Resonant infrared pulsed laser deposition of thin biodegradable polymer films

Thin films of the biodegradable polymer poly(DL-lactide-co-glycolide) (PLGA ) were deposited using resonant infrared pulsed laser deposition (RIR-PLD). The output of a free-electron laser was focused onto a solid target of the polymer, and the films were deposited using 2.90 (resonant with O-H stretc h) and 3.40 (C-H) mum light at macropulse fluences of 7.8 and 6.7 J/cm(2), respectively. Under these conditions, a 0.5-mum thick film can be grown in less than 5 min. Film structure was determined from infrared absorbance mea surements and gel permeation chromatography (GPC). While the infrared absor bance spectrum of the films is nearly identical with that of the native pol ymer, the average molecular weight of the films is a little less than half that of the starting material. Potential strategies for defeating this mass change are discussed.