Controllable modification of the BaTiO3 nanoparticles using SI-ATRP approach and impact on the vibration sensing capabilities of their PVDF-based composites

In this contribution the ceramic nanoparticles, BaTiO3 (BT), were successfully and controllably coated with two monomers, poly(butyl acrylate) (PBA) and poly(methyl methacrylate) (PMMA) using SI-ATRP approach. The presence of the polymers on the surface was investigated using FTIR and TGA techniques. The molecular weight and polydispersity index were calculated from the gel permeation chromatography, while monomer conversion was confirmed using nuclear magnetic resonance. Both methods provide clear statement that controlled radical polymerization was successful. The surface of the neat BT, BT-PBA and BT-PMMA nanoparticles was investigated using BET analysis and using contact angle. The nanoparticles were mixed with poly(vinylidene fluoride) (PVDF) using micro compounder. The compatibility of the nanoparticles and PVDF matrix was evaluated investigation of the viscoelastic properties using dynamic mechanical analyzer. The contribution of the enhanced compatibility between the nanofiller and matrix was elucidated by electrical response to vibration testing. Finally, it will be presented how the SI-ATRP modification of BT nanoparticles with PBA and PMMA influence the capability for vibration sensing applications. © 2021 NANOCON Conference Proceedings - International Conference on Nanomaterials. All rights reserved.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: RP/CPS/2020/003; Grantová Agentura České Republiky, GA ČR: 19-17457

PVDF/PVDF-TRFE blends loaded with BaTiO3: from processing to performance testing

Concerns surrounding the limited supply of fossil fuels have been the subject of much debate. As of promising solutions, polymers like poly(vinylidene fluoride) (PVDF) have gained attention due to their ability to generate electrical energy from the waste mechanical vibrations. The energy harvesting and vibration sensing potential of PVDF is however limited due to its low content of electroactive β-phase, which has to be increased by indirect post-processing. Recently, a synergistic effect was found in PVDF directly blended with its trifluoroethylene copolymer (PVDF-TrFE) due to strong interfacial polarization. In this study, we aim to further increment the piezoelectric performance of PVDF/PVDF-TrFE blends by incorporating a small amount of BaTiO3 nanocrystals via a facile and scalable processing route. The β-phase content was monitored using FTIR and XRD. Melt rheology experiments showed that co-blending of PVDF-TrFE as well as the addition of BaTiO3 slightly increased melt viscosity and complex modulus. Despite that, rheological data suggested that developed formulations can be processed by conventional techniques intended for a large-scale production. More importantly, PVDF/PVDF-TrFE binary blends supplemented with BaTiO3 are expected to exhibit superior d33 compared to conventional neat blends, which could make them highly promising for modern energy harvesting and sensor-related applications. © 2021 NANOCON Conference Proceedings - International Conference on Nanomaterials. All rights reserved.RP/CPS/2020/003, RP/CPS/2020/006; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR: 19-17457

The Impact of Including Carbonyl Iron Particles on the Melt Electrowriting Process

Melt electrowriting, a high-resolution additive manufacturing technique, is used in this study to process a magnetic polymer-based blend for the first time. Carbonyl iron (CI) particles homogenously distribute into poly(vinylidene fluoride) (PVDF) melts to result in well-defined, highly porous structures or scaffolds comprised of fibers ranging from 30 to 50 mu m in diameter. This study observes that CI particle incorporation is possible up to 30 wt% without nozzle clogging, albeit that the highest concentration results in heterogeneous fiber morphologies. In contrast, the direct writing of homogeneous PVDF fibers with up to 15 wt% CI is possible. The fibers can be readily displaced using magnets at concentrations of 1 wt% and above. Combined with good viability of L929 CC1 cells using Live/Dead imaging on scaffolds for all CI concentrations indicates that these formulations have potential for the usage in stimuli-responsive applications such as 4D printing.Peer reviewe

Comparative study of pvdf sheets and their sensitivity to mechanical vibrations: The role of dimensions, molecular weight, stretching and poling

This paper is focused on the comparative study of the vibration sensing capabilities of poly(vinylidene fluoride) (PVDF) sheets. The main parameters such as molecular weight, initial sample thickness, stretching and poling were systematically applied, and their impact on sensing behavior was examined. The mechanical properties of prepared sheets were investigated via tensile testing on the samples with various initial thicknesses. The transformation of the α-phase to the electro-active β-phase was analyzed using FTIR after applying stretching and poling procedures as crucial post-processing techniques. As a complementary method, the XRD was applied, and it confirmed the crystallinity data resulting from the FTIR analysis. The highest degree of phase transformation was found in the PVDF sheet with a moderate molecular weight (Mw of 275 kDa) after being subjected to the highest axial elongation (500%); in this case, the β-phase content reached approximately 90%. Finally, the vibration sensing capability was systematically determined, and all the mentioned processing/molecular parameters were taken into consideration. The whole range of the elongations (from 50 to 500%) applied on the PVDF sheets with an Mw of 180 and 275 kDa and an initial thickness of 0.5 mm appeared to be sufficient for vibration sensing purposes, showing a d33 piezoelectric charge coefficient from 7 pC N−1 to 9.9 pC N−1 . In terms of the d33, the PVDF sheets were suitable regardless of their Mw only after applying the elongation of 500%. Among all the investigated samples, those with an initial thickness of 1.0 mm did not seem to be suitable for vibration sensing purposes. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Czech Science FoundationGrant Agency of the Czech Republic [19-17457S]RP/CPS/2020/003; Horizon 2020 Framework Programme, H2020; European Cooperation in Science and Technology, COST: CA18203; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Grantová Agentura České Republiky, GA ČR: 19-17457

Atom transfer radical polymerization of pyrrole-bearing methacrylate for production of carbonyl iron particles with conducting shell for enhanced electromagnetic hielding

The conducting polymer poly(2-(1H-pyrrole-1-yl)ethyl methacrylate (PPEMA) was synthesized by conventional atom transfer radical polymerization for the first time from free as well as surface-bonded alkyl bromide initiator. When grafted from the surface of carbonyl iron (CI) a substantial conducting shell on the magnetic core was obtained. Synthesis of the monomer as well as its polymer was confirmed using proton spectrum nuclear magnetic resonance (H-1 NMR). Polymers with various molar masses and low dispersity showed the variability of this approach, providing a system with a tailorable structure and brush-like morphology. Successful grafting from the CI surface was elucidate by transmission electron microscopy and Fourier-transform infrared spectroscopy. Very importantly, thanks to the targeted nanometer-scale shell thickness of the PPEMA coating, the magnetization properties of the particles were negligibly affected, as confirmed using vibration sample magnetometry. Smart elastomers (SE) consisting of bare CI or CI grafted with PPEMA chains (CI-PPEMA) and silicone elastomer were prepared and dynamic mechanical properties as well as interference shielding ones were investigated. It was found that short polymer chains grafted to the CI particles exhibited the plasticizing effect, which might be interesting from the magnetorheological point of view, and more interestingly, in comparison to the neat CI-based sample, it provided enhanced electromagnetic shielding of nearly 30 dB in thickness of 500 mu m. Thus, SE containing the newly synthesized CI-PPEMA hybrid particles also exhibited considerably enhanced damping factor and proper mechanical performance, which make the material highly promising from various practical application points of view.Ministry of Education, Youth and Sports of the Czech Republic-DKRVO [RP/CPS/2022/003]; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2021/003]; Integrated Infrastructure Operational Programme - ERDF [313021T081]; Slovak Research and Development Agency [APVV-19-0338]; Slovak Grant Agency VEGA [2/0129/19]; Qatar University Grant [QUCG-CAM-22/23-504]RP/CPS/2022/003; Slovenská Akadémia Vied, SAV: 313021T081; Tomas Bata University in Zlin, TBU: IGA/CPS/2021/003; Qatar University, QU: QUCG-CAM-22/23-504; Agentúra na Podporu Výskumu a Vývoja, APVV: APVV-19-0338; Vedecká Grantová Agentúra MŠVVaŠ SR a SAV, VEGA: 2/0129/19; European Regional Development Fund, ERD

Polylactide-based networks containing dynamic tetraphenylethane groups for 3D printed repairable and reprocessable constructs

This study aims to synthesize sustainable polylactide (PLA) materials, specifically polyester-urethanes based on PLAs with various molecular weights, to enhance thermal shape stability through crosslinking and enable reprocessing due to the presence of a new type of dynamic/reversible covalent bonds in the polymer structure. PLA-based networks containing dynamic bonds were prepared by coupling (using hexamethylene diisocyanate) PLA star polymers bearing four terminal -OH groups with a low molecular weight diol containing groups that undergo reversible dissociation upon heating. The PLAs prepolymers of two molecular weights (Mn = 3700 and 7800 g/mol) were synthesized via cationic polymerization of D,L-lactide to obtain the networks of different crosslinking densities. The low molecular weight diol, containing a tetraphenylethane moiety (TPE) with an easy dissociating bond, was synthesized from 4-hydroxybenzophenone. Networks without reversible bonds, containing 1,1′-bi-2-naphthol (binol) instead of TPE units, were also prepared as a reference. All networks were analyzed by Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis and were subjected to tensile tests. The tensile strength of all networks was in the range of 22–45 MPa. The elongations at break of networks differed based on the type of used low molecular weight diol, with values in the range of 28–67% for TPE-containing networks, in comparison with 10% for reference samples. Rheological studies of these materials were performed at a higher temperature (150 °C) to clearly demonstrate the behavioral differences between networks with and without “reversible” bonds. Only the networks with TPE groups were able to recover their previous strength after strain deformation at 150 °C in four subsequent cycles. Moreover, it was shown that networks with reversible groups were repairable and 3D printable at temperatures as low as 150 °C, while those containing non-reversible bonds did not exhibit such capability.DKRVO, (RP/CPS/2022/003); Tomas Bata University in Zlin, TBU, (IGA/CPS/2021/004); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Narodowe Centrum Nauki, NCN, (2018/31/B/ST8/01969)National Science Centre, Poland [2018/31/B/ST8/01969]; Ministry of Education, Youth and Sports of the Czech Republic - DKRVO [RP/CPS/2022/003]; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2021/004

The Impact of Including Carbonyl Iron Particles on the Melt Electrowriting Process

Melt electrowriting, a high-resolution additive manufacturing technique, is used in this study to process a magnetic polymer-based blend for the first time. Carbonyl iron (CI) particles homogenously distribute into poly(vinylidene fluoride) (PVDF) melts to result in well-defined, highly porous structures or scaffolds comprised of fibers ranging from 30 to 50 mu m in diameter. This study observes that CI particle incorporation is possible up to 30 wt% without nozzle clogging, albeit that the highest concentration results in heterogeneous fiber morphologies. In contrast, the direct writing of homogeneous PVDF fibers with up to 15 wt% CI is possible. The fibers can be readily displaced using magnets at concentrations of 1 wt% and above. Combined with good viability of L929 CC1 cells using Live/Dead imaging on scaffolds for all CI concentrations indicates that these formulations have potential for the usage in stimuli-responsive applications such as 4D printing.Peer reviewe