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Farias-Mancilla B, Balestri A, Zhang J, Frielinghaus H, Berti D, Montis C, Destarac M, Schubert US, Guerrero-Sanchez C, Harrisson S, Lonetti B. Morphology and thermal transitions of self-assembled NIPAM-DMA copolymers in aqueous media depend on copolymer composition profile. J Colloid Interface Sci 2024; 662:99-108. [PMID: 38340518 DOI: 10.1016/j.jcis.2024.02.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 01/18/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024]
Abstract
HYPOTHESIS There is a lack of understanding of the interplay between the copolymer composition profile and thermal transition observed in aqueous solutions of N-isopropyl acrylamide (NIPAM) copolymers, as well as the correlation between this transition and the formation and structure of copolymer self-assemblies. EXPERIMENTS For this purpose, we investigated the response of five copolymers with the same molar mass and chemical composition, but with different composition profile in aqueous solution against temperature. Using complementary analytical techniques, we probed structural properties at different length scales, from the molecular scale with Nuclear Magnetic Resonance (NMR) to the colloidal scale with Dynamic Light Scattering (DLS) and Small Angle Neutron Scattering (SANS). FINDINGS NMR and SANS investigations strengthen each other and allow a clear picture of the change of copolymer solubility and related copolymer self-assembly as a function of temperature. At the molecular scale, dehydrating NIPAM units drag N,N-dimethyl acrylamide (DMA) moieties with them in a gradual collapse of the copolymer chain; this induces a morphological transition of the self-assemblies from star-like nanostructures to crew-cut micelles. Interestingly, the transition spans a temperature range which depends on the monomer distribution profile in the copolymer chain, with the asymmetric triblock copolymer specimen revealing the broadest one. We show that the broad morphological transitions associated with gradient copolymers can be mimicked and even surpassed by the use of stepwise gradient (asymmetric) copolymers, which can be more easily and reproducibly synthesized than linear gradient copolymers.
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Affiliation(s)
- Barbara Farias-Mancilla
- Laboratoire Softmat, Université de Toulouse, CNRS UMR 5623, Université Toulouse III - Paul Sabatier, France
| | - Arianna Balestri
- Department of Chemistry "Ugo Schiff", University of Florence and CSGI, Florence, Italy
| | - Junliang Zhang
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Jena, Germany; Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Jena, Germany
| | - Henrich Frielinghaus
- Forschungszentrum Jülich GmbH, Jülich Center for Neutron Science at Heinz Maier-Leibnitz Zentrum, Lichtenbergstrasse 1, 85747 Garching, Germany
| | - Debora Berti
- Department of Chemistry "Ugo Schiff", University of Florence and CSGI, Florence, Italy
| | - Costanza Montis
- Department of Chemistry "Ugo Schiff", University of Florence and CSGI, Florence, Italy
| | - Mathias Destarac
- Laboratoire Softmat, Université de Toulouse, CNRS UMR 5623, Université Toulouse III - Paul Sabatier, France
| | - Ulrich S Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Jena, Germany; Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Jena, Germany
| | - Carlos Guerrero-Sanchez
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Jena, Germany; Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Jena, Germany.
| | - Simon Harrisson
- LCPO, CNRS/Bordeaux-INP/Université de Bordeaux, Pessac, France.
| | - Barbara Lonetti
- Laboratoire Softmat, Université de Toulouse, CNRS UMR 5623, Université Toulouse III - Paul Sabatier, France.
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Lai TY, Khabaz F, Cavicchi KA. Influence of solute association on the phase behavior of 12-hydroxystearic acid/ n-alkane solutions. SOFT MATTER 2023; 19:2339-2349. [PMID: 36876897 DOI: 10.1039/d3sm00013c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The phase behavior of 12-hydroxystearic acid (12-HSA) in even-numbered alkanes ranging from octane (C8) to hexatriacontane (C36) was measured by visual observation of liquid + solid to liquid and liquid-liquid to liquid cloud points and liquid + solid to liquid + liquid transitions. In general solid phases were stabilized to low concentration and higher temperature with increasing alkane length. Liquid-liquid immiscibility was observed in larger alkanes starting with octadecane. The liquidus lines of shorter alkanes (octane to hexadecane) showing only liquid to liquid + solid transitions were fit with an attenuated associated solution model based on the Flory-Huggins lattice model assuming that 12-HSA forms a carboxylic acid dimer over all concentrations investigated. The fit results show that 12-HSA forms associated structures with degrees of association ranging from 3.7-4.5 dimers in the neat 12-HSA. At low concentrations, the 12-HSA is dissociated into dimers, however the free energy cost of dissociation stabilizes the solid phase giving a sharp knee at low concentrations. The role of 12-HSA association in its phase behavior and gelation behavior are discussed. More broadly, the importance of solute association in small molecule organogelators and its potential as a molecular design parameter similar to other component thermodynamic parameters, such as melting temperature and heat of fusion, is discussed.
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Affiliation(s)
- Tzu-Yu Lai
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH, 44325, USA.
| | - Fardin Khabaz
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH, 44325, USA.
- Department of Chemical, Biomolecular, and Corrosion Engineering, University of Akron, Akron, OH, 44325, USA
| | - Kevin A Cavicchi
- School of Polymer Science and Polymer Engineering, University of Akron, Akron, OH, 44325, USA.
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Yilmazer S, Schwaller D, Mésini PJ. Beyond Sol-Gel: Molecular Gels with Different Transitions. Gels 2023; 9:gels9040273. [PMID: 37102885 PMCID: PMC10137434 DOI: 10.3390/gels9040273] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 03/29/2023] Open
Abstract
The existence of sol–gel transitions is one of the most manifest properties of molecular gels. These transitions reflect their nature since they correspond to the association or dissociation of low weight molecules through non-covalent interactions to form the network constitutive of the gel. Most described molecular gels undergo only one gel-to-sol transition upon heating, and the reverse sol-to-gel transition upon cooling. It has been long observed that different conditions of formation could lead to gels with different morphologies, and that gels can undergo a transition from gel to crystals. However, more recent publications report molecular gels which exhibit additional transitions, for instance gel-to-gel transitions. This review surveys the molecular gels for which, in addition to sol–gel transitions, transitions of different nature have been reported: gel-to-gel transitions, gel-to-crystal transition, liquid–liquid phase separations, eutectic transformations, and synereses.
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Investigation of an Organogel by Micro-Differential Scanning Calorimetry: Quantitative Relationship between the Shapes of the Thermograms and the Phase Diagram. Gels 2021; 7:gels7030093. [PMID: 34287343 PMCID: PMC8293151 DOI: 10.3390/gels7030093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/09/2021] [Accepted: 07/11/2021] [Indexed: 12/04/2022] Open
Abstract
The phase diagrams of organogels are necessary for applications and fundamental aspects, for instance to understand their thermodynamics. Differential scanning calorimetry is one of the techniques implemented to map these diagrams. The thermograms of organogels upon heating show broad endotherms, increasing gradually to a maximum, at a temperature Tmax, and decreasing back to the baseline, sometimes 10 °C above. This broadening can lead to uncertainty in determining the molar enthalpies and the melting temperatures Tm of the gels. Herein, we have measured the thermograms of the 12-hydroxystearic acid/nitrobenzene gels for weight fractions ranging from 0.0015 to 0.04. Compared with transition temperatures measured by other techniques, the inflection points of the thermograms provide a measurement of Tm with less bias than Tmax. The phase diagram explains why the molar melting enthalpies derived from the thermograms for samples of low concentration are lower than expected. The shapes of the heat flows below the peak correlate quantitatively with the diagrams: after suitable correction and normalization, the integral curves superimpose with the phase diagram in their ascending branch and reach a plateau when the gel is fully melted. The shape of the thermograms upon cooling is also qualitatively explained within the frame of the diagrams.
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Schwaller D, Zapién-Castillo S, Carvalho A, Combet J, Collin D, Jacomine L, Kékicheff P, Heinrich B, Lamps JP, Díaz-Zavala NP, Mésini PJ. Gel-to-gel non-variant transition of an organogel caused by polymorphism from nanotubes to crystallites. SOFT MATTER 2021; 17:4386-4394. [PMID: 33908587 DOI: 10.1039/d1sm00195g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
An amide based gelator forms gels in trans-decalin. Below concentrations of 1 wt% the gels melt at temperatures varying with concentration. Above a concentration of 1 wt%, upon heating, the gel transforms into an opaque gel at an invariant temperature, and melts at higher temperature. The gel-to-gel transition is evidenced by several techniques: DSC, rheology, NMR, OM and turbidimetry. The phase diagram with the domain of the existence of both morphs was mapped by these techniques. Optical and electronic microscopy studies show that the first gel corresponds to the self-assembled nanotubes while the second gel is formed by crystalline fibers. The fibers are crystalline, as shown by the presence of Bragg peaks in the scattering curves. Both morphs correspond to a different H-bonding pattern as shown by FTIR. The first gel forms at a higher cooling rate, is metastable and transforms slowly into the second one. The second gel is stable. It forms at a low cooling rate, or by thermal annealing or aging of the first gel.
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Affiliation(s)
- Duncan Schwaller
- Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France.
| | - Samuel Zapién-Castillo
- Tecnológico Nacional de México-Instituto Tecnológico de Ciudad Madero, Centro de Investigación en Petroquímica. Prolongación Bahía de Aldair, Ave. de las Bahías, Parque de la Pequeña y Mediana Industria, 89600 Altamira, Mexico.
| | - Alain Carvalho
- Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France.
| | - Jérôme Combet
- Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France.
| | - Dominique Collin
- Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France.
| | - Leandro Jacomine
- Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France.
| | - Patrick Kékicheff
- Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France.
| | - Benoît Heinrich
- Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 CNRS-Université de Strasbourg, 23 rue du Loess, 67034 Strasbourg, France
| | - Jean-Philippe Lamps
- Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France.
| | - Nancy P Díaz-Zavala
- Tecnológico Nacional de México-Instituto Tecnológico de Ciudad Madero, Centro de Investigación en Petroquímica. Prolongación Bahía de Aldair, Ave. de las Bahías, Parque de la Pequeña y Mediana Industria, 89600 Altamira, Mexico.
| | - Philippe J Mésini
- Université de Strasbourg, CNRS, Institut Charles Sadron, 23 rue du Loess, F-67000 Strasbourg, France. and International Center for Frontier Research in Chemistry, 8 allée Gaspard Monge, 67000 Strasbourg, France
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de Vet C, Gartzia-Rivero L, Schäfer P, Raffy G, Del Guerzo A. Photocontrolled Hierarchical Self-Assembly of Anisotropic Micropatterns of Nanofibers onto Isotropic Surfaces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1906723. [PMID: 31971670 DOI: 10.1002/smll.201906723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/21/2019] [Indexed: 06/10/2023]
Abstract
Hierarchical self-assembly is achieved using a visible light triggered photoreaction. A pro-gelator, α-diketone-2,3-didecyloxyanthracene, is photoconverted into a low molecular weight gelator, 2,3-didecyloxyanthracene (DDOA), that self-assembles into nanofibers. Spatial confinement and patterns of these nanofibers onto a surface are achieved by localizing initial nucleation with a focused laser and photogenerate subsequent fiber growth with the laser or gentler wide-field irradiation. Remarkably, collective growth of nanofibers results in anisotropic micropatterns with orientation factors (OF) reaching 79%, resulting in collective emission of linearly polarized light. The OF, distance of collective growth and fiber density, are controlled by the photoirradiation conditions and the balance of interactions between DDOA aggregates and the glass surface. An unprecedented juxtaposition of orthogonally oriented nanofiber patterns on an isotropic surface is achieved with individual control of the fibers' main direction. In perspective, this photochemical method can be extended to a large variety of self-assembling molecules.
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Affiliation(s)
- Christiaan de Vet
- Univ. Bordeaux, CNRS, Bordeaux INP, Institut des Sciences Moléculaires UMR 5255, 351 Cours de la Libération, 33400, Talence, France
| | - Leire Gartzia-Rivero
- Univ. Bordeaux, CNRS, Bordeaux INP, Institut des Sciences Moléculaires UMR 5255, 351 Cours de la Libération, 33400, Talence, France
- Department of Physical Chemistry, University of the Basque Country (UPV/EHU), Apartado 644, 48080, Bilbao, Spain
| | - Philip Schäfer
- Univ. Bordeaux, CNRS, Bordeaux INP, Institut des Sciences Moléculaires UMR 5255, 351 Cours de la Libération, 33400, Talence, France
| | - Guillaume Raffy
- Univ. Bordeaux, CNRS, Bordeaux INP, Institut des Sciences Moléculaires UMR 5255, 351 Cours de la Libération, 33400, Talence, France
| | - André Del Guerzo
- Univ. Bordeaux, CNRS, Bordeaux INP, Institut des Sciences Moléculaires UMR 5255, 351 Cours de la Libération, 33400, Talence, France
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