Hydrophobic high quality ring PMOs with an extremely high stability

Abstract

Ordered mesoporous organosilicas with a high organic loading lead to a more hydrophobic character and can result in better mechanical, hydrothermal and chemical stability. In this paper, we first present an optimized synthesis method of periodic mesoporous organosilicas containing interconnected [Si(CH2)](3) rings in the presence of surfactant Brij-76. Therefore, two important synthesis parameters, which are the acid and surfactant concentration, were systematically varied. This optimization method results in highly ordered mesoporous materials with very high surface areas, high pore volumes, uniform cylindrical pores and thick walls. Further, it was found that the porosity can be controlled by the surfactant concentration without changing the pore diameter. In the second part, it is demonstrated that a post modification with HMDS or an auto-hydrophobization step leads to PMOs which are totally hydrophobic without losing their mesoporosity. In the last part, the impact of the hydrophobization on the (a) hydrothermal, (b) mechanical and (c) chemical stability is investigated. The results reveal that post modification with HMDS creates ordered materials that can withstand (a) steaming at 130 degrees C, (b) a mechanical compression of 272 MPa and (c) a treatment with 1 M NaOH for 2.5 h without any degradation of the silica network

Developing a new and versatile ordered mesoporous organosilica as a pH and temperature stable chromatographic packing material

“…7 Therefore an allyl function is added to a bridging carbon to introduce a hydrolysis free anchoring point. Although the ring PMO's based on the bare cyclic silane have previously been shown to be stable up to pH 14, this has thus far not been investigated on ring PMO's based on cyclic silanes functionalized on the methyl bridge.…”

APTES grafted ordered mesoporous silica KIT-6 for CO2 adsorption

“…The peak intensity was found higher in case of aqueous grafted adsorbents when compared to dry grafted adsorbents which confirm the higher APTES loading in aqueous grafting. The bands around $2876 cm À1 and $2930 cm À1 correspond to the symmetric and asymmetric deformation of the CH 2 groups of propyl chain present in APTES [48].…”

Mechanical Stability of Porous Low-k Dielectrics

“…At this moment, several groups reported the papers related to PMO and low-k, in which the dielectric, mechanical and hydrophobic properties were studied. [66][67][68][69] Although there is some variation in the reported k-values of PMO films, the microelectronic industry recognized that PMOs are one of the most promising ultralow-k materials to integrate in actual devices. However, still a lot of future research is required, including plasma-damage effects, adhesion, electrical characteristics and reliability.…”