Poly(vinylidene fluoride) PVDF is a semi-crystalline fluoropolymer that attracted researchers' attention more than a decade ago due to its remarkable properties, such as mechanical strength, thermal stability, chemical resistance, good processability, and excellent aging resistance. Due to these excellent properties, PVDF is applied in many applications such as membranes and filtration, biomedical applications, drug delivery, batteries, energy generation, energy storage, sensors, actuators, and energy harvesting applications.
The dissertation was inspired by PVDF’s outstanding properties and applications. First of all, the effect of chain topology of on the crystallization and polymorphism between linear and star PVDF homopolymers were studied. Well-defined linear and stars PVDF homopolymers architectures were synthesized by reversible addition−fragmentation chain transfer (RAFT) polymerization. The non-isothermal crystallization study showed an increase in the amount of ferroelectric β-phase with respect to the paraelectric α-phase as the number of arms in the PVDF stars increases. This finding is explained by the increased topological complexity in the stars of several arms, which leads to the preferential formation of the less thermodynamically stable ferroelectric β-phase. Moreover, the isothermal crystallization kinetics of the PVDF stars was faster than the linear PVDF as a result of their speedier nucleation.
Secondly, we report the synthesis of poly(n-isopropylacrylamide)-b-poly(vinylidene fluoride) (PNIPAM-b-PVDF), amphiphilic block copolymers with linear and star architectures by RAFT sequential living polymerization. Due to the presence of a lower critical solution temperature (LCST) for PNIPAM (coil-globule transition around 32 °C), the synthesized PNIPAM-b-PVDF block copolymers have thermo-responsive behavior, therefore, potential application in the fabrication of thermo-responsive membranes. All fabricated membranes by nonsolvent-induced phase separation (NIPS) method exhibited thermo-responsive behavior with water permeability and PEG rejection experiments. Moreover, the several heating-cooling cycles showed that the thermal-responsive behavior of these membranes are reversible and stable.
Finally, a suggested potential future work is given to synthesize other PVDF-based block copolymers via sequential living polymerizations.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/685932 |
| Date | 24 November 2022 |
| Creators | Algarni, Fatimah |
| Contributors | Hadjichristidis, Nikos, Physical Science and Engineering (PSE) Division, Nunes, Suzana Pereira, Cavallo, Luigi, Ameduri, Bruno |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2023-11-27, At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation will become available to the public after the expiration of the embargo on 2023-11-27. |
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