| mgr inż. Karolina Stępniak |
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Ostatnie publikacje
| 1. | Grzywacz H., Jarząbek D.M., Pietrzyk-Thel P., Stępniak K., Roszkiewicz-Walczuk A., Dera W.J., Low-content MWCNTs–PVDF composites for nanoscale actuation: Crystalline tailoring and in-situ electro-mechanical analysis using hybrid AFM–Sawyer-Tower system, Carbon, ISSN: 0008-6223, DOI: 10.1016/j.carbon.2025.120738, Vol.245, No.120738, pp.1-15, 2025 Streszczenie: In this study, we present an innovative strategy for tailoring the crystalline structure and enhancing the functional properties of poly(vinylidene fluoride) (PVDF) composites reinforced with ultra-low concentrations (0.05–0.50 wt%) of multi-walled carbon nanotubes (MWCNTs). To promote the formation of the electroactive β-phase-critical for piezoelectric and electrostrictive responses-ultrasonic energy was applied during solution preparation. This approach enables significant phase transformation without high-temperature annealing or mechanical stretching, achieving over 84 % β-phase content. Beyond material synthesis, we introduce a custom-designed, in-situ experimental platform that combines an atomic force microscope (AFM) with a Sawyer-Tower electric circuit. This hybrid system allows for simultaneous, real-time measurement of electric field, electric displacement, and normal mechanical strain, enabling direct and quantitative insight into the nanoscale electromechanical coupling phenomena in the composites. Our results show that films containing up to 0.30 wt% MWCNTs exhibit enhanced and nearly hysteresis-free electrostrictive and piezoelectric behavior, making them suitable for precision nanoscale actuator applications with displacement ranges up to ∼28 nm. At higher MWCNT concentrations, increased electrical conductivity and strain hysteresis were observed, broadening the functional potential of these materials toward energy harvesting, charge storage or switching devices. The study integrates structural, electrical and electromechanical analyses with phenomenological modeling of AC/DC conductivity and band structure evolution, providing a comprehensive understanding of structure–property–function relationships. The proposed methodology offers a scalable route toward the design and calibration of multifunctional PVDF-based composites for next-generation positioning, sensing and transduction systems Słowa kluczowe: PVDF, MWCNT, Crystalline phase, Conductivity, Piezoelectric effect, Electrostriction, AFM Afiliacje autorów:
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