A “Green” Stirring Plasma Functionalization Strategy for Controllable Oxygen-Containing Functional Groups on Octa-Methyl POSS Microstructure

Abstract

The distinctive cage-like structure of polyhedral oligomeric silsesquioxane (POSS) materials makes them highly effective fillers in composite membranes for separation applications. However, realizing their full potential in the application often requires specific surface functionalization with various groups. However, this requirement remains challenging owing to the limitations of wet-chemistry approaches, which frequently result in the generation of hazardous chemical by-products. In this paper, a “green” stirring plasma strategy is presented for the functionalization of octa-methyl POSS sub-micron particles into designable oxygen-containing functional groups using a low-pressure oxygen plasma from combined continuous wave and pulsed (CW+P) modes. Plasma from oxygen gas with CW mode offers highly oxygen-reactive species to continuously etch and activate the surface of the POSS. The resulting pulsed plasma assists in grafting more reactive oxygen species onto the active methyl groups of the POSS to form specific oxygen-containing functional groups including hydroxyl and carboxyl. A precise control of nearly one hydroxyl or one carboxyl group at the corner of the cage structure of the POSS is demonstrated, without damaging the core. Therefore, the plasma process discussed in this work is suggested by the authors as controllable fundamental research for the surface functionalization of sub-micron particles, promoting a more environmentally friendly pathway for the preparation of designable fillers.

Degradation of Stains from Metal Surfaces Using a DBD Plasma Microreactor

“…Considering that large plasma power lacks competition in terms of economic efficiency, the plasma discharge power was fixed at 11.3 W. On the other hand, new absorption peaks are observed in the range of 900–1000 cm −1 , which are attributed to the generation of oxygen-containing groups. Among them, the most apparent one located at around 950 cm −1 is assigned to O–H bending and should be caused by the dissociation of water vapor to introduce hydroxyl groups on metal surfaces [ 21 ].…”