Capture/release ability of thermo-responsive polymer particles

Strain engineering was used to make polymer particles that are able to reversibly alter their geometry from three dimensional tubes to two dimensional layers and consequently alter their properties upon changes in temperature. A bilayer of two dissimilar materials, one being a polymer, was deposited on a sacrificial substrate and polymer tubes were formed due to the release of the interfacial residual stress upon removal of the sacrificial substrate. The bilayer consisted of a polydimethysiloxane (PDMS) film with a thickness of several microns coated with a nanometer-thick gold (Au) film. Alternatively, SiC was used instead of Au to demonstrate that the fabrication method can be applied using any two dissimilar materials. The diameter and length of the resulting polymer tubes can be tuned through the thickness of the bilayer and the processing conditions used. The modulus and geometric characteristics of these polymer particles were also determined. Finally, the ability of using these polymer particles as delivery vesicles was demonstrated through selective capture and controllable release of a fluorescently-labelled polymer such as poly(ethylene glycol), which was adsorbed only on the Au and not the PDMS surface of the polymer particles.