Electrical Properties of Thiol-ene-based Shape Memory Polymers Intended for Flexible Electronics

Abstract

Thiol-ene/acrylate-based shape memory polymers (SMPs) with tunable mechanical and thermomechanical properties are promising substrate materials for flexible electronics applications. These UV-curable polymer compositions can easily be polymerized onto pre-fabricated electronic components and can be molded into desired geometries to provide a shape-changing behavior or a tunable softness. Alternatively, SMPs may be prepared as a flat substrate, and electronic circuitry may be built directly on top by thin film processing technologies. Whichever way the final structure is produced, the operation of electronic circuits will be influenced by the electrical and mechanical properties of the underlying (and sometimes also encapsulating) SMP substrate. Here, we present electronic properties, such as permittivity and resistivity of a typical SMP composition that has a low glass transition temperature (between 40 and 60 °C dependent on the curing process) in different thermomechanical states of polymer. We fabricated parallel plate capacitors from a previously reported SMP composition (fully softening (FS)-SMP) using two different curing processes, and then we determined the electrical properties of relative permittivity and resistivity below and above the glass transition temperature. Our data shows that the curing process influenced the electrical permittivity, but not the electrical resistivity. Corona-Kelvin metrology evaluated the quality of the surface of FS-SMP spun on the wafer. Overall, FS-SMP demonstrates resistivity appropriate for use as an insulating material.

The Future of Neuroscience: Flexible and Wireless Implantable Neural Electronics

“…The Voit group have worked extensively with SMPs, emphasizing thiol‐ene in their body of work, [ 214–221 ] with a specific focus on the best fabrication practices to prevent delamination and thin film stress. In one notable example, [ 222 ] combining a gold adhesion layer and iridium electrodes with a parylene layer to prevent moisture ingress, the in vitro study comparing a thiol‐ene‐based probe to a fully parylene probe showed significant reduction in the Young's modulus (over a factor of 10), and the presence of immunoglobulin at the implant site.…”

Resins for Frontal Photopolymerization: Combining Depth-Cure and Tunable Mechanical Properties

“…The versatile applications of photopolymerized materials include films, printing inks, dental composite resins, coatings, and 3D printed parts in additive manufacturing [ 1 , 2 ]. Contrary to the earlier reputation of low mechanical properties (high brittleness), high-performance photopolymers with exceptional characteristics are now produced [ 3 , 4 , 5 , 6 ]. In addition, advanced 3D printing technologies, such as stereolithography (SLA) or hot lithography and two-photon polymerization, realize highly complex geometries and ultra-smooth surfaces layer by layer [ 7 , 8 ].…”

Buckling and vibration analysis of shape memory laminated composite beams under axially heterogeneous in-plane loads in the glass transition temperature region

“…The overall mechanical properties can be enhanced with the incorporation of fiber in shape memory polymer composites (SMPC). Hence, new horizons are created for its application such as aerospace [4], electronics [5], biomedical engineering [6] and textile [7].…”