This article is the first report of the RAFT polymerisation of trifluoroethylene (TrFE). Trifluoroethylene is a rare but very important fluoromonomer, as it allows the preparation of materials endowed with...
Trifluoroethylene (TrFE) is a relatively rare fluorinated monomer mainly used in copolymerisation with vinylidene fluoride (VDF) to prepare ferroelectric materials. While the VDF homopolymerisation has been relatively well studied, that...
An approach based on the use of a macromolecular coupling agent and the aim to improve the interfacial adhesion between piezoelectric ceramics and piezoelectric polymer matrix in piezoelectric composites is presented. Poly(methyl methacrylate) (PMMA) bearing a catechol moiety was used as a macromolecular coupling agent, as it is known to be miscible to piezoelectric fluoropolymers and catechol groups can strongly bind to a large variety of surfaces. Thus, entanglement between the PMMA chains and the amorphous segments of the fluoropolymer would ensure the desired interfacial adhesion. Well-defined PMMA was synthesized via RAFT polymerization using 2-cyano-2-propyl dodecyl trithiocarbonate as a chaintransfer agent. The PMMA ω-chain end was then functionalized with a catechol group via a one-pot aminolysis/thia-Michael addition procedure using a dopamine acrylamide (DA) derivative as a Michael acceptor. The presence of the catechol moiety at the chain end of PMMA was controlled by 1 H NMR and cyclic voltammetry measurements. The resulting PMMA-DA was then grafted onto the surface of a lead-free piezoelectric ceramic film (i.e., a thin film of H 2 O 2 -activated (Bi 0.5 Na 0.5 )TiO 3 (BNT) with a large contact area). The increase of the water contact angle confirmed the efficiency of the grafting. A commercial piezoelectric copolymer P(VDF-co-TrFE) was then spin-coated onto the modified BNT surface to form a bilayer composite. The composite cross section prepared by cryofracture was examined by scanning electron microscopy and revealed that the ceramic/polymer interface of the BNT-PMMA/P(VDF-co-TrFE) bilayer composite exhibits a much better cohesion than its counterpart composite prepared from nonmodified BNT. Moreover, the grazing incidence wide-angle X-ray scattering confirmed that the copolymer crystal structure was not impacted by the presence of the PMMA-DA coupling agent. A strong piezoelectric response was locally detected by piezoresponse force microscopy. This study highlights the potential of PMMA-DA as a macromolecular coupling agent to improve the ceramic/polymer interface in piezoelectric composite materials.
This article reports the surface-initiated Reversible Addition-Fragmentation chain Transfer polymerization (SI-RAFT) of trifluoroethylene (TrFE) and vinylidene fluoride (VDF) from barium titanate nanoparticles (BTO NPs) for the preparation of piezoelectric composites....
In the past decade, the adhesive properties of catechol derivatives have inspired researchers for the design of various macromolecular architectures featuring fascinating properties and finding applications in energy storage, coatings, adhesives and biomaterials. In this work, the complexation of catechol end-functionalized polymers prepared by RAFT polymerization was investigated in aqueous media with the electron-deficient tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT 4+ ) by using UV-Vis and 1 H NMR experiments. The formation of pseudorotaxanes between the catechol end-functionalized polymers and the CBPQT 4+ ,4Cl À leads to the formation of colored guest-specific complexes displaying tunable complexation properties. In particular, we demonstrated that the thermo-responsiveness i.e. the lower critical solution temperature (LCST) of the catechol end-functionalized poly(NIPAM) could be used as a simple and convenient tool to disrupt the complexation with CBPQT 4+ ; 4Cl À resulting in the disappearance of the characteristic color of the Catechol/BB complex while releasing the cyclophane in the aqueous solution. Furthermore, these supramolecular host/guest assemblies could be disrupted, on demand, by the addition of a competitive Naphthalene derivative leading to the appearance of the characteristic purple color of Naphthalene/CBPQT 4+ complexes. These results pave the way for the design of a new generation of stimuli responsive materials with control properties.catechol end-functionalized polymers, CBPQT 4+ , host-guest complexation, thermoresponsive polymers
| INTRODUCTIONNature is a fascinating source of inspiration for stimulating research in materials science. Indeed, recent progress in the adhesion mechanism of marine mussels 1 has led to the emergence of a new generation of materials mimicking the properties of these natural systems and finding various applications in coatings, 2 adhesives 3 and biomaterials. 4 In
A major challenge in materials science is dynamically adjusting material properties using sensors and control systems. This contribution develops a new approach using a self‐oscillating copolymer to autonomously change material surface properties in response to environmental changes. A redox‐sensitive terpolymer of N‐isopropylacrylamide (NIPAM), dimethylacrylamide (DMAc), and an iron‐based comonomer ([(phen)2(phen‐5‐yl‐acrylamide)FeII](PF6)2) is synthesized via Reversible Addition‐Fragmentation Chain Transfer (RAFT) polymerization, catalyzing an oscillating redox reaction (Belousov‐Zhabotinsky, BZ). The terpolymer oscillates from soluble to insoluble around 35 °C based on the iron's oxidation state. A catechol unit is incorporated to enhance versatility, enabling grafting onto different surfaces. Optimal BZ reagent concentrations are explored for maximum oscillation amplitude and frequency. By selecting a working temperature between redox transition points, the copolymer's oscillation from coil to globular conformation is observed due to redox oscillations. The self‐oscillating copolymer is grafted onto an ultrafiltration membrane, where conformational changes cause variations in pore size, leading to rapid negative flux peaks that disrupt the flux and reduce membrane fouling during protein filtration. This study highlights self‐oscillating polymers' ability to impart dynamic properties to inert materials, paving the way for smart materials with self‐regulating properties to adapt to changing conditions.
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