Laser Ablative Patterning of Copoly(imide siloxane)s Generating Superhydrophobic Surfaces

Abstract

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.

Generation and Evaluation of Lunar Dust Adhesion Mitigating Materials

“…Copolyimide systems containing butadiene, butadiene acrylonitrile, and siloxane components were investigated (Scheme 2). 13 These materials were prepared by the reaction of difunctional amine-terminated SMAs with aromatic diamine and dianhydride monomers to generate a polyamide acid intermediate. Films were cast on plate glass using a doctor blade, dried to tack-free in a forced air chamber, and thermally imidized in a nitrogen oven at a maximum temperature of 250°C.…”

“…13,29,30 Laser ablative patterning was achieved using an Avia frequency-tripled Nd:YAG laser (7W,  = 355 nm). After evaluating a series of surface patterns, a cross-hatch pattern was found to be the most effective for generation of low surface energy materials.…”

“…To minimize these issues, novel materials and related technologies need to be developed that passively and actively mitigate lunar dust adhesion. [13][14][15][16] Additionally, techniques to assess the efficacy of mitigation strategies need to be developed. This presentation describes the research efforts at NASA Langley Research Center's Advanced Materials and Processing Branch to address both the generation of materials with intrinsic lunar dust adhesion resistance, and the development of techniques to evaluate the performance of these materials.…”

Laser ablation of block copolymers with hydrogen-bonded azobenzene derivatives

“…The interaction of high energy lasers with polymers can result in ablation of polymers at irradiated areas [1][2][3][4][5][6][7][8][9][10][11]. Laser ablation is a quick and efficient method to fabricate microstructures and devices on polymers because structures can be generated by a single laser pulse at a time scale of nanosecond or even shorter [1,[3][4][5]10,11].…”

“…Laser ablation is a quick and efficient method to fabricate microstructures and devices on polymers because structures can be generated by a single laser pulse at a time scale of nanosecond or even shorter [1,[3][4][5]10,11]. Ablated structures on polymers show many applications, such as superhydrophobic surfaces [6], multichip modules [7], distributed feedback lasers [4], inkjet printer nozzles [8], and diffractive optical elements [5].…”