Catalysis of the Thermal Decomposition of Transition Metal Nitrate Hydrates by Poly(vinylidene difluoride).

Lasanthi Sumathirathne,William B Euler

doi:10.3390/polym13183112

Abstract

Poly(vinylidene difluoride) (PVDF) doped with transition metal nitrate hydrates are cast into thin films giving a high β-phase content. Analysis of the thermal behavior of the doped PVDF shows that the decomposition of the metal (II) nitrate hydrates to metal (II) oxides is catalyzed by the PVDF, as evidenced by reduction in the decomposition temperature by as much as 170 °C compared to the pure metal salts. In contrast, there is little to no apparent catalysis for the decomposition of the metal (III) nitrate hydrates. The FTIR spectra of the gas phase decomposition products show H2O and NO2 are the major components for both PVDF-doped material and the pure metal nitrate hydrates. A mechanism for the role of PVDF is proposed that uses the internal electric field of the ferroelectric phase to orient the nitrate ions and polarize the N–O bonds.

Highlights

Poly(vinylidene difluoride) is a well-studied semi crystalline fluoropolymer that, depending upon the phase, can be nonpolar, polar, pyroelectric, piezoelectric, or ferroelectric [1,2,3,4,5,6,7,8,9]
Zn(NO3 )2 ·6H2 O to form ZnO was significantly lower than found in the pure zinc nitrate hydrate [17]. This observation prompted us to investigate the role of Poly(vinylidene difluoride) (PVDF) in the thermal decomposition of a series of metal nitrate hydrates doped into the polymer
PVDF was doped with six different metal nitrate hydrates: Zn(II), Cu(II), Ni(II), Co(II), Fe(III), and Cr(III)

Summary

Introduction

Poly(vinylidene difluoride) is a well-studied semi crystalline fluoropolymer that, depending upon the phase, can be nonpolar, polar, pyroelectric, piezoelectric, or ferroelectric [1,2,3,4,5,6,7,8,9]. Some of the above-mentioned methods will give a high fraction of γ-phase, as well [6] It has been reported for several years that addition of dopants to PVDF leads to deposition of films with significantly modulated electromagnetic properties [3,5,7,10,11,12,13,14,15,16]. Zn(NO3 )2 ·6H2 O to form ZnO was significantly lower than found in the pure zinc nitrate hydrate [17] This observation prompted us to investigate the role of PVDF in the thermal decomposition of a series of metal nitrate hydrates doped into the polymer. The catalysis by the PVDF is effective when the products are M(II) oxides but much less so when the products are Mx Oy (x 6= y 6= 1)

Experimental

Results and Discussion

Conclusions