Increasing solvent polarity and addition of salts promote β‐phase poly(vinylidene fluoride) formation

Low, Yuen Kei Adarina; Tan, Li; Tan, Lay Poh; Boey, Freddy Yin Chiang; Ng, Kee Woei

doi:10.1002/app.38451

Cited by 50 publications

(37 citation statements)

References 43 publications

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“…Pristine PVDF polymer shows a degree of crystallinity ~ 45%, but for the sample prepared with NaCl, the sample shows an around 33%. Low et al [43] showed that when small amounts of NaCl are added to the PVDF solution, the salt, combined with free radicals near the crystalline surface promotes an increase of sample crystallinity [43]. However, beyond a critical concentration, the excess of salt will interact with the PVDF on the crystallite surface and promotes atoms dislocation, resulting in a decrease of the crystallinity degree of the PVDF sample (figure 5b).…”

Section: Thermal Characterizationmentioning

confidence: 99%

Strategies for the development of three dimensional scaffolds from piezoelectric poly(vinylidene fluoride)

et al. 2016

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Cell supports based on electroactive materials, that generate electrical signal variations as a response to mechanical deformations and vice-versa, are gaining increasing attention for tissue engineering applications. In particular, poly(vinylidene fluoride), PVDF, has been proven to be suitable for these applications in the form of films and two-dimensional membranes. In this work, several strategies have been implemented in order to develop PVDF three-dimensional scaffolds. Three processing methods, including solvent casting with particulate leaching and three-dimensional nylon, and freeze extraction with poly(vinyl alcohol) templates are presented in order to obtain three-dimensional scaffolds with different architectures and interconnected porosity. Further, it is shown that the scaffolds are in the electroactive β-phase and show a crystallinity degree of ~ 45%. Finally, quasi-static mechanical measurements showed that an increase of the porous size within the scaffold leads to a tensile strengths and the Young's modulus decrease, allowing tuning scaffold properties for specific tissues.

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Section: Thermal Characterizationmentioning

confidence: 99%

Strategies for the development of three dimensional scaffolds from piezoelectric poly(vinylidene fluoride)

et al. 2016

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“…Many parameters could account for the lower dielectric constant values obtained for our samples. First, the content of the β-phase in our neat PVDF could be lower than that of the PVDF these authors used [7]. Increase in the β-polymorph, with all-trans chain conformation, in PVDF would make it more polarizable when the electric field is applied, as this phase is known to be piezoelectrically active [12,40].…”

Section: Broadband Dielectric Analysismentioning

confidence: 99%

“…The electroactivity of PVDF therefore mostly depends on the β-phase content. There are different methods to increase the β-phase content, such as mechanical stretching, use of polar solvents to dissolve and re-crystallize PVDF, electrical poling, and addition of fillers [5][6][7][8]. An example is graphene oxide (GO), which increases the β-phase content via interaction of the polymer chain with the oxygen-rich groups on the surfaces of the GO layers [9,10], or cellulose, where the polymer interacts with the -OH groups [2,11].…”

Section: Introductionmentioning

confidence: 99%

Physico-Mechanical, Dielectric, and Piezoelectric Properties of PVDF Electrospun Mats Containing Silver Nanoparticles

Issa

AlMaadeed

Luyt

et al. 2017

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Poly(vinylidene fluoride) (PVDF) is a piezoelectric material with outstanding physical and mechanical properties. The piezoelectric properties depend on the β-phase content of this polymer, while the physical and mechanical properties depend on the morphology and degree of crystallinity of the material. Silver has antibacterial effects, and silver nanoparticles (Ag-NPs) have large surface areas rich in electrons. In this paper, we produced electrospun PVDF fibrous mats that contained different contents of Ag-NPs between 0% and 1.0%. The β-content in PVDF was found to increase by about 8% for Ag-NPs content of 0.4-0.6%. The electrospun fiber mats had a higher β-crystalline content, nano-pores were visible on the fiber surfaces, and the tensile strength and thermal stability were improved. Dielectric analysis indicated weak interfacial adhesion between the PVDF and AgNPs. Good piezoelectric response was observed in the electrospun fibers containing 0.4% AgNPs, which shows a good correlation between the β-crystalline phase content of the composites and its energy-harvesting application.

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“…Additives were also used to increase the β‐phase content in the final product, and each filler has its own mechanism to do that, such as graphene oxide which improves the β‐phase content through interaction between the electron‐rich oxygenated groups and the fluorine atoms, or cellulose which improves the β‐phase content by interaction between the polar hydroxyl groups and the fluorine atoms in the PVDF molecule . When polar solvents are used during PVDF processing, it can also lead to the formation of a β‐phase …”

Section: Introductionmentioning

confidence: 99%

Investigation of the physico‐mechanical properties of electrospun PVDF/cellulose (nano)fibers

Issa

Al-Maadeed

Luyt

et al. 2016

J of Applied Polymer Sci

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The electro‐activity and mechanical properties of PVDF depends mainly on the β‐phase content and degree of crystallinity. In this study, cellulose fibers were used to improve these characteristics. This could be achieved because the hydroxyl groups on cellulose would force the fluorine atoms in PVDF to be in the trans‐conformation, and the cellulose particles could act as nucleation centers. Electrospinning was used to prepare the PVDF/cellulose (nano)fibrous films, and this improved the total crystallinity and the formation of β‐crystals. However, the presence and amount of cellulose in PVDF were found to have little influence on the β‐phase content and on the total crystallinity of PVDF. Improvements in the extent of crystallinity and the β‐phase content were primarily brought about by the chain‐ and crystal orientation as a result of electrospinning. The thermal stability of PVDF in the composites slightly increased with increasing cellulose content in the composites up to 1.0 wt %, while the modulus and tensile strength significantly increased up to the same filler level. The dielectric storage permittivity also increased with increasing cellulose content, but the presence of cellulose had no influence on the dynamics of the γ‐ and β‐relaxations of the PVDF. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43594.

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Increasing solvent polarity and addition of salts promote β‐phase poly(vinylidene fluoride) formation

Cited by 50 publications

References 43 publications

Strategies for the development of three dimensional scaffolds from piezoelectric poly(vinylidene fluoride)

Strategies for the development of three dimensional scaffolds from piezoelectric poly(vinylidene fluoride)

Physico-Mechanical, Dielectric, and Piezoelectric Properties of PVDF Electrospun Mats Containing Silver Nanoparticles

Investigation of the physico‐mechanical properties of electrospun PVDF/cellulose (nano)fibers

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