Superlattices in block copolymer blends with attractive interactions

e-Polymers ◽  
2001 ◽  
Vol 1 (1) ◽  
Author(s):  
Kirsten Markgraf ◽  
Volker Abetz
Keyword(s):  
Electron Microscopy ◽  
Triblock Copolymer ◽  
Diblock Copolymers ◽  
Triblock Copolymers ◽  
Mechanical Analysis ◽  
Butyl Methacrylate ◽  
Mixed Solution ◽  
Copolymer Blends ◽  
Transmission Electron ◽  
Cyclohexyl Methacrylate

AbstractBlends of microphase separated polystyrene-block-polybutadiene-blockpoly( methacrylic acid) triblock copolymers (SBA) with polystyrene-block-poly(2- vinylpyridine) (SV) or poly(2-vinylpyridine)-block-poly(cyclohexyl methacrylate) (VC) diblock copolymers were prepared and characterized. Attractive segmental interactions through hydrogen bonds between A and V could be monitored by infrared spectroscopy and dynamic mechanical analysis. Common superlattices were obtained by casting from a mixed solution of these block copolymers in tetrahydrofuran and were investigated by transmission electron microscopy. Varying the amount of hydrogen bonding donors via controlled saponification of an SBT triblock copolymer (T: poly(tert-butyl methacrylate)) lead to different superlattices in blends with a VC diblock copolymer.

Effect of Additive Constraint on the Morphological and Mechanical Properties of Triblock Copolymer Blends

1996 ◽  
Vol 461 ◽  
Author(s):  
L. Kane ◽  
D. A. Norman ◽  
S. A. White ◽  
R. J. Spontak
Keyword(s):  
Electron Microscopy ◽  
Diblock Copolymer ◽  
Triblock Copolymer ◽  
Morphological Characteristics ◽  
Mechanical Analysis ◽  
Molecular Weights ◽  
Copolymer Blends ◽  
Transmission Electron ◽  
Copolymer Blend

ABSTRACTWhile numerous studies have addressed the morphological characteristics of diblock copolymer blends either with a second copolymer or a parent homopolymer, relatively few have examined comparable blends containing a triblock copolymer. In this study, we investigate the role of mid-block bridging on the morphological and physical characteristics of blends composed of a poly(styrene-b-isoprene-b-styrene) (SIS) triblock copolymer with either an unconstrained homo-polyisoprene (hI) or an end-grafted SI diblock copolymer. Blend compositions and molecular weights of the hi, as well as the I-block of the copolymer, have all been systematically varied to elucidate the effect of additive constraint on the extent of nonideal intramicrodomain mixing. Blend morphologies are characterized using transmission electron microscopy, while blend properties have been measured by dynamic mechanical analysis.

Formation of superlattices in blends of 3-miktoarm star terpolymers with diblock copolymers

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Volker Abetz ◽  
Shimei Jiang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Diblock Copolymers ◽  
Shell Structures ◽  
Core Shell ◽  
Transmission Electron ◽  
Miktoarm Star ◽  
Triblock Terpolymers ◽  
Cyclohexyl Methacrylate

Abstract In this contribution we report on the morphological structures formed in blends of microphase-separated 3-miktoarm star terpolymers of polystyrene-armpolybutadiene- arm-poly(2-vinylpyridine) (SBV*) and polystyrene-block-polybutadiene (SB), polystyrene-block-poly(2-vinylpyridine) (SV), poly(2-vinylpyridine)- block-poly(cyclohexyl methacrylate) (VC) diblock copolymers. The morphologies are characterized by transmission electron microscopy. Blends with similar morphologies as known from linear triblock terpolymers are found, like core-shell structures based on cylinders or gyroids. Other blends show very distorted morphologies, or morphologies similar to the ones found for pure 3-miktoarm star terpolymers. While attractive interactions between blocks of the two species enhance the formation of common superlattices, blends with too large diblock copolymers tend to macrophase-separate.

Novel pattern formation in blends of asymmetric ABC triblock terpolymers

e-Polymers ◽  
2004 ◽  
Vol 4 (1) ◽  
Author(s):  
Volker Abetz ◽  
Shimei Jiang ◽  
Astrid Göpfert
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Diblock Copolymers ◽  
Morphological Characterization ◽  
Core Shell ◽  
Specific Interactions ◽  
Transmission Electron ◽  
Triblock Terpolymers ◽  
Cyclohexyl Methacrylate ◽  
Macrophase Separation

Abstract A series of polystyrene-block-poly(1,2-butadiene)-block-poly(2-vinylpyridine) (SBV) triblock terpolymers were used to prepare blends with symmetric polystyrene-block-poly(2-vinylpyridine) (SV) and poly(2-vinylpyridine)-block-poly- (cyclohexyl methacrylate) (VC) diblock copolymers. Morphological characterization was carried out by transmission electron microscopy. These triblock terpolymers self-assemble into various core-shell type or lamellar morphologies. In the SBV/SV blends, macrophase separation between the two block copolymers, continuous centrosymmetric lamellae and stacks of non-centrosymmetric lamellae with antiparallel orientation were found. In the blends of SBV/VC, macrophase separation was never observed, what is due to the specific interactions between S and C domains. These systems showed among other morphologies also a cylindrical morphology in which rings surround the cylinders.

Examination of Extra Electron Diffraction Spots Observed in Deuterium-Irradiated Silicon by Using Parallel Electron Beam Illumination

1990 ◽  
Vol 48 (2) ◽  
pp. 490-491
Author(s):  
Ryuichiro Oshima ◽  
Shoichiro Honda ◽  
Tetsuo Tanabe
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Silicon Single Crystal ◽  
Mixed Solution ◽  
Parallel Beam ◽  
Defect Clusters ◽  
Float Zone ◽  
Transmission Electron ◽  
Extra Electron ◽  
Diffraction Patterns

In order to examine the origin of extra diffraction spots and streaks observed in selected area diffraction patterns of deuterium irradiated silicon, systematic diffraction experiments have been carried out by using parallel beam illumination.Disc specimens 3mm in diameter and 0.5mm thick were prepared from a float zone silicon single crystal(B doped, 7kΩm), and were chemically thinned in a mixed solution of nitric acid and hydrogen fluoride to make a small hole at the center for transmission electron microscopy. The pre-thinned samples were irradiated with deuterium ions at temperatures between 300-673K at 20keV to a dose of 1022ions/m2, and induced lattice defects were examined under a JEOL 200CX electron microscope operated at 160kV.No indication of formation of amorphous was obtained in the present experiments. Figure 1 shows an example of defects induced by irradiation at 300K with a dose of 2xl021ions/m2. A large number of defect clusters are seen in the micrograph.

scholarly journals Study on Structure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1426
Author(s):  
Tomáš Remiš ◽  
Petr Bělský ◽  
Tomáš Kovářík ◽  
Jaroslav Kadlec ◽  
Mina Ghafouri Azar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Analysis ◽  
Single Step ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Primary Particles ◽  
Solution Casting Method ◽  
Average Size

In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

scholarly journals Dissipative Particle Dynamics Study on Interfacial Properties of Symmetric Ternary Polymeric Blends

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1516
Author(s):  
Dongmei Liu ◽  
Kai Gong ◽  
Ye Lin ◽  
Tao Liu ◽  
Yu Liu ◽  
...  
Keyword(s):  
Interfacial Tension ◽  
Chain Length ◽  
Triblock Copolymer ◽  
Diblock Copolymers ◽  
Triblock Copolymers ◽  
Dissipative Particle Dynamics ◽  
Interfacial Properties ◽  
Particle Dynamics ◽  
Polymeric Blends ◽  
Polymer Component

We investigated the interfacial properties of symmetric ternary An/AmBm/Bn and An/Am/2BmAm/2/Bn polymeric blends by means of dissipative particle dynamics (DPD) simulations. We systematically analyzed the effects of composition, chain length, and concentration of the copolymers on the interfacial tensions, interfacial widths, and the structures of each polymer component in the blends. Our simulations show that: (i) the efficiency of the copolymers in reducing the interfacial tension is highly dependent on their compositions. The triblock copolymers are more effective in reducing the interfacial tension compared to that of the diblock copolymers at the same chain length and concentration; (ii) the interfacial tension of the blends increases with increases in the triblock copolymer chain length, which indicates that the triblock copolymers with a shorter chain length exhibit a better performance as the compatibilizers compared to that of their counterparts with longer chain lengths; and (iii) elevating the triblock copolymer concentration can promote copolymer enrichment at the center of the interface, which enlarges the width of the phase interfaces and reduces the interfacial tension. These findings illustrate the correlations between the efficiency of copolymer compatibilizers and their detailed molecular parameters.

Organoclay-reinforced polyethersulfone-modified epoxy-based hybrid nanocomposites

2011 ◽  
Vol 23 (7) ◽  
pp. 526-534 ◽  
Author(s):  
Yang Wang ◽  
Boming Zhang ◽  
Jinrui Ye
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Electron Microscope ◽  
Optical Microscope ◽  
Mechanical Analysis ◽  
Hybrid Nanocomposites ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Modified Epoxy ◽  
Scanning Electron

Hybrid nanocomposites were successfully prepared by the incorporation of polyethersulfone (PES) and organoclay into epoxy resin. They had higher fracture toughness than the prepared PES/epoxy blend and organoclay/epoxy nanocomposites. The microstructures of the hybrid nanocomposites were studied. They were comprised of homogeneous PES/epoxy semi-interpenetrating network (semi-IPN) matrices and organoclay micro-agglomerates made up of tactoid-like regions composed of ordered exfoliated organoclay with various orientations. The former was confirmed with dynamic mechanical analysis, scanning electron microscopy and transmission electron microscopy, while the latter was successfully observed with X-ray diffraction measurements, optical microscope, scanning electron microscope and transmission electron microscope. The improvement of their fracture toughness was due to the synergistic toughening effect of the PES and the organoclay and related to their microstructures.

scholarly journals Influence of Uncoupled Diblock Molecules on Mechanical Properties of Styerene/Butadiene/ Styrene Triblock Copolymers

2012 ◽  
Vol 12 ◽  
pp. 149-156 ◽  
Author(s):  
Rameshwar Adhikari
Keyword(s):  
Mechanical Properties ◽  
Block Copolymers ◽  
Tensile Deformation ◽  
Triblock Copolymers ◽  
Large Strain ◽  
Deformation Behaviour ◽  
Mechanical Analysis ◽  
Transmission Electron ◽  
Star Block Copolymers ◽  
Butadiene Styrene

The influence of the presence of uncoupled polystyrene-block-polybutadiene (SB) diblock chains to polystyrene-block-polybutadiene-block-polystyrene (SBS) triblock copolymers on the mechanical properties of the latter has been studied by means of tensile testing and dynamic mechanical analysis preparing several lamellae forming SBS/ SB blends through solution casting. The microphase-separated morphology of the samples was investigated by transmission electron microscopy. Both large strain deformation tensile deformation behaviour and viscoelastic properties of the SBS block copolymers were found to be affected appreciably by the presence of uncoupled SB diblock. The storage modulus of linear SBS was found to drop more sharply in the plateau region than for the radial SBS at the same SB content. At low SB content (up to 20 wt.-% for linear SBS and still higher for radial one), the overall tensile properties was not negatively influenced. On the whole, star block copolymers were found to be less sensitive towards the presence of diblock.DOI: http://dx.doi.org/10.3126/njst.v12i0.6493 Nepal Journal of Science and Technology 12 (2011) 149-156

scholarly journals Polymeric Self-Assemblies Based on tetra-ortho-Substituted Azobenzene as Visible Light Responsive Nanocarriers

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2060
Author(s):  
Alejandro Roche ◽  
Luis Oriol ◽  
Rosa M. Tejedor ◽  
Milagros Piñol
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Diblock Copolymers ◽  
Uv Light ◽  
Morphological Changes ◽  
Nile Red ◽  
Green Light ◽  
Light Irradiation ◽  
Transmission Electron ◽  
Amphiphilic Diblock Copolymers

Most of reported polymeric light-responsive nanocarriers make use of UV light to trigger morphological changes and the subsequent release of encapsulated cargoes. Moving from UV- to visible-responsive units is interesting for the potential biomedical applications of these materials. Herein we report the synthesis by ring opening polymerization (ROP) of a series of amphiphilic diblock copolymers, into which either UV or visible responsive azobenzenes have been introduced via copper(I) catalyzed azide-alkyne cycloaddition (CuAAC). These copolymers are able to self-assemble into spherical micelles or vesicles when dispersed in water. The study of the response of the self-assemblies upon UV (365 nm) or visible (530 or 625 nm) light irradiation has been studied by Transmission Electron Microscopy (TEM), Cryogenic Transmission Electron Microscopy (Cryo-TEM), and Dynamic Light Scattering (DLS) studies. Encapsulation of Nile Red, in micelles and vesicles, and Rhodamine B, in vesicles, and its light-stimulated release has been studied by fluorescence spectroscopy and confocal microscopy. Appreciable morphological changes have been induced with green light, and the subsequent release of encapsulated cargoes upon green light irradiation has been confirmed.

Synthesis and Photocatalytic Activity of Visible-Light Responsive BiOBr/GO Composites

2017 ◽  
Vol 751 ◽  
pp. 807-812
Author(s):  
Tuangphorn Prasitthikun ◽  
X. Wu ◽  
Tsugio Sato ◽  
Charusporn Mongkolkachit ◽  
Pornapa Sujaridworakun
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Visible Light ◽  
High Efficiency ◽  
Precipitation Method ◽  
Mixed Solution ◽  
Diffuse Reflection Spectroscopy ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Photocatalytic Activities

High efficiency BiOBr/GO composites photocatalyst were successfully synthesized via a facile precipitation method. The precursors were prepared by dissolving Bi (NO3)3.5H2O and KBr in glycerol and distilled water, respectively. Various amounts (0.1-2 wt%) of graphene oxide were added into the mixed solution precursors, and stirred at room temperature to get precipitated powder without further heat treatment. The obtained products were characterized for phase, morphology, optical properties and surface area by X-ray diffraction (XRD), transmission electron microscopy (TEM), filed-emission scanning electron microscopy (FE-SEM), UV-Vis diffuse reflection spectroscopy (DRS) and Brunauer–Emmett–Teller (BET), respectively. The morphology and structure of as-synthesized samples were composed of numerous fine plates of BiOBr dispersed on the GO sheets. The photocatalytic activities of BiOBr/GO composites were evaluated by rhodamine B degradation under visible light irradiation. As the results, the significant increase in photodegradation of BiOBr/GO composite comparing with pure BiOBr was observed. Among all samples, the composite with 1 wt% of graphene oxide showed the highest photocatalytic performance.

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