One-step solution casting method for preparing polyvinylidene fluoride-based pyroelectric polymer film

A method for preparing a PVDF-based pyroelectric polymer film, comprising steps of:

• step (1):
• preparing PVDF-based pyroelectric polymer solution, comprising:
• according to application demands, selecting a suitable pyroelectric polymer material comprising PVDF and its copolymers:
• dissolving pyroelectric polymer powder or particles into a suitable solvent;
• and stirring evenly under heating to obtain a pyroelectric polymer solution;
• step (2):
• treating a substrate with a hydrophilic reagent;
• comprising:
• putting the substrate into a beaker containing the hydrophilic reagent;
• then placing the beaker into a water bath with a constant temperature for a fixed period of time;
• taking the substrate out, and then washing and drying with deionized water;
• step (3):
• preparing the PVDF-based pyroelectric polymer film;
• comprising:
• casting the pyroelectric polymer solution on the substrate which is treated by the hydrophilic reagent to form a liquid film, and curing the liquid film by controlling a casting temperature and casting time, in such a manner that the solvent in the liquid film is volatilized, thereby curing to obtain a PVDF-based pyroelectric polymer film having orderly aligned dipoles;
• wherein when the substrate (4) is treated with the hydrophilic reagent, a hydrophilic group is modified on the substrate surface;
• due to great difference in electronegativity between an oxygen atom and a hydrogen atom, the hydrogen atom of a hydroxyl group (5) on the surface of the substrate (4) is an electron-deficient site and positively charged;
• wherein the fluorine atom (1) of the PVDF-based pyroelectric polymer film is most electronegative and is negatively charged;
• the CF2 group of the polymer which is half of a dipole, is negatively charged;
• while its counterpart, the CH2 group is positively charged.