Formation of Amphiphilic Block Copolymer Micelles in Nonaqueous Solution**Acknowledgements: BC gratefully acknowledge the support of their work by the Department of Energy (DEFGO286ER45237.012), and the National Center for Human Genome Research (1R01HG0138601). He also wishes to thank many of his colleagues and scientists who have graciously sent him their reprints and preprints, in particular to A. Eisenberg, I.A. Katime, A.P. Gast, T. Nose, C. Frank, S.P. Nunes and J.L. Fulton.

Liu, T.; Liu, L.-Z.; Chu, Benjamin

doi:10.1016/b978-044482441-7/50007-4

Cited by 13 publications

(5 citation statements)

References 129 publications

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“…However, PS 981 –PEO 773 micelles show higher retention times under the same conditions. The increased retention can be attributed to the expected increase in Z owing to the larger core forming PS block. , As a result, PS 981 –PEO 773 micelles have approximately three times the Z of PS 385 –PEO 636 .…”

Section: Results and Discussionmentioning

confidence: 99%

Characterization of Complex Polymer Self-Assemblies and Large Aggregates by Multidetector Thermal Field-Flow Fractionation

2017

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Micelles prepared from amphiphilic block copolymers (ABCs) have found numerous applications in pharmaceutical, electronics, environmental, cosmetics, and hygiene industries. These micelles, whether in the pure or mixed micelle form, often exist as multiple morphologies (spherical, cylindrical, worm, or vesicular) in equilibrium with each other. However, none of the current column-based fractionation techniques or any microscopic technique are capable of a successful separation, identification, and quantitation of these complex self-assemblies with regards to morphology, size, molar mass, and chemical composition in one experiment. Multidetector thermal field-flow fractionation (ThFFF) is shown to be capable of separating and characterizing not only pure micelles but also mixed micelles prepared from polystyrene-poly(ethylene oxide) ABCs. In addition, multidetector ThFFF is demonstrated to be capable of successfully characterizing multiple micellar morphological evolutions (induced by the addition of an electrolyte) and thus showcasing the potential of this novel approach to monitor the formation of polymer self-assemblies with multiple and complex morphological distributions.

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Section: Results and Discussionmentioning

confidence: 99%

Characterization of Complex Polymer Self-Assemblies and Large Aggregates by Multidetector Thermal Field-Flow Fractionation

2017

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“…The linear correlation between the gravimetric asphaltene concentration and the ELSD signal, as shown in the previous section, seems to indicate an aggregation process that is proportional to the asphaltene concentration in the crude oil, related to the number of molecules participating in the aggregates. This is not dissimilar to other aggregation processes that occur on nonaqueous solution of surfactants and polymers that also indicated an increase in the number of compounds forming part of the aggregates as their concentration increases. As expected, aggregation is limited by the solubility of these compounds in the solvent.…”

Section: Results and Discussionmentioning

confidence: 99%

Evaluating Asphaltenes by Size Exclusion Chromatography

Rogel,

Dutta

2023

Energy Fuels

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Size exclusion chromatography (SEC) has been used extensively to characterize asphaltenes, crude oils, and petroleum products. These studies have provided significant insights into the nature and behavior of this material. This work presents a couple of new applications that use this technique. First, a new methodology is presented for determining the asphaltene content based on using a SEC column. This new method shows good repeatability, and the results correlate with the gravimetric standard method ASTM D6560. Second, we explored the SEC behavior of a series of different asphaltenes injected at low concentrations (10−500 ppm) using an evaporative light scattering detector. The analysis of the changes in relative areas of the peaks in the chromatogram revealed a break in the behavior between 50 and 100 ppm which could have been associated with the existence of a critical nanoaggregate concentration (CNAC). However, based on the presence of significant peaks (∼30−40% of the total area) corresponding to asphaltene aggregates even at concentrations as low as 10 ppm, this break cannot correspond to a CNAC, instead it might be associated with a transition to a different aggregation mechanism. This work also explores the SEC behavior of asphaltenes precipitated using different solvents from the same crude oil and shows how the aggregation is correlated to the solvent used to obtain the asphaltenes, while the aggregate sizes are related to the average characteristics of the molecules that precipitate using each solvent.

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“…In this context, remarkable differences exist between the glass transition temperatures ( T g ) of either i- and s-PMMA or 1.2- and 1.4-PBd, and as a result significant differences in chain flexibility of the respective cores are expected. Thus, under similar experimental conditions, these self-assemblies will naturally have significant differences in their respective solvophobic–solvophilic balance index, which in turn is essential in governing the size and morphology of self-assemblies. , …”

Section: Resultsmentioning

confidence: 99%

Stereocomplexation of Polymers in Micelle Nanoreactors As Studied by Multiple Detection Thermal Field-Flow Fractionation

2018

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In this study the thermally induced in situ stereocomplexation (SC) of binary blends of symmetrical isotactic and syndiotactic polymethymethacrylates (i-and s-PMMAs) inside micellar nanoreactors (MNR) with polystyrene (PS) shells is investigated using thermal field-flow fractionation (ThFFF) as a separation technique. The MNRs are prepared from three systematic binary blending ratios of pure micelles of i-PMMA-PS and s-PMMA-PS in a nonsolvent for PMMAs in order to produce mixed micelles with a binary microstructural composition of the interior PMMA cores. The SC of these stereoregular PMMA cores inside the MNRs is shown to be thermally induced as a function of annealing temperatures from room temperature up to 150 °C. This SC is initially confirmed by Fourier transform infrared spectroscopy (FTIR), whereby signal shifts are observed in the carbonyl absorption regions. These signal shifts are as a result of SC interactions between adjacent ester and alphamethyl groups. Furthermore, temperature-dependent dynamic light scattering (DLS) results show that MNRs with more SC domains have a much more drastic reduction in size. Additional corroboration is provided by multiple detection ThFFF results which show significant differences in retentions and sizes between MNRs with stereocomplexed cores and those without. Ratios of i-PMMA:s-PMMA in the order of 1:1, 1:2, and 2:1 were investigated with all ratios exhibiting thermal annealing induced SC, of which the 1:2 ratio is shown to have the highest predisposition to SC.

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Cited by 13 publications

References 129 publications

Characterization of Complex Polymer Self-Assemblies and Large Aggregates by Multidetector Thermal Field-Flow Fractionation

Characterization of Complex Polymer Self-Assemblies and Large Aggregates by Multidetector Thermal Field-Flow Fractionation

Evaluating Asphaltenes by Size Exclusion Chromatography

Stereocomplexation of Polymers in Micelle Nanoreactors As Studied by Multiple Detection Thermal Field-Flow Fractionation

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