Plasma Surface Modification and Characterization of POSS-Based Nanocomposite Polymeric Thin Films

Abstract

The effect of a remote oxygen plasma on nanocomposite hybrid polymer thin films of poly[(propylmethacryl-heptaisobutyl-polyhedral oligomeric silsequioxane)-co-(methylmethacrylate)] (POSS-MA) has been examined by advancing contact angle, X-ray photoelectron spectroscopy (XPS), and variable-angle spectroscopic ellipsometry (VASE). Exposure to a 25 W remote oxygen-containing plasma was found to convert the surface of POSS-MA films from hydrophobic to hydrophilic within 20 s. The exposure time needed for this conversion to occur decreased as the O2/N2 ratio in the plasma environment increased, indicating a positive correlation between the hydrophilicity and the presence of oxygen in the plasma. Local bonding information inferred from high-resolution XPS data showed that the isobutyl bonding to the POSS moiety is replaced with oxygen as a result of plasma exposure. Finally, VASE data demonstrates that increasing the weight percent of POSS in the copolymer significantly impedes the oxygen plasma degradation of POSS-MA films. On the basis of these results, a model is presented in which the oxygen plasma removes isobutyl groups from the POSS cages and leaves a SiO2-like surface that is correspondingly more hydrophilic than the surface of the untreated samples and is more resistant to oxidation by the plasma. The ability to modify surfaces in this manner may impact the utility of this material for biomedical applications such as microfluidic devices in which the ability to control surface chemistry is critical.

Surface modification of POSS‐nanocomposite biomaterials using reactive oxygen plasma treatment for cardiovascular surgical implant applications

“…Indeed, ATR-FTIR analysis identified key chemical species on plasmatreated films where the major difference between samples was the appearance of CO, Si O Si , OH, and silanol ( SiOH) groups, confirming the presence of POSS within the polymeric matrix. This was supported by work of Augustine et al [50] using high-resolution X-ray photoelectron spectroscopy analysis of nanocomposite films after PSM. It was found that after treatment with reactive O 2 , energetic particles removed the isobutyl side chain groups from the POSS nanoparticles and replaced them with O 2 to form SiO 2 (silica) like structures, which became further resistant to oxidation during treatment [50].…”

“…This was supported by work of Augustine et al [50] using high-resolution X-ray photoelectron spectroscopy analysis of nanocomposite films after PSM. It was found that after treatment with reactive O 2 , energetic particles removed the isobutyl side chain groups from the POSS nanoparticles and replaced them with O 2 to form SiO 2 (silica) like structures, which became further resistant to oxidation during treatment [50]. A slight decrease in transmission was observed in the ATR-FTIR spectra for plasma-treated nanocomposite films with increasing power output, particularly in the O CO O and Si O Si band regions of the spectra.…”

“…Peaks at 1,245 cm −1 were assigned to O CO O vibrations from the long chain polymer backbone. The peak at 1,130 cm −1 could be assigned to POSS-containing siloxane bonding (Si O Si) [50][51][52][53][54]. Plasma-treated samples at 30 W had a similar spectrum as the untreated control with negligible variations in wavenumber.…”

Generation and Evaluation of Lunar Dust Adhesion Mitigating Materials

“…Polyhedral oligomeric silsesquioxane (POSS) molecules were deposited on polyimide film surfaces and exposure to radio frequency-generated oxygen plasma caused changes in both chemistry and topography ( Figure 1A and B). 23 POSS molecules have been demonstrated to form passivating silica-type coatings on surfaces exposed to atomic oxygen, [24][25][26] and this system was selected for investigation as a passive dust mitigation surface with the anticipation that the surface could be modified in a low Earth orbit (LEO) en route to the lunar surface. Formation of a POSS sub-monolayer resulted in reduced surface energy as evidenced by water contact angle goniometry measurements ( Figure 1C), suggesting reduced particle adhesion.…”

Synthesis and Solid-State Pyrolysis Behavior of POSS Containing Organometallic Polymer with Dicobalt Hexacarbonyl in the Side Chain

“…Due to its special cubic cage structure, it is a useful nanometer-scale building block in many polymeric materials and nanocomposites, to improve the performance of the materials [32][33][34][35][36]. Since the structure of the organometallic precursors could badly affect the morphology and properties of the yielded magnetic materials, thus, it is an effective approach to improve the performance of the obtained magnetic materials by adjusting the structure of the organometallic precursors.…”