The Role of Surface Charge of Nucleation Agents on the Crystallization Behavior of Poly(vinylidene fluoride)

Abstract

The effect of the surface charge of nucleation agents on the crystallization behavior of poly(vinylidene fluoride) (PVDF) has been investigated. Ion-dipole interaction between the positive surface of nucleation agents and the partially negative CF(2) dipoles of PVDF is established as a main factor for further lowering the free energy barrier for nucleation, and thus increasing significantly the crystallization kinetics. This is in contrast to the behavior observed for nucleation agents possessing either negative surface or neutral charges. Positive nucleation agents led to a remarkable increase in the crystallization temperature of PVDF (lower supercooling) as compared with that of neat PVDF. The dispersion of each type of nucleation agent is also important. The melting temperatures of nucleation agents need to be higher than the melting temperature of PVDF. The melting point and degree of crystallinity of PVDF can also be raised by using specific nucleation agents. The detailed crystallization kinetics and conformational changes of the PVDF chain have been investigated. With the addition of positive nucleation agents, the γ and β chain conformations, instead of the α phase, dominate.

Contrasting Effects of Graphene Oxide and Poly(ethylenimine) on the Polymorphism in Poly(vinylidene fluoride)

“…The increase in T c can be due to the presence of a specific interaction between -NH 2 groups of PEI and -CF 2 of PVDF Moreover, positively charged nucleating agents led to a remarkable increase in the crystallization temperature of PVDF (lower supercooling) as compared to that of neat PVDF. 46 It can be seen from Table 1 that the maximum shift in T c is ca. 6°C as compared to PVDF.…”

Crystalline polymorphism in poly(vinylidenefluoride) membranes

“…A c c e p t e d M a n u s c r i p t 45 Some advances have been performed to find out the formation mechanism of the additives on the PVDF polymorphs. It was found that the surface charge of the additives affects the polymorphs [125,126]. The interactions between the negatively charged particles and the polymer CH 2 groups, having a positive charge density, favors the nucleation of the β phase from the melt process [126].…”

“…It was found that the surface charge of the additives affects the polymorphs [125,126]. The interactions between the negatively charged particles and the polymer CH 2 groups, having a positive charge density, favors the nucleation of the β phase from the melt process [126]. It is interesting that the β PVDF nucleation was found to be dependent on the filler size but almost independent of the filler content [127].…”

Promotion and inhibition of gas hydrate formation by oxide powders

“…At present, the possibilities to control crystallization by introducing the centers of heterogeneous nucleation (nucleation promoter or inducer) are under investigation [20][21][22][23][24][25][26][27]. It is known that the activity of a promoter can depend on its crystal structure, particle size, topological and chemical inhomogeneity, and the nature of surface functional groups [28][29][30].…”