Preparation And Properties Of Gelatin Film Modified By Dicarboxylic Acid Crosslinker

In this paper,two active ester crosslinker were prepared and applied to graft and modify gelatin.In the preaence of 1-?3-dimethylaminopropyl?-3-ethylcarbodiimide hydrochloride?EDC?,furan dicarboxylic acid?FDCA?and ethylenediaminetetraacetic anhydride?EDTAD?functionalized microcrystalline cellulose?MCC?were reacted with N-Hydroxy succinimide?NHS?to obtain the crosslinkers FDCA-NHS and MCC-EDTAD-NHS?MEN?.The structure,properties and applications of modified gelatin by the two cross-linkers were investigated.The cross-linker NHS-FDCA was successfully prepared by esterification reaction,and then the amidation reaction occurred between NHS-FDCA and gelatin solution.The structure and properties of the gelatin before and after modification were studied.Successful preparation of the crosslinker was confirmed by 1H NMR and FTIR spectroscopy.The residual primary amine content and the intrinsic viscosity measurements of modified gelatin solution showed that with the increase of NHS-FDCA dosage,the content of residual primary amine groups decreased,and the intrinsic viscosity increased oppositively.Compared with the blank gelatin film,the surface of the modified gelatin film was homogeneous and smooth,also,the thermal stability was obviously improved,the maximum decomposition temperature reached290 ^oC.Degradation experiments in buffer solution indicated that the crosslinked gelatin film showed the better biocompatibility,which widened its application in food packaging materials,such as candy packaging.The reaction conditions were optimized:?(mol_?NHS-FDCA?/mol_?-NH2?)=1.5,reaction temperature was 45 ^oC and the reaction time was 12 h.Cellulose-based macromolecular active ester crosslinker MEN was successfully synthesized and used to crosslink modify gelatin?membrane?.Compared with the control gelatin film,the thermal decomposition temperature of the modified composite film was significantly increased to 350 ^oC,which was higher than that of the original gelatin film by about 30 ^oC.The mechanical test results showed that the elongation at break of the modified gelatin film increased and the elastic modulus decreased obviously,that is,the mechanical properties of gelatin film after modification were improved,the elasticity enhanced and it was not brittle.In addition,the introduction of crosslinker MEN boosted the hydrophobic properties of the gelatin film,also,with the increase of crosslinker amount,the anti-biodegradability of the gelatin composite film increased,the water absorption swelling and light resistance performance were improved significantly,the light opacity was enhanced correspondingly.The preparation of macromolecule cross-linker MEN enriched the existing EDC/NHS cross-linking system.The unique gelatin film material with advanced properties broke up the limitation of blending modification method for gelatin with macromolecule and broadened its application as novel sustained-release material in food,medicine and agriculture etc.