期刊
ACS APPLIED MATERIALS & INTERFACES
卷 14, 期 7, 页码 8938-8946出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.1c20938
关键词
PVDF; polymer composites; mass spectrometry; rapid heating; nanoparticles
资金
- Air Force Office of Scientific Research (AFOSR) [FA9550-21-10336]
- Defense Threat Reduction Agency Materials in Extreme Environments, MSEE-URA [HDTRA1-20-2-0001]
The interactions between nanoscale metal oxides and poly(vinylidene fluoride) at high temperature were investigated. It was found that HF gas reacts exergonically and exothermically with hydroxyl-terminated metal oxide surfaces, potentially forming stronger metal-fluorine bonds. However, not all compositions produce stable metal fluoride.
Interactions between energetic material relevant nanoscale metal oxides (SiO2, TiO2, MgO, Al2O3, CuO, Bi2O3) and poly(vinylidene fluoride) (PVDF) at high temperature were investigated by temperature-jump/time-of-flight mass spectrometry (T-jump/TOFMS) and thermogravimetric-differential scanning calorimetry (TGA-DSC). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the morphology of the compositions, while X-ray diffraction (XRD) was utilized to analyze the condensed phase crystalline species at temperatures of interest. The exergonicity and exothermicity of HF gas with hydroxyl-terminated metal oxide surfaces make HF the likely fluorine-bearing moiety and primary mode of the fluorinating reactions, where terminal OH- configurations are replaced by F- in the formation of a stronger metal-fluorine bond. However, not all compositions produce corresponding stable metal fluoride. The results show that while some of the investigated metal oxide-PVDF compositions enhance PVDF decomposition and release HF in larger quantities than PVDF, others release HF in smaller quantities than PVDF and even retard PVDF decomposition. The former compositions demonstrate exothermic, multistep mass loss modes prior to neat PVDF mass loss, and the relative intensity of HF gas increases as the temperature of the release point decreases, implying a correlation between HF release and the progression of exothermic behavior. An interplay dynamic where surface interactions both lower the onset of HF release and engage exothermically with HF gas subsequently is proposed.
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