研究目的
To study the molecular interaction between carbonyl group and fluorinated monomer units of PVDF by a combination of isothermal microcalorimetry and semi-empirical quantum modeling.
研究成果
The study revealed strong binding between PVDF copolymers and carbonyl-containing solvents, characterized by large exothermic effects. The binding center has a macrocyclic structure involving H-bonds, with the strongest being between carbonyl oxygen and methylene hydrogen of vinylidene fluoride copolymer. The findings are consistent with previous reports on PVDF solutions, blends, and composites.
研究不足
The study was performed in vacuo at 0 K, and its results cannot be directly compared to the calorimetry data. The crystallinity of PVDF was avoided by using copolymers, which may not fully represent the interactions in pure PVDF.
1:Experimental Design and Method Selection:
The study combined microcalorimetry and quantum chemistry simulation to investigate H-bond formation among fluoropolymers and carbonyl solvents.
2:Sample Selection and Data Sources:
Two copolymers, poly(vinylidene fluoride-co-hexafluoropropylene) and poly(vinylidene fluoride-co-chlorotrifluoroethylene), were used. Solvents included toluene, chloroform, isopropanol, cyclohexanone, acetone, and ethyl acetate.
3:List of Experimental Equipment and Materials:
Microcalorimeter SETARAM C80, DSC131 for glass transition temperature measurement, and quantum mechanics packages HyperChem
4:7, MOPAC 21, and CAChe 5 for molecular modeling. Experimental Procedures and Operational Workflow:
The enthalpy of dissolution and dilution was measured at 25°C. Quantum chemistry calculations were performed to model the interaction between vinylidene fluoride tetramer and carbonyl solvents.
5:Data Analysis Methods:
The enthalpy of mixing was calculated and Flory-Huggins interaction parameter was evaluated. Quantum chemistry methods were used to analyze the heat of formation of complexes.
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