scholarly journals Sequence of Polyurethane Ionomers Determinative for Core Structure of Surfactant–Copolymer Complexes

2020 ◽  
Vol 22 (1) ◽  
pp. 337
Author(s):  
Elizabeth M. Timmers ◽  
Jose Rodrigo Magana ◽  
Sandra M. C. Schoenmakers ◽  
P. Michel Fransen ◽  
Henk M. Janssen ◽  
...  
Keyword(s):  
High Water ◽  
High Water Content ◽  
Radius Of Gyration ◽  
Surfactant Micelles ◽  
The Core ◽  
Monomer Sequence ◽  
X Ray Scattering ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Oppositely Charged

The core of micelles self-assembled from amphiphiles is hydrophobic and contains little water, whereas complex coacervate core micelles co-assembled from oppositely charged hydrophilic polymers have a hydrophilic core with a high water content. Co-assembly of ionic surfactants with ionic-neutral copolymers yields surfactant–copolymer complexes known to be capable of solubilizing both hydrophilic and hydrophobic cargo within the mixed core composed of a coacervate phase with polyelectrolyte-decorated surfactant micelles. Here we formed such complexes from asymmetric (PUI-A2) and symmetric (PUI-S2), sequence-controlled polyurethane ionomers and poly(N-methyl-2-vinylpyridinium iodide)29-b-poly(ethylene oxide)204 copolymers. The complexes with PUI-S2 were 1.3-fold larger in mass and 1.8-fold larger in radius of gyration than the PUI-A2 complexes. Small-angle X-ray scattering revealed differences in the packing of the similarly sized PUI micelles within the core of the complexes. The PUI-A2 micelles were arranged in a more ordered fashion and were spaced further apart from each other (10 nm vs. 6 nm) than the PUI-S2 micelles. Hence, this work shows that the monomer sequence of amphiphiles can be varied to alter the internal structure of surfactant–copolymer complexes. Since the structure of the micellar core may affect both the cargo loading and release, our findings suggest that these properties may be tuned through control of the monomer sequence of the micellar constituents.

scholarly journals Effect of Molecular Architecture on Associating Behavior of Star-Like Amphiphilic Polymers Consisting of Plural Poly(ethylene oxide) and One Alkyl Chain

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 460
Author(s):  
Daisuke Kugimoto ◽  
Aoi Taniguchi ◽  
Masaki Kinoshita ◽  
Isamu Akiba
Keyword(s):  
Ethylene Oxide ◽  
Average Molecular Weight ◽  
Amphiphilic Polymers ◽  
Hydrophobic Core ◽  
Molecular Architecture ◽  
Polymer Micelles ◽  
The Core ◽  
X Ray Scattering ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

Associating behavior of star-like amphiphilic polymers consisting of two or three poly(ethylene oxide) (PEO) chains and one stearyl chain (C18) was investigated. Although the aggregation number (Nagg) of linear analogue of amphiphilic polymers monotonically decreased with increasing number-average molecular weight of PEO (Mn,PEO), the Nagg of micelles of star-like amphiphilic polymers with Mn,PEO = 550 g/mol was smaller than that with Mn,PEO = 750 g/mol, whereas that with Mn,PEO ≥ 750 g/mol showed general Mn,PEO dependence. Small-angle X-ray scattering analyses revealed that the occupied area of one PEO chain on the interface between hydrophobic core and corona layer in the micelles of star-like polymers was much narrower than that in the linear amphiphilic polymers. This result indica ted the PEO chains of star-like polymers partially took unfavorable conformation near the core–corona interface in polymer micelles. The effect of local conformation of PEO chains near the interface on the associating behavior became significant as Mn,PEO decreased. Therefore, in polymer micelles of star-like amphiphilic polymers containing PEO with Mn,PEO = 550 g/mol, the enlargement of occupied area of PEO on the core–corona interface should be caused to avoid the formation of unfavorable conformations of partial PEO chains, resulting in a decrease in Naggs.

Gel Dehydration by Spontaneous Imbibition of Brine From Aged Polymer Gel

SPE Journal ◽  
2013 ◽  
Vol 19 (01) ◽  
pp. 122-134 ◽  
Author(s):  
B.. Brattekås ◽  
Å.. Haugen ◽  
A.. Graue ◽  
R.S.. S. Seright
Keyword(s):  
Fractured Reservoirs ◽  
High Water ◽  
Spontaneous Imbibition ◽  
High Water Content ◽  
Polymer Gel ◽  
Fracture Conductivity ◽  
The Core ◽  
Gel Layer ◽  
Gel Treatment ◽  
Pressure Resistance

Summary This work investigates dehydration of polymer gel by capillary imbibition of water bound in gel into a strongly water-wet matrix. Polymer gel is a crosslinked-polymer solution of high water content, where water can leave the gel and propagate through porous media, whereas the large 3D polymer-gel structures cannot. In fractured reservoirs, polymer gel can be used for conformance control by reducing fracture conductivity. Dehydration of polymer gel by spontaneous imbibition (SI) contributes to shrinkage of the gel, which may open parts of the initially gel-filled fracture to flow and significantly reduce the pressure resistance of the gel treatment. SI of water bound in aged Cr(III)-acetate-hydrolized-polyacrcylamide (HPAM) gel was observed and quantified. Oil-saturated chalk-core plugs were submerged in gel, and the rate of SI was measured. Two boundary conditions were tested: all faces open (AFO) and two-end-open oil-water (TEO-OW), where one end was in contact with the imbibing fluid (gel or brine) and the other was in contact with oil. The rate of SI was significantly slower in gel compared with brine, and was highly sensitive to the ratio of matrix volume to surface open to flow, decreasing with increasing ratios. The presence of a dehydrated gel layer on the core surface lowered the rate of imbibition; continuous loss of water to the core increased the gel layer concentration and thus the barrier to flow between the core and fresh gel. Severe gel dehydration and shrinkage up to 99% were observed in the experiments, suggesting that gel treatments may lose efficiency over time in field applications where a potential for SI exists. The implications of gel dehydration by SI, and its relevance in field applications, are discussed for both gel and gelant field treatments.

Photodegradation Activity of Poly(ethylene oxide-b-ε-caprolactone)-Templated Mesoporous TiO2 Coated with Au and Pt

2020 ◽  
Vol 20 (8) ◽  
pp. 5276-5281 ◽  
Author(s):  
Wei-Cheng Chu ◽  
Jeonghun Kim ◽  
Minjun Kim ◽  
Abdulmohsen Ali Alshehri ◽  
Yousef Gamaan Alghamidi ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Self Assembly ◽  
Diblock Copolymers ◽  
Charge Carriers ◽  
Nanocomposite Films ◽  
Soft Template ◽  
X Ray Scattering ◽  
Evaporation Induced Self Assembly ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

Mesoporous TiO2 films are synthesized through evaporation-induced self-assembly using poly(ethylene oxide-b-ε-caprolactone) diblock copolymers as a soft-template. Using small-angle X-ray scattering and scanning electron microscopy, we investigate the effect of the TiO2/PEO-b-PCL ratio on the resulting nanoarchitectonic structure. After sputter-coating Au and Pt layers, these Au/TiO2 and Pt/TiO2 nanocomposite films display drastically enhanced photodegradation of rhodamine 6G under ultraviolet irradiation, due to the metal films inhibiting the rapid recombination of photogenerated charge carriers.

scholarly journals Micelle Structure Details and Stabilities of Cyclic Block Copolymer Amphiphile and Its Linear Analogues

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 163 ◽  
Author(s):  
Brian J. Ree ◽  
Toshifumi Satoh ◽  
Takuya Yamamoto
Keyword(s):  
Structural Integrity ◽  
Positive Impact ◽  
Structural Parameters ◽  
Micelle Formation ◽  
Cyclic Polymer ◽  
X Ray Scattering ◽  
Micelle Structure ◽  
Cyclic Block ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

In this study, we investigate structures and stabilities of the micelles of a cyclic amphiphile (c-PBA-b-PEO) composed of poly(-n-butyl acrylate) (PBA) and poly(ethylene oxide) (PEO) blocks and its linear diblock and triblock analogues (l-PBA-b-PEO and -l-PBA--b-PEO-b-PBA) by using synchrotron X-ray scattering and quantitative data analysis. The comprehensive scattering analysis gives details and insights to the micellar architecture through structural parameters. Furthermore, this analysis provides direct clues for structural stabilities in micelles, which can be used as a good guideline to design highly stable micelles. Interestingly, in water, all topological polymers are found to form ellipsoidal micelles rather than spherical micelles; more interestingly, the cyclic polymer and its linear triblock analog make oblate-ellipsoidal micelles while the linear diblock analog makes a prolate-ellipsoidal micelle. The analysis results collectively inform that the cyclic topology enables more compact micelle formation as well as provides a positive impact on the micellar structural integrity.

SAXS characterization of polymer-embedded hollow nanoparticles and of their shell porosity

2013 ◽  
Vol 46 (6) ◽  
pp. 1654-1664 ◽  
Author(s):  
Zhi Hong Chen ◽  
Sun Hye Hwang ◽  
Xiang-bing Zeng ◽  
Jongmin Roh ◽  
Jyongsik Jang ◽  
...  
Keyword(s):  
Gas Adsorption ◽  
Alternative Form ◽  
Outer Diameter ◽  
Hollow Nanoparticles ◽  
Polymer Layers ◽  
X Ray Scattering ◽  
Poly Ethylene Oxide ◽  
Inner Diameter ◽  
Poly Ethylene

Size parameters of SiO2/TiO2hollow nanoparticles (HNPs) of 25–100 nm in diameter were characterized by small-angle X-ray scattering (SAXS). On the basis of the decoupling and the Percus–Yevick approximations, and using a hollow sphere model, size information on HNPs was extracted, including average outer diameter, average inner diameter and polydispersity. Application of an alternative form factor based on hollow ellipsoids, and of a sticky hard sphere structure factor, did not improve the fit significantly. The shell porosity of the HNPs and the size of the pores in the HNP shell were further characterized by combining SAXS with gas adsorption methods. The above HNPs were then supported on a porous poly(ethylene oxide) scaffold by freeze drying from aqueous solution. To characterize the product, a multishell model was applied to fit the experimental SAXS curves and extract the following morphological information: distribution of HNPs between the surface and interior of the polymer, thickness of the polymer layers lining the outer and inner surfaces of HNPs, and densities of the outer and inner polymer layers. The work demonstrates the versatility of SAXS in obtaining key information on dissolved and polymer-supported HNPs in applications such as drug delivery and catalysis.

Investigation of the Melting Behavior of the Alternating PEO/PCL Multiblock Copolymer by SAXS and WAXS

2001 ◽  
Vol 711 ◽  
Author(s):  
Tae Chul Kim ◽  
Jong Ho Kim ◽  
Hyun Hwi Lee ◽  
You Han Bae ◽  
Do Young Noh
Keyword(s):  
Domain Size ◽  
Melting Behavior ◽  
X Ray ◽  
Multiblock Copolymer ◽  
X Ray Scattering ◽  
Integrated Intensity ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Increasing Temperature ◽  
Crystalline Domains

ABSTRACTThe melting of the semicrystalline poly(ethylene oxide)(PEO)/ poly(ε -caprolactone) (PCL) multiblock copolymer was investigated by small and wide angle x-ray scattering. The two-stage melting was found in which the PEO block and the PCL block melt independently. The crystalline PEO Bragg peaks disappear at 30.5 °C while the block spacing increases due to the chain relaxation. The PEO crystalline domain size decreases continuously in proportion to the amount of the crystalline part. Above 40 °C, the PCL lamellae domains started to melt and the integrated intensity of the PCL Bragg peak decreases with increasing temperature. In the case of the PCL, however, the crystal domain size decreases only slightly. This indicates that the number of the PCL crystalline domains decreases during the melting.

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