Laser ablative patterning of copoly(imide siloxane)s generating superhydrophobic surfaces

Low surface energy copoly(imide siloxane)s were generated via condensation polymerization reactions. The generated materials were characterized spectroscopically, thermally, mechanically, and via contact angle goniometry. The decrease in tensile modulus and opaque appearance of copoly(imide siloxane) films indicated phase segregation in the bulk. Preferential surface partitioning of the siloxane moieties was verified by X-ray photoelectron spectroscopy (XPS) and increased advancing water contact angle values (theta(A)). Pristine copoly(imide siloxane) surfaces typically exhibited theta(A) values of 111 degrees and sliding angles from 27 degrees to >60 degrees. The surface properties of these copoly(imide siloxane) films were further altered using laser ablation patterning (frequency-tripled Nd:YAG laser, 355 nm). Laser-etched square pillar arrays (25 microm pillars with 25 microm interspaces) changed theta(A) by up to 64 degrees. Theta(A) values approaching 175 degrees and sliding angles from 1 degree to 15 degrees were observed. ATR-IR spectroscopy and XPS indicated polymer chain scission reactions occurred as a result of laser ablation. Initial particle adhesion studies revealed that the copoly(imide siloxane)s outperformed the corresponding homopolyimides and that laser ablation patterning further enhanced this result.