Vacuum-dried flexible hydrophobic aerogels using bridged methylsiloxane as reinforcement: performance regulation with alkylorthosilicate or alkyltrimethoxysilane co-precursors

Aerogels prepared by the co-precursor method show good flexibility.

Obtaining Hydrophobic Aerogels of Unbleached Cellulose Nanofibers of the Species Eucalyptus sp. and Pinus elliottii

The use of natural fibers from renewable and biodegradable sources in oleophilic sorbents, such as cellulose, has become an interesting alternative due to their excellent properties and sustainability. In addition to that, the low density of the aerogels obtained from cellulose is favorable for their use as sorbents. In this context, the objective of this study is to develop hydrophobic aerogels of unbleached cellulose nanofibers of the Eucalyptus sp. and Pinus elliottii. Cellulose samples were submitted to mechanical fibrillation to obtain cellulose nanofiber suspensions, followed by a chemical treatment with methyltrimethoxysilane and dried by freeze-drying to prepare the aerogels. The aerogels presented hydrophobic and oleophilic characteristics, including a water contact angle of 134°, sorption capacities in a heterogeneous medium of above 21.0 g·g−1, and oil removal efficiency greater than 88.5%. The Pinus elliottii nanofiber aerogels showed higher compressive strength when compared to the nanofiber aerogels of Eucalyptus sp.

Preparation of transparent monolithic methylsilsesquioxane (MSQ) aerogels via ambient pressure drying

Transparent monolithic MSQ aerogels were prepared by an ambient pressure drying method. The obtained hydrophobic aerogels showed good stability to various aggressive environments.