Method of preparing a biodegradable film

A method of preparing a biodegradable film comprising:

• coating a soluble supporting solution on a substrate to form a soluble supporting layer on the substrate, wherein a material of the soluble supporting solution includes glucose, fructose, galactose, saccharose, maltose, lactose, corn syrup, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl hydroxyethylcellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, starch, chitosan, chitin, polyvinyl alcohol or their combinations;
• coating a prepolymer solution on the soluble supporting layer to obtain a cross-linkable laminate, the cross-linkable laminate comprising the substrate, the soluble supporting layer and the prepolymer solution in a bottom-up sequence;
• pre-drying the cross-linkable laminate to dry the prepolymer solution into a prepolymer layer, so as to obtain a dried cross-linkable laminate, the prepolymer layer containing a prepolymer;
• subjecting the prepolymer in the dried cross-linkable laminate to a crosslinking reaction to obtain a cross-linked laminate, wherein the cross-linked laminate contains the substrate, the soluble supporting layer and the biodegradable film, the biodegradable film is formed by the crosslinking reaction of the prepolymer, and the crosslinking reaction is performed under an anoxic condition to obtain the cross-linked laminate, and the anoxic condition is flowed with gas of nitrogen, argon, helium, neon, krypton, xenon, radon, carbon dioxide or their combinations;
• and
• releasing the biodegradable film from the substrate of the cross-linked laminate by water washing or peeling.