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Low Tg, strongly segregated, ABA triblock copolymers: a rheological and structural study. SOFT MATTER 2024; 20:4102-4110. [PMID: 38712674 DOI: 10.1039/d4sm00025k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
ABA triblock copolymers can form microphase separated structures where the B blocks form bridges between A domains, leading to reversible networks interesting for a variety of applications such as pressure sensitive adhesives or thermoplastic elastomers. However, a major drawback of these systems is their rapid loss of mechanical properties upon temperature increase. A potential way to circumvent this limitation would be to design ABA triblock copolymers that keep their microphase separation at high temperatures. In this paper, we report on all-soft ABA triblock copolymers having a poly(n-butyl acrylate) (PnBA) central block and poly(heptafluorobutyl acrylate) (PHFBA) outer blocks. By introducing fluorinated units, the incompatibility between the blocks is largely increased, allowing strong segregation between the block domains, which preserve the microphase separation up to high temperatures despite the low glass transition temperature of the blocks, as shown by temperature dependent SAXS measurements. We study the properties of different copolymers, with similar PHFBA volume fractions but different block lengths. Linear shear rheology measurements revealed the presence of a second, low frequency, plateau whose onset and length depend on the PnBA and PHFBA length, respectively. This plateau also persists up to higher temperatures for longer PHFBA blocks.
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Phase behavior of medium-length hydrophobically associating PEO-PPO multiblock copolymers in aqueous media. J Colloid Interface Sci 2023; 641:521-538. [PMID: 36948106 DOI: 10.1016/j.jcis.2023.03.013] [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: 12/23/2022] [Revised: 02/21/2023] [Accepted: 03/02/2023] [Indexed: 03/09/2023]
Abstract
HYPOTHESIS The micellization of block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) is driven by the dehydration of PPO at elevated temperatures. At low concentrations, a viscous solution of isolated micelles is obtained, whereas at higher concentrations, crowding of micelles results in an elastic gel. Alternating PEO-PPO multiblock copolymers are expected to exhibit different phase behavior, with altered phase boundaries and thermodynamics, as compared to PEO-PPO-PEO triblock copolymers (Pluronics®) with equal hydrophobicity, thereby proving the pivotal role of copolymer architecture and molecular weight. EXPERIMENTS Multiple characterization techniques were used to map the phase behavior as a function of temperature and concentration of PEO-PPO multiblock copolymers (ExpertGel®) in aqueous solution. These techniques include shear rheology, differential and adiabatic scanning calorimetry, isothermal titration calorimetry and light transmittance. The micellar size and topology were studied by dynamic light scattering. FINDINGS Multiblocks have lower transition temperatures and higher thermodynamic driving forces for micellization as compared to triblocks due to the presence of more than one PPO block per chain. With increasing concentration, the multiblock copolymers in solution gradually evolve into a viscoelastic network formed by soluble bridges in between micellar nodes, whereas hairy triblock micelles jam into liquid crystalline phases resembling an elastic colloidal crystal.
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Dynamics and Structure of Metallo-supramolecular Polymers Based on Short Telechelic Precursors. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00373] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Real-Time Fluctuations in Single-Molecule Rotaxane Experiments Reveal an Intermediate Weak Binding State during Shuttling. J Am Chem Soc 2021; 143:2348-2352. [PMID: 33417442 DOI: 10.1021/jacs.0c12161] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We report on the use of atomic force microscopy (AFM) to identify and characterize an intermediate state in macrocycle shuttling in a hydrogen bonded amide-based molecular shuttle. The [2]rotaxane consists of a benzylic amide macrocycle mechanically locked onto a thread that bears both fumaramide and succinic amide-ester sites, each of which can bind to the macrocycle through up to four intercomponent hydrogen bonds. Using AFM-based single-molecule force spectroscopy, we mechanically triggered the translocation of the ring between the two principal binding sites ("stations") on the axle. Equilibrium fluctuations reveal another interacting site involving the two oxygen atoms in the middle of the thread. We characterized the ring occupancy distribution over time, which confirms the intermediate in both shuttling directions. The study provides evidence of weak hydrogen bonds that are difficult to detect using other methods and shows how the composition of the thread can significantly influence the shuttling dynamics by slowing down the ring motion between the principal binding sites. More generally, the study illustrates the utility that single-molecule experiments, such as force spectroscopy, can offer for elucidating the structure and dynamics of synthetic molecular machines.
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Synthetic platform for mono-functionalised tridentate macrocycles as key precursors of mechanically-linked macromolecular systems. Org Chem Front 2021. [DOI: 10.1039/d1qo00245g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Macrocycles bearing a variety of functional groups give access to a wide range of synthetic methods for further derivatisation or preparation of more complex structures such as mechanically interlocked molecules or polymeric materials.
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Balancing Ligand Flexibility versus Rigidity for the Stepwise Self-Assembly of M 12 L 24 via M 6 L 12 Metal-Organic Cages. Chemistry 2020; 26:11960-11965. [PMID: 32378754 DOI: 10.1002/chem.202001399] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Indexed: 11/11/2022]
Abstract
Non-covalent interactions are important for directing protein folding across multiple intermediates and can even provide access to multiple stable structures with different properties and functions. Herein, we describe an approach for mimicking this behavior in the self-assembly of metal-organic cages. Two ligands, the bend angles of which are controlled by non-covalent interactions and one ligand lacking the above-mentioned interactions, were synthesized and used for self-assembly with Pd2+ . As these weak interactions are easily broken, the bend angles have a controlled flexibility giving access to M2 (L1)4 , M6 (L2)12 , and M12 (L2)24 cages. By controlling the self-assembly conditions this process can be directed in a stepwise fashion. Additionally, the multiple endohedral hydrogen-bonding sites on the ligand were found to play a role in the binding and discrimination of neutral guests.
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Tunable Interpenetrating Polymer Network Hydrogels Based on Dynamic Covalent Bonds and Metal–Ligand Bonds. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00494] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Supramolecular Superparamagnetic Nanocomposites Based on a Magnetite-Filled Unentangled Terpyridine-Functionalized Polymer. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00182] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Linear and Nonlinear Dynamic Behavior of Polymer Micellar Assemblies Connected by Metallo-Supramolecular Interactions. Polymers (Basel) 2019; 11:E1532. [PMID: 31546998 PMCID: PMC6835675 DOI: 10.3390/polym11101532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/09/2019] [Accepted: 09/15/2019] [Indexed: 02/06/2023] Open
Abstract
The linear and nonlinear rheology of associative colloidal polymer assemblies with metallo-supramolecular interactions is herein studied. Polystyrene-b-poly(tert-butylacrylate) with a terpyridine ligand at the end of the acrylate block is self-assembled into micelles in ethanol, a selective solvent for the latter block, and supramolecularly connected by complexation to divalent metal ions. The dependence of the system elasticity on polymer concentration can be semi-quantitatively understood by a geometrical packing model. For strongly associated (Ni2+, Fe2+) and sufficiently concentrated systems (15 w/v%), any given ligand end-group has a virtually 100% probability of being located in an overlapping hairy region between two micelles. By assuming a 50% probability of intermicellar crosslinks being formed, an excellent prediction of the plateau modulus was achieved and compared with the experimental results. For strongly associated but somewhat more dilute systems (12 w/v%) that still have significant overlap between hairy regions, the experimental modulus was lower than the predicted value, as the effective number of crosslinkers was further reduced along with possible density heterogeneities. The reversible destruction of the network by shear forces can be observed from the strain dependence of the storage and loss moduli. The storage moduli of the Ni2+ and Zn2+ systems at a lower concentration (12 w/v%) showed a rarely observed feature (i.e., a peak at the transition from linear to nonlinear regime). This peak disappeared at a higher concentration (15 w/v%). This behavior can be rationalized based on concentration-dependent network stretchability.
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Integrating Proteins in Layer-by-Layer Assemblies Independently of their Electrical Charge. ACS NANO 2018; 12:8372-8381. [PMID: 29965727 DOI: 10.1021/acsnano.8b03710] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Layer-by-layer (LbL) assembly is an attractive method for protein immobilization at interfaces, a much wanted step for biotechnologies and biomedicine. Integrating proteins in LbL thin films is however very challenging due to their low conformational entropy, heterogeneous spatial distribution of charges, and polyampholyte nature. Protein-polyelectrolyte complexes (PPCs) are promising building blocks for LbL construction owing to their standardized charge and polyelectrolyte (PE) corona. In this work, lysozyme was complexed with poly(styrenesulfonate) (PSS) at different ionic strengths and pH values. The PPCs size and electrical properties were investigated, and the forces driving complexation were elucidated, in the light of computations of polyelectrolyte conformation, with a view to further unravel LbL construction mechanisms. Quartz crystal microbalance and atomic force microscopy were used to monitor the integration of PPCs compared to the one of bare protein molecules in LbL assemblies, and colorimetric assays were performed to determine the protein amount in the thin films. Layers built with PPCs show higher protein contents and hydration levels. Very importantly, the results also show that LbL construction with PPCs mainly relies on standard PE-PE interactions, independent of the charge state of the protein, in contrast to classical bare protein assembly with PEs. This considerably simplifies the incorporation of proteins in multilayers, which will be beneficial for biosensing, heterogeneous biocatalysis, biotechnologies, and medical applications that require active proteins at interfaces.
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Mechanisms of Crystalloid versus Colloid Osmosis across the Peritoneal Membrane. J Am Soc Nephrol 2018; 29:1875-1886. [PMID: 29844208 DOI: 10.1681/asn.2017080828] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 04/25/2018] [Indexed: 12/27/2022] Open
Abstract
Background Osmosis drives transcapillary ultrafiltration and water removal in patients treated with peritoneal dialysis. Crystalloid osmosis, typically induced by glucose, relies on dialysate tonicity and occurs through endothelial aquaporin-1 water channels and interendothelial clefts. In contrast, the mechanisms mediating water flow driven by colloidal agents, such as icodextrin, and combinations of osmotic agents have not been evaluated.Methods We used experimental models of peritoneal dialysis in mouse and biophysical studies combined with mathematical modeling to evaluate the mechanisms of colloid versus crystalloid osmosis across the peritoneal membrane and to investigate the pathways mediating water flow generated by the glucose polymer icodextrin.ResultsIn silico modeling and in vivo studies showed that deletion of aquaporin-1 did not influence osmotic water transport induced by icodextrin but did affect that induced by crystalloid agents. Water flow induced by icodextrin was dependent upon the presence of large, colloidal fractions, with a reflection coefficient close to unity, a low diffusion capacity, and a minimal effect on dialysate osmolality. Combining crystalloid and colloid osmotic agents in the same dialysis solution strikingly enhanced water and sodium transport across the peritoneal membrane, improving ultrafiltration efficiency over that obtained with either type of agent alone.Conclusions These data cast light on the molecular mechanisms involved in colloid versus crystalloid osmosis and characterize novel osmotic agents. Dialysis solutions combining crystalloid and colloid particles may help restore fluid balance in patients treated with peritoneal dialysis.
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Photosensitizer localization in amphiphilic block copolymers controls photodynamic therapy efficacy. NANOSCALE 2017; 9:11180-11186. [PMID: 28749509 DOI: 10.1039/c7nr04403h] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Localization of the photosensitizer conjugation site in amphiphilic block copolymers is shown to have a great impact on photodynamic therapy efficiency. To this end, an asymmetric multifunctional derivative of the azadipyrromethene boron difluoride chelate (aza-BODIPY) was synthesized and inserted at specific locations in polypeptide-based rod-coil amphiphilic block copolymers. A study of the photophysical properties of the vesicle nanocarriers, obtained by self-assembly of these copolymers, as well as in vitro tests on two cancer cell lines were performed. This study aims at providing guidelines for the optimization of the synthetic design of therapeutic nanomedicines with minimal amounts of photosensitive molecules.
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Synthesis and Rheology of Bulk Metallo-Supramolecular Polymers from Telechelic Entangled Precursors. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b00646] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Influence of a Single Catenane on the Solid-State Properties of Mechanically Linked Polymers. ACS Macro Lett 2017; 6:468-472. [PMID: 35610870 DOI: 10.1021/acsmacrolett.7b00204] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report on mechanically linked polymers containing a single catenane in the middle of the chain. These polymers were synthesized by a simple procedure consisting in "clicking" polymer chains onto a functionalized palladium-templated [2]catenane, allowing the preparation of a variety of mechanically linked polymers. The flexibility of the catenane junction was modulated by removing the Pd ion from the catenane to unlock the macrocycles and increase their mobility. We show that this mobility change has a strong impact on the solid-state properties of the polymers. This is illustrated by studying the glass transition temperature of polystyrene-based polymers and the crystallization behavior of poly(ethylene oxide)-based polymers. Our study proves that a change of flexibility of a single catenane inserted into a polymer chain drastically influences the polymer behavior in the solid state.
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A photocleavable stabilizer for the preparation of PHEMA nanogels by dispersion polymerization in supercritical carbon dioxide. Polym Chem 2017. [DOI: 10.1039/c6py01633b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Synthesis of PHEMA nanogels stable in water by a scCO2 process.
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Control over the assembly and rheology of supramolecular networks via multi-responsive double hydrophilic copolymers. Polym Chem 2017. [DOI: 10.1039/c6py02143c] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
An orthogonal control over network formation and dynamics is achieved in metallo-supramolecular micellar gels via multi-responsive double hydrophilic copolymers.
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Orthogonal Control of the Dynamics of Supramolecular Gels from Heterotelechelic Associating Polymers. ACS Macro Lett 2016; 5:1364-1368. [PMID: 35651219 DOI: 10.1021/acsmacrolett.6b00831] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One of the first examples of supramolecular gels presenting independent dual dynamics is built through a combination of hydrophobic and metal-ligand interactions. The associating building block consists in a water-soluble linear polymer terminated by a short hydrophobic sticker at one end, and a coordinating moiety at the other end. The distinct supramolecular nature of these noninterfering binding motifs allows the dynamics of the hydrogels to be finely tuned in an orthogonal fashion by the application of specific stimuli. Precisely, the solvent-induced plasticization of the hydrophobic associations and the acid-promoted dissociation of the metal-ligand complexes are used to control the network dynamics. By opposition to classically encountered binary gel-sol responses, we demonstrate that the stimuli-induced transition in material properties can be gradual, provided that the material structure is well designed and strong enough.
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Abstract
An original strategy for the synthesis of diblock copolymers where the blocks are linked by a catenane junction is described. Starting from a functionalized catenane precursor, our strategy enables the preparation of a variety of copolymers by different techniques such as ROP, ATRP and CuAAC click reaction.
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How Supramolecular Assemblies Control Dynamics of Associative Polymers: Toward a General Picture. Macromolecules 2016. [DOI: 10.1021/acs.macromol.5b01535] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Correction: Catenane-based mechanically-linked block copolymers. Chem Commun (Camb) 2016; 52:3254. [DOI: 10.1039/c6cc90059c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Correction for ‘Catenane-based mechanically-linked block copolymers’ by B. Nisar Ahamed et al., Chem. Commun., 2016, DOI: 10.1039/c5cc09775d.
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Precise Control over the Rheological Behavior of Associating Stimuli-Responsive Block Copolymer Gels. Gels 2015; 1:235-255. [PMID: 30674175 PMCID: PMC6318586 DOI: 10.3390/gels1020235] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 11/20/2015] [Accepted: 11/30/2015] [Indexed: 11/17/2022] Open
Abstract
"Smart" materials have considerably evolved over the last few years for specific applications. They rely on intelligent macromolecules or (supra-)molecular motifs to adapt their structure and properties in response to external triggers. Here, a supramolecular stimuli-responsive polymer gel is constructed from heterotelechelic double hydrophilic block copolymers that incorporate thermo-responsive sequences. These macromolecular building units are synthesized via a three-step controlled radical copolymerization and then hierarchically assembled to yield coordination micellar hydrogels. The dynamic mechanical properties of this particular class of materials are studied in shear flow and finely tuned via temperature changes. Notably, rheological experiments show that structurally reinforcing the micellar network nodes leads to precise tuning of the viscoelastic response and yield behavior of the material. Hence, they constitute promising candidates for specific applications, such as mechano-sensors.
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Advances in Colloidal Assembly: The Design of Structure and Hierarchy in Two and Three Dimensions. Chem Rev 2015; 115:6265-311. [DOI: 10.1021/cr400081d] [Citation(s) in RCA: 531] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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FP554OSMOTIC WATER TRANSPORT INDUCED BY ICODEXTRIN OCCURS INDEPENDENTLY OF WATER CHANNELS AND RESEMBLES COLLOID OSMOSIS. Nephrol Dial Transplant 2015. [DOI: 10.1093/ndt/gfv180.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Controlling the melt rheology of linear entangled metallo-supramolecular polymers. SOFT MATTER 2015; 11:762-774. [PMID: 25492131 DOI: 10.1039/c4sm02319f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We study in the melt the linear viscoelastic properties of supramolecular assemblies obtained by adding different amounts of nickel ions to linear entangled poly(ethylene oxide) (PEO) building blocks end-functionalized by a terpyridine group. We first show that the elasticity of these supramolecular assemblies is mainly governed by the entanglement dynamics of the building blocks, while the supramolecular interactions delay or suppress their relaxation. By adjusting the amount of metal ions, the relaxation time as well as the level of the low-frequency plateau of these supramolecular assemblies can be controlled. In particular, the addition of metal ions above the 1:2 metal ion/terpyridine stoichiometric ratio allows secondary supramolecular interactions to appear, which are able to link the linear supramolecular assemblies and thus, lead to the reversible gelation of the system. By comparing the rheological behavior of different linear PEO samples, bearing or not functionalized chain-ends, we show that these extra supramolecular bonds are partially due to the association between the excess of metal ions and the oxygen atoms of the PEO chains. We also investigate the possible role played by the terpyridine groups in the formation of these secondary supramolecular interactions.
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Revealing the supramolecular nature of side-chain terpyridine-functionalized polymer networks. Int J Mol Sci 2015; 16:990-1007. [PMID: 25569082 PMCID: PMC4307286 DOI: 10.3390/ijms16010990] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 12/19/2014] [Indexed: 11/29/2022] Open
Abstract
Nowadays, finely controlling the mechanical properties of polymeric materials is possible by incorporating supramolecular motifs into their architecture. In this context, the synthesis of a side-chain terpyridine-functionalized poly(2-(dimethylamino)ethyl methacrylate) is reported via reversible addition-fragmentation chain transfer polymerization. By addition of transition metal ions, concentrated aqueous solutions of this polymer turn into metallo-supramolecular hydrogels whose dynamic mechanical properties are investigated by rotational rheometry. Hence, the possibility for the material to relax mechanical constrains via dissociation of transient cross-links is brought into light. In addition, the complex phenomena occurring under large oscillatory shear are interpreted in the context of transient networks.
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Double thermo-responsive hydrogels from poly(vinylcaprolactam) containing diblock and triblock copolymers. Polym Chem 2015. [DOI: 10.1039/c4py01606h] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The thermally-induced gelation and gel properties of concentrated aqueous solutions of double thermoresponsive poly(N-vinylamide)-based di- and triblock copolymers are studied by rheology.
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Synthesis and Self-Assembly of Terpyridine End-Capped Poly(N-Isopropylacrylamide)-block-Poly(2-(Dimethylamino)ethyl Methacrylate) Diblock Copolymers. Macromol Rapid Commun 2014; 36:610-5. [DOI: 10.1002/marc.201400553] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 11/02/2014] [Indexed: 12/22/2022]
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Self-assembly of a triblock terpolymer mediated by hydrogen-bonded complexes. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/pola.27471] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Controlling the Cross-Linking Density of Supramolecular Hydrogels Formed by Heterotelechelic Associating Copolymers. Macromolecules 2014. [DOI: 10.1021/ma500537t] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Thermo-responsive properties of metallo-supramolecular block copolymer micellar hydrogels. SOFT MATTER 2014; 10:3086-3092. [PMID: 24695908 DOI: 10.1039/c3sm53013b] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Metallo-supramolecular micellar hydrogels exhibiting thermo-mechanical responsiveness are prepared through the hierarchical assembly of a heterotelechelic associating copolymer. The copolymer consists of a linear thermo-sensitive water-soluble sequence terminated by a short hydrophobic sticker at one end, the other being functionalized by a chelating ligand. As the first level of assembly, the associating copolymer is dissolved in aqueous solution to yield micellar nanostructures, bearing coordinative motifs at the end of the coronal chains. The second level of assembly is achieved when transition metal ions are added to the micellar solutions, resulting in almost instantaneous gelation. The thermo-mechanical response of those materials is investigated in detail by rotational rheometry, showing abrupt changes within the temperature boundaries corresponding to the phase transition of the polymer block located in the micellar corona.
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Double thermoresponsive di- and triblock copolymers based on N-vinylcaprolactam and N-vinylpyrrolidone: synthesis and comparative study of solution behaviour. Polym Chem 2014. [DOI: 10.1039/c4py00852a] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Controlled radical polymerization produces poly(N-vinylamide)s with thermally induced multistep assembly.
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Physical consequences of a mechanically interlocked architecture: benzylic amide catenane NH stretching vibrations as sensitive probes for weakly hydrogen-bonding environments. Chemphyschem 2013; 1:97-100. [PMID: 23696287 DOI: 10.1002/1439-7641(20000915)1:2<97::aid-cphc97>3.0.co;2-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2000] [Indexed: 11/11/2022]
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Hydrogels with Dual Relaxation and Two-Step Gel–Sol Transition from Heterotelechelic Polymers. Macromolecules 2013. [DOI: 10.1021/ma401657f] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Pore-Functionalized Nanoporous Materials Derived from Block Copolymers. Macromol Rapid Commun 2013; 34:962-82. [DOI: 10.1002/marc.201300214] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 04/18/2013] [Indexed: 11/10/2022]
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One-pot controlled synthesis of double thermoresponsive N-vinylcaprolactam-based copolymers with tunable LCSTs. Polym Chem 2013. [DOI: 10.1039/c3py00134b] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Abstract
This contribution describes the synthesis and associating behavior in water of a multiresponsive amphiphilic diblock copolymer. This copolymer is composed of an hydrophobic photocleavable poly(para-methoxyphenacyl methacrylate) block (PMPMA) and a hydrophilic thermosensitive poly[(oligo ethylene glycol)methacrylate] block (POEGMA). The PMPMA-b-POEGMA copolymer forms micelles with a PMPMA core and a POEGMA corona in water. Light irradiation leads to the transformation of PMPMA into poly(methacrylic acid) (PMAA) and to the disruption of the initial micelles. The response of the accordingly obtained PMAA-b-POEGMA copolymer to pH, temperature, calcium (Ca2+), and phosphate (PO43-) ions is demonstrated.
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Functionalized nanoporous thin films from metallo-supramolecular diblock copolymers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:3018-3023. [PMID: 22235922 DOI: 10.1021/la204920b] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A polystyrene-[Ni(2+)]-poly(ethylene oxide) metallo-supramolecular block copolymer (PS-[Ni(2+)]-PEO), where -[ is a terpyridine, is used to create nanoporous thin films with free terpyridine ligands homogenously distributed on the pore walls. The PS-[Ni(2+)]-PEO block copolymer is synthesized by a two step assembly process, and is then self-assembled into a thin film in order to obtain PEO cylinders oriented perpendicularly to the film surface. The supramolecular junction is opened by exposing the film to an excess of a competing ligand, and the free PEO block is then rinsed away by a selective solvent. The presence of the terpyridines on the pore walls is evidenced by fluorescence spectroscopy after formation of a fluorescent complex with an europium salt.
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Temperature-Responsive Aqueous Micelles From Terpyridine End-Capped Poly(N-Isopropylacrylamide)-Block-Polystyrene Diblock Copolymers. Macromol Rapid Commun 2011; 33:534-9. [DOI: 10.1002/marc.201100640] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 10/17/2011] [Indexed: 11/06/2022]
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A single synthetic small molecule that generates force against a load. NATURE NANOTECHNOLOGY 2011; 6:553-557. [PMID: 21857685 DOI: 10.1038/nnano.2011.132] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/15/2011] [Indexed: 05/31/2023]
Abstract
Some biomolecules are able to generate directional forces by rectifying random thermal motions. This allows these molecular machines to perform mechanical tasks such as intracellular cargo transport or muscle contraction in plants and animals. Although some artificial molecular machines have been synthesized and used collectively to perform mechanical tasks, so far there have been no direct measurements of mechanical processes at the single-molecule level. Here we report measurements of the mechanical work performed by a synthetic molecule less than 5 nm long. We show that biased Brownian motion of the sub-molecular components in a hydrogen-bonded [2]rotaxane-a molecular ring threaded onto a molecular axle-can be harnessed to generate significant directional forces. We used the cantilever of an atomic force microscope to apply a mechanical load to the ring during single-molecule pulling-relaxing cycles. The ring was pulled along the axle, away from the thermodynamically favoured binding site, and was then found to travel back to this site against an external load of 30 pN. Using fluctuation theorems, we were able to relate measurements of the work done at the level of individual rotaxane molecules to the free-energy change as previously determined from ensemble measurements. The results show that individual rotaxanes can generate directional forces of similar magnitude to those generated by natural molecular machines.
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