1
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Williams ER, van den Bergh W, Stefik M. High- χ, low- N micelles from partially perfluorinated block polymers. SOFT MATTER 2022; 18:7917-7930. [PMID: 36017726 DOI: 10.1039/d2sm00513a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Kinetically trapped ("persistent") micelles enable emerging applications requiring a constant core diameter. Preserving a χN barrier to chain exchange with low-N requires a commensurately higher χcore-solvent for micelle persistence. Low-N, high-χ micelles containing fluorophobic interactions were studied using poly(ethylene oxide-b-perfluorooctyl acrylate)s (O45FX, x = 8, 11) in methanolic solutions. DLS analysis of micelles revealed chain exchange only for O45F8 while SAXS analysis suggested elongated core block conformations commensurate with the contour lengths. Micelle chain exchange from solution perturbations were examined by characterizing their behavior as templates for inorganic materials via SAXS and SEM. In contrast to the F8 analog, the larger χN barrier for the O45F11 enabled persistent micelle behavior in both thin films and bulk samples despite the low Tg micelle core. Careful measures of micelle core diameters and pore sizes revealed that the nanoparticle distribution extended through the corona and 0.52 ± 0.15 nm into the core-corona interface, highlighting thermodynamics favoring both locations simultaneously.
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Affiliation(s)
- Eric R Williams
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
| | - Wessel van den Bergh
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
| | - Morgan Stefik
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
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2
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Han XG, Sun ZH, Liang N, Zhang H. Aggregate behavior in amphiphilic coil/rod block copolymer solutions. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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3
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Heo TY, Kim S, Chen L, Sokolova A, Lee S, Choi SH. Molecular Exchange Kinetics in Complex Coacervate Core Micelles: Role of Associative Interaction. ACS Macro Lett 2021; 10:1138-1144. [PMID: 35549078 DOI: 10.1021/acsmacrolett.1c00482] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecular exchange dynamics between spherical complex coacervate core micelles (C3Ms) are documented using time-resolved small-angle neutron scattering measurements (TR-SANS), and the effects of salt concentration, type of charges, and core block polydispersity to the chain exchange are quantified. Isotopically labeled block copolyelectrolytes were prepared by postpolymerization modification of two nearly identical poly(ethylene oxide-b-allyl glycidyl ether), one with normal and the other with deuterated PEO blocks (i.e., hPEO-PAGE and dPEO-PAGE). The observed rates at multiple salt concentrations are consolidated using time-salt superposition shift factors representing chain exchange rates and analyzed. Our comprehensive analytical relaxation function based on the sticky-Rouse model and the thermodynamic barrier for core block extraction successfully describes the molecular exchange kinetics between the isotopically labeled C3Ms. We believe this work provides fundamental design criteria for C3Ms with engineered chain exchange dynamics.
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Affiliation(s)
- Tae-Young Heo
- Department of Chemical Engineering, Hongik University, Seoul, 04066, Republic of Korea
| | - Sojeong Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, 08826, Republic of Korea
| | - Liwen Chen
- Department of Chemical & Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Anna Sokolova
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales 2234, Australia
| | - Sangwoo Lee
- Department of Chemical & Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
| | - Soo-Hyung Choi
- Department of Chemical Engineering, Hongik University, Seoul, 04066, Republic of Korea
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4
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Timmers EM, Fransen PM, González García Á, Schoenmakers SMC, Magana JR, Peeters JW, Tennebroek R, van Casteren I, Tuinier R, Janssen HM, Voets IK. Co-assembly of precision polyurethane ionomers reveals role of and interplay between individual components. Polym Chem 2021; 12:2891-2903. [PMID: 34046093 PMCID: PMC8129887 DOI: 10.1039/d1py00079a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/25/2021] [Indexed: 11/21/2022]
Abstract
Industrial and household products, such as paints, inks and cosmetics usually consist of mixtures of macromolecules that are disperse in composition, in size and in monomer sequence. Identifying structure-function relationships for these systems is complicated, as particular macromolecular components cannot be investigated individually. For this study, we have addressed this issue, and have synthesized a series of five sequence-defined polyurethanes (PUs): one neutral-hydrophobic, one single-charged hydrophilic, one single-charged hydrophobic and two double-charged amphiphilic PUs (one symmetric and one asymmetric). These novel precision PUs - that were prepared by using stepwise coupling-deprotection synthetic protocols - have a defined composition, size and monomer sequence, where the chosen sequences were inspired by those that are abundantly formed in the production of industrial waterborne PU dispersions. By performing dynamic light scattering experiments (DLS), self-consistent field (SCF) computations and cryogenic transmission electron microscopy (cryo-TEM), we have elucidated the behavior in aqueous solution of the individual precision PUs, as well as of binary and ternary mixtures of the PU sequences. The double-charged PU sequences ('hosts') were sufficiently amphiphilic to yield single-component micellar solutions, whereas the two more hydrophobic sequences did not micellize on their own, and gave precipitates or ill-defined larger aggregates. Both the neutral-hydrophobic PU and the hydrophilic single-charged PU were successfully incorporated in the host micelles as guests, respectively increasing and reducing the micelle radius upon incorporation. SCF computations indicated that double-charged symmetric PUs stretch whilst double-charged asymmetric PUs are expelled from the core to accommodate hydrophobic PU guests within the micelles. For the ternary mixture of the double-charged symmetric and asymmetric hosts and the neutral-hydrophobic guest we have found an improved colloidal stability, as compared to those for binary mixtures of either host and hydrophobic guest. In another ternary mixture of precision PUs, with all three components not capable of forming micelles on their own, we see that the ensemble of molecules produces stable micellar solutions. Taken together, we find that the interplay between PU-molecules in aqueous dispersions promotes the formation of stable micellar hydrocolloids.
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Affiliation(s)
- Elizabeth M Timmers
- Laboratory of Self-Organizing Soft Matter, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Laboratory of Macro-Organic Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
| | | | - Álvaro González García
- Institute for Complex Molecular Systems, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Van 't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry and Debye Institute for Nanomaterials Science, Utrecht University Padualaan 8 3584 CH Utrecht The Netherlands
| | - Sandra M C Schoenmakers
- Laboratory of Macro-Organic Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
| | - Jose Rodrigo Magana
- Laboratory of Self-Organizing Soft Matter, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Laboratory of Macro-Organic Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
| | - Joris W Peeters
- SyMO-Chem B.V. Den Dolech 2 5612 AZ Eindhoven The Netherlands
| | - Ronald Tennebroek
- DSM Resins and Functional Materials Sluisweg 12 5145 PE Waalwijk The Netherlands
| | - Ilse van Casteren
- DSM Resins and Functional Materials Sluisweg 12 5145 PE Waalwijk The Netherlands
| | - Remco Tuinier
- Institute for Complex Molecular Systems, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Van 't Hoff Laboratory for Physical and Colloid Chemistry, Department of Chemistry and Debye Institute for Nanomaterials Science, Utrecht University Padualaan 8 3584 CH Utrecht The Netherlands
| | - Henk M Janssen
- SyMO-Chem B.V. Den Dolech 2 5612 AZ Eindhoven The Netherlands
| | - Ilja K Voets
- Laboratory of Self-Organizing Soft Matter, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
- Institute for Complex Molecular Systems, Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands
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5
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Lisitsyna E, Efimov A, Depresle C, Cauchois P, Vuorimaa-Laukkanen E, Laaksonen T, Durandin N. Deciphering Multiple Critical Parameters of Polymeric Self-Assembly by Fluorescence Spectroscopy of a Single Molecular Rotor BODIPY-C12. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ekaterina Lisitsyna
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Alexander Efimov
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Clémentine Depresle
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
- INSA Rouen Normandie, 685 Avenue de l’université, 76800 Saint-Etienne-du-Rouvray, France
| | - Pierre Cauchois
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
- Ecole Nationale Supérieure de Chimie de Lille, Avenue Mendeleiev, 59652 Villeneuve-d’Ascq, France
| | - Elina Vuorimaa-Laukkanen
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
| | - Timo Laaksonen
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, FI-00014 Helsinki, Finland
| | - Nikita Durandin
- Faculty of Engineering and Natural Sciences, Tampere University, Korkeakoulunkatu 8, 33720 Tampere, Finland
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6
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Bos I, Timmerman M, Sprakel J. FRET-Based Determination of the Exchange Dynamics of Complex Coacervate Core Micelles. Macromolecules 2021; 54:398-411. [PMID: 33456072 PMCID: PMC7808214 DOI: 10.1021/acs.macromol.0c02387] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/08/2020] [Indexed: 02/07/2023]
Abstract
Complex coacervate core micelles (C3Ms) are nanoscopic structures formed by charge interactions between oppositely charged macroions and used to encapsulate a wide variety of charged (bio)molecules. In most cases, C3Ms are in a dynamic equilibrium with their surroundings. Understanding the dynamics of molecular exchange reactions is essential as this determines the rate at which their cargo is exposed to the environment. Here, we study the molecular exchange in C3Ms by making use of Förster resonance energy transfer (FRET) and derive an analytical model to relate the experimentally observed increase in FRET efficiency to the underlying macromolecular exchange rates. We show that equilibrated C3Ms have a broad distribution of exchange rates. The overall exchange rate can be strongly increased by increasing the salt concentration. In contrast, changing the unlabeled homopolymer length does not affect the exchange of the labeled homopolymers and an increase in the micelle concentration only affects the FRET increase rate at low micelle concentrations. Together, these results suggest that the exchange of these equilibrated C3Ms occurs mainly by expulsion and insertion, where the rate-limiting step is the breaking of ionic bonds to expel the chains from the core. These are important insights to further improve the encapsulation efficiency of C3Ms.
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Affiliation(s)
- Inge Bos
- Physical Chemistry and Soft
Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Marga Timmerman
- Physical Chemistry and Soft
Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Joris Sprakel
- Physical Chemistry and Soft
Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
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7
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König N, Willner L, Carlström G, Zinn T, Knudsen KD, Rise F, Topgaard D, Lund R. Spherical Micelles with Nonspherical Cores: Effect of Chain Packing on the Micellar Shape. Macromolecules 2020; 53:10686-10698. [PMID: 33335341 PMCID: PMC7735752 DOI: 10.1021/acs.macromol.0c01936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/23/2020] [Indexed: 11/30/2022]
Abstract
Self-assembly of amphiphilic polymers into micelles is an archetypical example of a "self-confined" system due to the formation of micellar cores with dimensions of a few nanometers. In this work, we investigate the chain packing and resulting shape of C n -PEOx micelles with semicrystalline cores using small/wide-angle X-ray scattering (SAXS/WAXS), contrast-variation small-angle neutron scattering (SANS), and nuclear magnetic resonance spectroscopy (NMR). Interestingly, the n-alkyl chains adopt a rotator-like conformation and pack into prolate ellipses (axial ratio ϵ ≈ 0.5) in the "crystalline" region and abruptly arrange into a more spheroidal shape (ϵ ≈ 0.7) above the melting point. We attribute the distorted spherical shape above the melting point to thermal fluctuations and intrinsic rigidity of the n-alkyl blocks. We also find evidence for a thin dehydrated PEO layer (≤1 nm) close to the micellar core. The results provide substantial insight into the interplay between crystallinity and molecular packing in confinement and the resulting overall micellar shape.
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Affiliation(s)
- Nico König
- Department
of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
- Jülich
Centre for Neutron Science (JCNS-1) and Institute of Biological Information
Processing (IBI-8), Forschungszentrum Jülich
GmbH, 52425 Jülich, Germany
| | - Lutz Willner
- Jülich
Centre for Neutron Science (JCNS-1) and Institute of Biological Information
Processing (IBI-8), Forschungszentrum Jülich
GmbH, 52425 Jülich, Germany
| | - Göran Carlström
- Centre
for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden
| | - Thomas Zinn
- ESRF
- The European Synchrotron, 38043 Grenoble, France
| | - Kenneth D. Knudsen
- Department
for Neutron Materials Characterization, Institute for Energy Technology, P.O. Box 40, 2027 Kjeller, Norway
| | - Frode Rise
- Department
of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
| | - Daniel Topgaard
- Division
of Physical Chemistry, Department of Chemistry, Lund University, Lund, Sweden
| | - Reidar Lund
- Department
of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
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8
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Guerin G, Molev G, Rupar PA, Manners I, Winnik MA. Understanding the Dissolution and Regrowth of Core-Crystalline Block Copolymer Micelles: A Scaling Approach. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c02215] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gerald Guerin
- Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Gregory Molev
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Paul A. Rupar
- Department of Chemistry, University of Alabama, Tuscaloosa, Alabama 35487, United States
| | - Ian Manners
- Department of Chemistry, University of Victoria, Victoria, British Columbia V8W 3V6, Canada
| | - Mitchell A. Winnik
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E2, Canada
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9
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Myhre S, Amann M, Willner L, Knudsen KD, Lund R. How Detergents Dissolve Polymeric Micelles: Kinetic Pathways of Hybrid Micelle Formation in SDS and Block Copolymer Mixtures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:12887-12899. [PMID: 32960616 PMCID: PMC7660944 DOI: 10.1021/acs.langmuir.0c02123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 09/22/2020] [Indexed: 06/11/2023]
Abstract
Mixtures of amphiphilic polymers and surfactants are used in a wide range of applications, e.g., pharmaceuticals, detergents, cosmetics, and drug delivery systems. Still, many questions remain on how the structure and, in particular, the kinetics of block copolymer micelles are affected in the presence of surfactants and what controls the solubilization kinetics. In this work, we have studied the stability and solubilization kinetics of block copolymer micelles upon the addition of the surfactant sodium dodecyl sulfate (SDS) using small-angle X-ray/neutron scattering. The ability of the surfactant to dissolve polymer micelles or form mixed micelles has been investigated using two types of amphiphilic polymers, poly(ethylene-alt-propylene)-poly(ethylene oxide) (PEP1-PEO20) and n-alkyl-functionalized PEO (C28-PEO5). The exchange kinetics of C28-PEO5 micelles are in the order of hours, while PEP1-PEO20 micelles are known to be frozen on a practical timescale. In this work, we show that the addition of SDS to PEP1-PEO20 provides virtually no solubilization, even after an extended period of time. However, upon adding SDS to C28-PEO5 micelles, we observe micellar dissolution and formation of mixed micelles occurring on the timescale of hours. Using a coexistence model of mixed and neat micelles, the SAXS data were analyzed to provide detailed structural parameters over time. First, we observe a fast fragmentation/fission step followed by a slow reorganization process. The latter process is essentially independent of concentration at low volume fraction but is greatly accelerated at larger concentrations. This might indicate a crossover from a predominance of molecular exchange to fusion/fission processes.
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Affiliation(s)
- Synne Myhre
- Department
of Chemistry, University of Oslo, Oslo 0315, Norway
| | - Matthias Amann
- Department
of Chemistry, University of Oslo, Oslo 0315, Norway
| | - Lutz Willner
- Jülich
Centre for Neutron Science (JCNS-1) and Institute of Biological Information
Processing (IBI-8) Forschungszentrum Jülich GmbH, Jülich 52425, Germany
| | - Kenneth D. Knudsen
- IFE, Institute
for Energy Technology, Instituttveien 18, Kjeller 2007, Norway
| | - Reidar Lund
- Department
of Chemistry, University of Oslo, Oslo 0315, Norway
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10
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König N, Willner L, Pipich V, Mahmoudi N, Lund R. Tale of Two Tails: Molecular Exchange Kinetics of Telechelic Polymer Micelles. PHYSICAL REVIEW LETTERS 2020; 124:197801. [PMID: 32469600 DOI: 10.1103/physrevlett.124.197801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Telechelic polymers contain two chain ends that are able to promote self-assembly into "flowerlike" or interconnected micellar structures. Here, we investigate the molecular exchange kinetics of such micelles using time-resolved small-angle neutron scattering. We show that the activation energies of monofunctional and telechelic chain exchange are identical. This demonstrates that the two chain ends are not simultaneously released in a single event. Instead, the results show that, contrary to regular micelles, the kinetics occurs in a multistep process involving a collision-induced single-molecule exchange mechanism where the exchange rate is directly proportional to the polymer concentration. We show that this novel mechanism can be quantitatively explained by a simple kinetic model.
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Affiliation(s)
- Nico König
- Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
- Jülich Centre for Neutron Science (JCNS) and Institute for Complex Systems (ICS), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Lutz Willner
- Jülich Centre for Neutron Science (JCNS) and Institute for Complex Systems (ICS), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Vitaliy Pipich
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, 85747 Garching, Germany
| | - Najet Mahmoudi
- ISIS-STFC, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, United Kingdom
| | - Reidar Lund
- Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
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11
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Cornel EJ, Smith GN, Rogers SE, Hallett JE, Growney DJ, Smith T, O'Hora PS, van Meurs S, Mykhaylyk OO, Armes SP. Time-resolved small-angle neutron scattering studies of the thermally-induced exchange of copolymer chains between spherical diblock copolymer nanoparticles prepared via polymerization-induced self-assembly. SOFT MATTER 2020; 16:3657-3668. [PMID: 32227048 DOI: 10.1039/c9sm02425e] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Sterically-stabilized diblock copolymer nanoparticles (a.k.a. micelles) are prepared directly in non-polar media via polymerization-induced self-assembly (PISA). More specifically, a poly(lauryl methacrylate) chain transfer agent is chain-extended via reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of methyl methacrylate (MMA) to form sterically-stabilized spheres at 20% w/w solids in n-dodecane at 90 °C. Both fully hydrogenous (PLMA39-PMMA55 and PLMA39-PMMA94) and core-deuterated (PLMA39-d8PMMA57 and PLMA39-d8PMMA96) spherical nanoparticles with mean core diameters of approximately 20 nm were prepared using this protocol. After diluting each dispersion in turn to 1.0% w/w with n-dodecane, small-angle X-ray scattering studies confirmed essentially no change in spherical nanoparticle diameter after thermal annealing at 150 °C. Time-resolved small angle neutron scattering was used to examine whether copolymer chain exchange occurs between such nanoparticles at elevated temperatures. Copolymer chain exchange for a binary mixture of PLMA39-PMMA55 and PLMA39-d8PMMA57 nanoparticles produced hybrid (mixed) cores containing both PMMA55 and d8PMMA57 blocks within 3 min at 150 °C. In contrast, a binary mixture of PLMA39-PMMA94 and PLMA39-d8PMMA96 nanoparticles required 8 min at this temperature before no further reduction in neutron scattering intensity could be observed. These observations suggest that the rate of copolymer chain exchange depends on the degree of polymerization of the core-forming block. Relatively slow copolymer chain exchange was also observed at 80 °C, which is below the Tg of the core-forming PMMA block as determined by DSC studies. These observations confirm rapid exchange of individual copolymer chains between sterically-stabilized nanoparticles at elevated temperature. The implications of these findings are briefly discussed in the context of PISA, which is a powerful technique for the synthesis of sterically-stabilized nanoparticles.
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Affiliation(s)
- Erik J Cornel
- Department of Chemistry, University of Sheffield, Brook Hill, Dainton Building, Sheffield, South Yorkshire S3 7HF, UK.
| | - Gregory N Smith
- Department of Chemistry, University of Sheffield, Brook Hill, Dainton Building, Sheffield, South Yorkshire S3 7HF, UK. and Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
| | - Sarah E Rogers
- Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, UK
| | - James E Hallett
- H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - David J Growney
- Lubrizol Ltd, Nether Lane, Hazelwood, Derbyshire DE56 4AN, UK
| | - Timothy Smith
- Lubrizol Ltd, Nether Lane, Hazelwood, Derbyshire DE56 4AN, UK
| | - Paul S O'Hora
- Lubrizol Ltd, Nether Lane, Hazelwood, Derbyshire DE56 4AN, UK
| | - Sandra van Meurs
- Department of Chemistry, University of Sheffield, Brook Hill, Dainton Building, Sheffield, South Yorkshire S3 7HF, UK.
| | - Oleksandr O Mykhaylyk
- Department of Chemistry, University of Sheffield, Brook Hill, Dainton Building, Sheffield, South Yorkshire S3 7HF, UK.
| | - Steven P Armes
- Department of Chemistry, University of Sheffield, Brook Hill, Dainton Building, Sheffield, South Yorkshire S3 7HF, UK.
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12
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Cornel EJ, O'Hora PS, Smith T, Growney DJ, Mykhaylyk OO, Armes SP. SAXS studies of the thermally-induced fusion of diblock copolymer spheres: formation of hybrid nanoparticles of intermediate size and shape. Chem Sci 2020; 11:4312-4321. [PMID: 34122889 PMCID: PMC8152590 DOI: 10.1039/d0sc00569j] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/20/2020] [Indexed: 12/19/2022] Open
Abstract
Dilute dispersions of poly(lauryl methacrylate)-poly(benzyl methacrylate) (PLMA-PBzMA) diblock copolymer spheres (a.k.a. micelles) of differing mean particle diameter were mixed and thermally annealed at 150 °C to produce spherical nanoparticles of intermediate size. The two initial dispersions were prepared via reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate in n-dodecane at 90 °C. Systematic variation of the mean degree of polymerization of the core-forming PBzMA block enabled control over the mean particle diameter: small-angle X-ray scattering (SAXS) analysis indicated that PLMA39-PBzMA97 and PLMA39-PBzMA294 formed well-defined, non-interacting spheres at 25 °C with core diameters of 21 ± 2 nm and 48 ± 5 nm, respectively. When heated separately, both types of nanoparticles regained their original dimensions during a 25-150-25 °C thermal cycle. However, the cores of the smaller nanoparticles became appreciably solvated when annealed at 150 °C, whereas the larger nanoparticles remained virtually non-solvated at this temperature. Moreover, heating caused a significant reduction in mean aggregation number for the PLMA39-PBzMA97 nanoparticles, suggesting their partial dissociation at 150 °C. Binary mixtures of PLMA39-PBzMA97 and PLMA39-PBzMA294 nanoparticles were then studied over a wide range of compositions. For example, annealing a 1.0% w/w equivolume binary mixture led to the formation of a single population of spheres of intermediate mean diameter (36 ± 4 nm). Thus we hypothesize that the individual PLMA39-PBzMA97 chains interact with the larger PLMA39-PBzMA294 nanoparticles to form the hybrid nanoparticles. Time-resolved SAXS studies confirm that the evolution in copolymer morphology occurs on relatively short time scales (within 20 min at 150 °C) and involves weakly anisotropic intermediate species. Moreover, weakly anisotropic nanoparticles can be obtained as a final copolymer morphology over a restricted range of compositions (e.g. for PLMA39-PBzMA97 volume fractions of 0.20-0.35) when heating dilute dispersions of such binary nanoparticle mixtures up to 150 °C. A mechanism involving both chain expulsion/insertion and micelle fusion/fission is proposed to account for these unexpected observations.
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Affiliation(s)
- E J Cornel
- Department of Chemistry, University of Sheffield Dainton Building, Brook Hill Sheffield South Yorkshire S3 7HF UK
| | - P S O'Hora
- Lubrizol Ltd Nether Lane, Hazelwood Derbyshire DE56 4AN UK
| | - T Smith
- Lubrizol Ltd Nether Lane, Hazelwood Derbyshire DE56 4AN UK
| | - D J Growney
- Lubrizol Ltd Nether Lane, Hazelwood Derbyshire DE56 4AN UK
| | - O O Mykhaylyk
- Department of Chemistry, University of Sheffield Dainton Building, Brook Hill Sheffield South Yorkshire S3 7HF UK
| | - S P Armes
- Department of Chemistry, University of Sheffield Dainton Building, Brook Hill Sheffield South Yorkshire S3 7HF UK
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König N, Willner L, Lund R. Structure and thermodynamics of mixed polymeric micelles with crystalline cores: tuning properties via co-assembly. SOFT MATTER 2019; 15:7777-7786. [PMID: 31482169 DOI: 10.1039/c9sm01452g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We investigate micelles formed by mixtures of n-alkyl-poly(ethylene oxide) block copolymers, Cn-PEO, with different alkyl block lengths in aqueous solution. This model system has previously been used to shed light on the interplay between exchange kinetics and crystallinity in self-assembling systems [König et al., Phys. Rev. Lett., 2019, 122, 078001]. Now we report on the structure and thermodynamics of these micelles by combining results from small-angle X-ray scattering, differential scanning calorimetry and volumetric measurements. We show that mixed micelles are formed despite the fact that length-mismatched n-alkanes of similar weights in bulk tend to demix below the crystallization temperature. Instead, the system exhibits similar properties as single-component micelles but with a modulated melting region. Interestingly, the melting point depression due to self-confinement within the micellar core can be approximately described by a generalized Gibbs-Thomson equation, similar to single-component micelles [Zinn et al. Phys. Rev. Lett., 2014, 113, 238305]. Furthermore, we find a novel scaling law for these micelles where, at least for larger n, the aggregation number scales with the third power of the length of the hydrophobic block, Nagg ∝ n3. Possibly, there might be a cross-over from the conventional Nagg ∝ n2 behaviour around n ≈ 19. However, the reason for such a transition as well as the strong n dependence remains a challenge and requires more theoretical work.
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Affiliation(s)
- Nico König
- Department of Chemistry, University of Oslo, Postboks 1033 Blindern, 0315 Oslo, Norway.
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Zhao D, Ma Y, Wang E, Lodge TP. Micellization of Binary Diblock Co-polymer Mixtures in an Ionic Liquid. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00613] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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