Abstract
We present colloidal gels formed from dispersions of PEG- and PEG+DNA-coated silica nanoparticles showing structural colour. The PEG- and PEG+DNA-coated silica colloids are functionalized using exclusively covalent bonds in aqueous conditions. Both sets of colloids self-assemble into thermally-reversible colloidal gels with porosity that can be tuned by changing the colloid volume fraction, although the interaction potentials of the colloids in the two systems are different. Confocal microscopy and image analysis tools are used to characteraize the gels' microstructures. Optical reflection spectroscopy is employed to study the underlying gel nanostructure and to characterize the optical response of the gels. X-ray nanotomography is used to visualize the nanoscale phase separation between the colloid-rich gel branches and the colloid-free gel pores. These nanoparticle gels open new routes for creating structural colour where the gel structure is decoupled from the form factor of the individual colloids. This approach can be extended to create unexplored three dimensional macroscale materials with length scales spanning hundreds of nanometers, which has been difficult to achieve using other methods.
Highlights
Forming three-dimensional macroscopic materials with feature sizes on the order of hundreds of nanometers remains a challenge for many current materials processing techniques
We present a X-ray nanotomography image of the DNA-NP gel in the aqueous state showing the morphology of the gel nanostructure
We have developed colloidal gels with feature sizes of hundreds of nanometers using functionalized 30nm silica colloids
Summary
Forming three-dimensional macroscopic materials with feature sizes on the order of hundreds of nanometers remains a challenge for many current materials processing techniques. The control of the morphology of materials at this length scale is a promising approach for optimizing a device’s performance and unlocking novel device functionalities. Topdown patterning methods, such as interference lithography[1], have been successful in creating planar geometries on the macro-scale. By contrast, such as those using block copolymers, can be designed to self-assemble in three dimensions[2], but these systems are limited to feature sizes of tens of nanometers and a finite thickness of microns. In colloidal self-assembly, the attraction potentials between colloids can lead to materials with short-range order and characteristic length scales spanning tens of nanometers to tens of microns. Much of the research into DNA coated colloids (DNACCs) has focused on sensing DNA sequences[9], assembling discrete
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
