abstract

In the original version of this Article [...] Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

Journal Menu

Journal Browser

Polymers and Block Copolymers at Interfaces and Surfaces

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Related Special Issue

Published Papers (19 papers)

Research

Review

Other

Further Information

Guidelines

MDPI Initiatives

Follow MDPI