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Title: Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering

Abstract

A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.

Authors:
 [1]; ORCiD logo [1];  [2];  [1];  [1];  [1];  [3];  [3];  [2];  [4]
  1. Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
  2. Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States
  3. Department of Biological Sciences, Illinois Institute of Technology, Chicago, Illinois 60616, United States
  4. Department of Chemical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States; Department of Biopharmaceutical Sciences, University of Illinois at Chicago, Chicago, Illinois 60612, United States
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
National Institutes of Health (NIH)
OSTI Identifier:
1418031
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Macro Letters; Journal Volume: 6; Journal Issue: 9
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE

Citation Formats

Szymusiak, Magdalena, Kalkowski, Joseph, Luo, Hanying, Donovan, Alexander J., Zhang, Pin, Liu, Chang, Shang, Weifeng, Irving, Thomas, Herrera-Alonso, Margarita, and Liu, Ying. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering. United States: N. p., 2017. Web. doi:10.1021/acsmacrolett.7b00490.
Szymusiak, Magdalena, Kalkowski, Joseph, Luo, Hanying, Donovan, Alexander J., Zhang, Pin, Liu, Chang, Shang, Weifeng, Irving, Thomas, Herrera-Alonso, Margarita, & Liu, Ying. Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering. United States. doi:10.1021/acsmacrolett.7b00490.
Szymusiak, Magdalena, Kalkowski, Joseph, Luo, Hanying, Donovan, Alexander J., Zhang, Pin, Liu, Chang, Shang, Weifeng, Irving, Thomas, Herrera-Alonso, Margarita, and Liu, Ying. 2017. "Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering". United States. doi:10.1021/acsmacrolett.7b00490.
@article{osti_1418031,
title = {Core–Shell Structure and Aggregation Number of Micelles Composed of Amphiphilic Block Copolymers and Amphiphilic Heterografted Polymer Brushes Determined by Small-Angle X-ray Scattering},
author = {Szymusiak, Magdalena and Kalkowski, Joseph and Luo, Hanying and Donovan, Alexander J. and Zhang, Pin and Liu, Chang and Shang, Weifeng and Irving, Thomas and Herrera-Alonso, Margarita and Liu, Ying},
abstractNote = {A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. The structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.},
doi = {10.1021/acsmacrolett.7b00490},
journal = {ACS Macro Letters},
number = 9,
volume = 6,
place = {United States},
year = 2017,
month = 8
}
  • A large group of functional nanomaterials employed in biomedical applications, including targeted drug delivery, relies on amphiphilic polymers to encapsulate therapeutic payloads via self-assembly processes. Knowledge of the micelle structures will provide critical insights into design of polymeric drug delivery systems. Core–shell micelles composed of linear diblock copolymers poly(ethylene glycol)-b-poly(caprolactone) (PEG-b-PCL), poly(ethylene oxide)-b-poly(lactic acid) (PEG-b-PLA), as well as a heterografted brush consisting of a poly(glycidyl methacrylate) backbone with PEG and PLA branches (PGMA-g-PEG/PLA) were characterized by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS) measurements to gain structural information regarding the particle morphology, core–shell size, and aggregation number. Themore » structural information at this quasi-equilibrium state can also be used as a reference when studying the kinetics of polymer micellization.« less
  • The amphiphilic block copolymers of vinyl ether were prepared by living cationic polymerization. The partially deuterated copolymers for SANS experiments were especially synthesized by introducing deuterated phenyl units in the hydrophobic chain. SANS measurements were performed for aqueous solutions of these copolymers by changing H{sub 2}O/D{sub 2}O ratios. The SANS profiles indicate that the micelles in the present system exhibit a core-shell structure and that the size and shape of micelles are largely dependent on the length of hydrophobic chain. The micelle of shorter hydrophobic chain was found to be nearly spherical, whereas the micelle of longer hydrophobic chain wasmore » confirmed to have an ellipsoidal shape.« less
  • Highly soluble amphiphilic materials are shown to form aggregates in supercritical CO{sub 2}. The strategy for synthesis of these amphiphilic molecules involves incorporating CO{sub 2}-philic segments that, for this study, are perfluorinated alkyl chains. These CO{sub 2} -philic regions function like the hydrocarbon tails of conventional surfactant molecules used in liquid organic solvents. Synthesis and characterization of three different CO{sub 2} amphiphiles are reported. Subsequent small angle X-ray scattering (SAXS) measurements were used to characterize the aggregation of these materials in supercritical CO{sub 2}. Each of the three amphiphiles studied showed a different type of aggregation behavior. A graft copolymermore » consisting of a CO{sub 2}-philic backbone and CO{sub 2}-phobic grafts associated into a micellar structure in the presence of water to promote hydrogen bonding. These aggregates contain approximately 600 grafts in the core. The commercially available surfactant perfluoroalkylpoly( ethylene oxide), or F(CF{sub 2}){sub 6-10}CH{sub 2} CH{sub 2}O(CH{sub 2}CH{sub 2}O){sub 3-8}H, forms classic reverse micelle structures having radii of about 84 A under the conditions of high pressure required to solubilize the material. A third amphiphile, the semifluorinated alkane diblock molecule F(CF{sub 2}){sub 10}(CH{sub 2}){sub 10}H, may form small aggregates of at most 4 unimers per aggregate. 41 refs., 10 figs., 1 tab.« less
  • Self-assembly and its influence on the photophysical properties of polystyrene-b-sulfonated poly (1,3-cyclohexadiene) (PS-b-sPCHD) were investigated using transmission electron microscopy (TEM), laser light scattering (LLS) technique, and fluorescence spectroscopy. The amphiphilic PS-b-sPCHD copolymers can associate to form micelles with insoluble PS segments as the core surrounded by soluble sPCHD segments in aqueous media. J-aggregation of the chromophores in sPCHD segments is significantly facilitated in the micellization, resulting in a remarkable change in the photophysical properties of PS-b-sPCHD.
  • A complex coacervate is a fluid phase that results from the electrostatic interactions between two oppositely charged macromolecules. The nature of the coacervate core structure of hydrogels and micelles formed from complexation between pairs of diblock or triblock copolymers containing oppositely charged end-blocks as a function of polymer and salt concentration was investigated. Both ABA triblock copolymers of poly[(allyl glycidyl ether)-b-(ethylene oxide)-b-(allyl glycidyl ether)] and analogous poly[(allyl glycidyl ether)-b-(ethylene oxide)] diblock copolymers, which were synthesized to be nearly one-half of the symmetrical triblock copolymers, were studied. The poly(allyl glycidyl ether) blocks were functionalized with either guanidinium or sulfonate groups viamore » postpolymerization modification. Mixing of oppositely charged block copolymers resulted in the formation of nanometer-scale coacervate domains. Small angle neutron scattering (SANS) experiments were used to investigate the size and spacing of the coacervate domains. The SANS patterns were fit using a previously vetted, detailed model consisting of polydisperse core–shell micelles with a randomly distributed sphere or body-centered cubic (BCC) structure factor. For increasing polymer concentration, the size of the coacervate domains remained constant while the spatial extent of the poly(ethylene oxide) (PEO) corona decreased. However, increasing salt concentration resulted in a decrease in both the coacervate domain size and the corona size due to a combination of the electrostatic interactions being screened and the shrinkage of the neutral PEO blocks. Additionally, for the triblock copolymers that formed BCC ordered domains, the water content in the coacervate domains was calculated to increase from approximately 16.8% to 27.5% as the polymer concentration decreased from 20 to 15 wt %.« less