The present invention relates to a method for impregnating a filter having pores suitable for retaining particles within them that may be present in a flow of air suitable for passing through the filter, according to which the filter made up of a polymer membrane is impregnated with one or more organometallic salts by applying a treatment using supercritical CO.sub.2, the metal M of each salt being chosen from among the group of rare earths, yttrium, scandium, chromium, or a combination thereof. The invention also relates to the obtained filter and an associated method for the collection and quantitative analysis of nanoparticles.

According to one embodiment, a composition of matter includes: a first system of continuous voids arranged in a three-dimensional matrix; a second system of continuous voids arranged in the three-dimensional matrix; and a nanoporous barrier separating the first system of continuous voids and the second system of continuous voids. The first system of continuous voids and the second system of continuous voids are interwoven but independent so as to form a plurality of channels through the three-dimensional matrix. Corresponding methods for forming the composition of matter are also disclosed.

According to one embodiment, a composition of matter includes: a first system of continuous voids arranged in a three-dimensional matrix; a second system of continuous voids arranged in the three-dimensional matrix; and a nanoporous barrier separating the first system of continuous voids and the second system of continuous voids. The first system of continuous voids and the second system of continuous voids are interwoven but independent so as to form a plurality of channels through the three-dimensional matrix. Corresponding methods for forming the composition of matter are also disclosed.

Methods of fabricating complex three-dimensional structures on patterned substrates and related compositions are provided. The methods involve depositing on the substrate a block copolymer material that is mismatched to the substrate pattern, and then ordering the material to form a complex three-dimensional structure. According to various embodiments, the copolymer material mismatches the substrate pattern in that the symmetry and/or length scale of its bulk morphology differs from that of the pattern. When ordered, a balance between the physics that determines the bulk block copolymer morphology and the physics that determines the substrate surface interfacial interactions results in a thermodynamically stable complex three-dimensional film that varies in a direction perpendicular to the substrate and has a morphology that differs from its bulk morphology.