Esterification Process Induced by UV Irradiation of Shellac thin Films Deposited by Matrix Assisted Pulsed Laser Evaporation

In this work we report on the deposition of UV resistant shellac thin films by matrix assisted pulsed laser evaporation (MAPLE). The films obtained starting from a solution of 1-2 wt% shellac in methanol were very smooth and their chemical structure was preserved after the laser transfer. Upon short exposure time (u to 60 min), UV irradiation did not induce significant modifications in the films composition and surface appearance, while upon increasing the irradiation time (240 min) an esterification process of shellac can be observed.