Sequential infiltration
synthesis (SIS) into poly(styrene)-
block
-maltoheptaose
(PS-
b
-MH) block copolymer
using vapors of trimethyl aluminum and water was used to prepare nanostructured
surface layers. Prior to the infiltration, the PS-
b
-MH had been self-assembled into 12 nm pattern periodicity. Scanning
electron microscopy indicated that horizontal alumina-like cylinders
of 4.9 nm diameter were formed after eight infiltration cycles, while
vertical cylinders were 1.3 nm larger. Using homopolymer hydroxyl-terminated
poly(styrene) (PS–OH) and MH films, specular neutron reflectometry
revealed a preferential reaction of precursors in the MH compared
to PS–OH. The infiltration depth into the maltoheptaose homopolymer
film was found to be 2.0 nm after the first couple of cycles. It reached
2.5 nm after eight infiltration cycles, and the alumina incorporation
within this infiltrated layer corresponded to 23 vol % Al
2
O
3
. The alumina-like material, resulting from PS-
b
-MH infiltration, was used as an etch mask to transfer
the sub-10 nm pattern into the underlying silicon substrate, to an
aspect ratio of approximately 2:1. These results demonstrate the potential
of exploiting SIS into carbohydrate-based polymers for nanofabrication
and high pattern density applications, such as transistor devices.
The colours of insects serve important visual functions in aiding mate recognition, camouflage and warning. The display of insects is usually static, as cuticle coloration does not (or hardly) change during the lifespan of a mature imago form. Here, we describe a case of humidity-dependent, brilliant coloration in the green forester moth,
Adscita statices
. We show, by employing spectroscopic and ultrastructural methods, that the moth's colour results from the interference of incident light with an unusual hydrophilic melanized-chitin multilayer present in the wing scales. Humidity changes in the environment affect the multilayer properties, causing a significant shift of the green-peaking reflectance in the dry state to a rusty colour when damp, resulting in the strong colour change between day and dusk or dawn.
Here we synthesized DIBMA copolymers with well-defined sizes and with a strictly alternating sequence of diisobutylene and maleic acid. The various copolymer fractions were tested on model membranes and biological membranes. This work sheds light on how copolymer parameters define membrane activity and properties of native nanodiscs. [1] Knowles, T.
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