MAPLE deposition of PEG: PLGA thin films

We report on MAPLE deposition of thin films of PEG:PLGA blends. The films were analyzed in terms of morphology, chemical composition, wettability, and optical constants. These properties were particularly discussed in correlation with film thickness. The film thickness was increased by increasing the deposition rate (i.e., laser fluence). This method was effective for fluences up to 1 J/cm2, above which the efficiency of the deposition leveled off. Moreover, with increasing fluence above 1 J/cm2, important changes in the polymeric films were noticed: the surface roughness increased abruptly (up to ~200 nm), the polymers lost their chemical integrity and their optical constants underwent significant changes. In addition, surface wettability decreased considerably, water contact angle reaching ~90°; this was attributed to increased surface roughness and to orientation of the hydrophobic groups toward the surfaces of the films. An alternative method for obtaining thicker films was employed, by prolonging the deposition time while maintaining a constant, relatively low, deposition rate (i.e., fluence). In this case, the properties of the films were significantly less affected.