Freestanding 3D supramolecular particle bridges: Fabrication and mechanical behavior

Freestanding hybrid particle bridges on 3D substrates were demonstrated by combining self-assembly of particles, supramolecular LbL assembly of host- and guest-functionalized glues based on dendrimers within the particle crystal, and the transfer printing technique. Flat and topographically patterned silicon substrates were cleaned by immersion in piranha solution for 15 min to form a SiO2 layer on the surface. The substrates were then sonicated in Milli-Q water and ethanol for 1 min, and dried with N2. PDMS stamps were prepared by casting a Mixture of elastomer and curing agent against a photolithographically patterned silicon master. PS-CD particles were convectively assembled into the grooves of the PDMS stamp by using a capillary-assisted deposition setup. These particle bridges were found to possess a bending modulus of 0.8 1.1 GPa, which approaches the modulus of pure PS and is one order of magnitude higher than that of the dendrimers. Failure analysis on the structure indicated linear elastic behavior and a plastic deformation upon failure.