Photo Slideshow

Rationally Designed Complex, Hierarchical Microarchitectures

This slideshow presents images from a paper by Noorduin et al. on the emergence of self-assembling, complex mineral nanostructures from solution by manipulation of conditions in the solution such as temperature, pH, and CO 2 concentrations. The design and control of complex nano- or microstructures has practical ramifications in fields such as optics, catalysis, and electronics. Read the text by Noorduin et al. and a Perspective by E. Vlieg in the 17 May issue.

SLIDESHOW: Emerging Microarchitectures

Simply allowing CO2 from the air to enter an aqueous solution containing barium chloride and waterglass (Na2SiO3) can produce vast landscapes of microscale structures. [CREDIT: Noorduin et al. ]
Close to the top of the meniscus, we find dense fields of stems that evolve into vases and coral-shaped structures deeper in the solution. Scale bar, 100 µm. [CREDIT: Noorduin et al. ]
Hierarchical nano/microarchitectures not only offer insight into how complex forms can emerge from simple starting materials, but can also underlie coloration, wetting, mechanics, and other phenomena seen in nature. [CREDIT: James C. Weaver]
Understanding and controlling these processes could transform optics, catalysis, building construction, and many other technologies. [CREDIT: James C. Weaver]
  [CREDIT: James C. Weaver]
  [CREDIT: Noorduin et al. ]
While growing, the structures can be sculpted into desired shapes by modulating the reaction conditions. For instance, when this field of stems was developing, a simple pulse of CO2 induced the splitting of the growth fronts to form vases. [CREDIT: Noorduin et al. ]
The active growth sides of the structures can be used to control the nucleation of a new structure on an already existing one to form hierarchically complex architectures (false color). [CREDIT: Noorduin et al. ]
Because the shape development of the newly formed structure is independent of the previously grown one, arbitrary elementary shapes can be combined into desired sculptures. [CREDIT: Noorduin et al. ]
  [CREDIT: Noorduin et al. ]
  [CREDIT: James C. Weaver]
  [CREDIT: Noorduin et al. ]
  [CREDIT: Noorduin et al. ]
  [CREDIT: Noorduin et al. ]
By pinning the liquid on top of the previously formed green structures, the newly formed blue leaves can only develop in the plane of the underlying surface. [CREDIT: Noorduin et al. ]
  [CREDIT: Noorduin et al. ]
Another level of complexity can be added by combining the separate nucleation steps with the continuous sculpting during the development of the structures. [CREDIT: Noorduin et al. ]
To make these architectures, we start by growing a coral structure. [CREDIT: Noorduin et al. ]
We then grow stems inside the cavities of the coral structure. [CREDIT: Noorduin et al. ]
While the stems are growing, we sculpt them into vases. [CREDIT: Noorduin et al. ]
  [CREDIT: Noorduin et al. ]
This complex microbouquet was formed by nucleating the green stems inside the purple vases, after which the stems were opened during growth to form the blue part. [CREDIT: Noorduin et al. ]
The emergence of complex nano/microstructures is of fundamental interest, and the ability to program their form has practical ramifications in fields such as optics, catalysis, and electronics. [CREDIT: Noorduin et al. ]
  [CREDIT: Noorduin et al. ]
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