Shape memory polymers can memorize and recover their permanent shapes after being programmed to hold strain levels up to a few hundred percent. While the behavior of these materials has been well investigated at the macro-scale, efforts on understanding of the shape memory characteristics at smaller lengths scale are limited. In this work, we present systematic work investigating the shape memory behaviors of crosslinked polymer micro and nanoparticles. The controlled programming of these spherical particles into highly deformed temporary shapes was achieved with nanoimprint lithography. Our study shows that the recovery behaviors of these particles depend on the degree of programming, recovery temperature, particle size, as well as confinement and contact adhesion of the substrates. Furthermore, the recovery of these particles can be constrained with a thin metal capping layer, which leads to generation of hierarchical wrinkling structures on the recovered particles. The detailed wrinkling morphologies are influenced and thereby tunable by controlling programed deformation and size of the particles, as well as metal film thickness. The work thus provides a unique approach to creating smart Janus particles with smooth, dielectric surfaces on one side and wrinkling, conductive structures on the other.

Shape memorizing micro and nano polymer particles

249th National Meeting (2015)

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