Benjamin R. Lund

Hydrolytically Stable Thiol–ene Networks for Flexible Bioelectronics

Hydrolytically stable, tunable modulus polymer networks are demonstrated to survive harsh alkaline environments and offer promise for use in long-term implantable bioelectronic medicines known as electroceuticals. Todays polymer networks (such as polyimides or polysiloxanes) succeed in providing either stiff or soft substrates for bioelectronics devices; however, the capability to significantly tune the modulus of such materials is lacking. Within the space of materials with easily modified elastic moduli, thiol-ene copolymers are a subset of materials that offer a promising solution to build next generation flexible bioelectronics but have typically been susceptible to hydrolytic degradation chronically. In this inquiry, we demonstrate a materials space capable of tuning the substrate modulus and explore the mechanical behavior of such networks. Furthermore, we fabricate an array of microelectrodes that can withstand accelerated aging environments shown to destroy conventional flexible bioelectronics.

Shape Memory Polymer–Inorganic Hybrid Nanocomposites

Shape memory polymers (SMPs) have been the focus of much research over the last few decades. From the novelty of temporarily fixing a three-dimensional shape from a planar polymer sheet, to the uses that SMPs are seeing today as softening biomedical implants and self-deploying hinges, this class of smart materials has successfully been used to tackle a variety of biological, electrical, and mechanical problems. However, the properties of these networks are limited by the organic nature of the SMPs. To enhance their properties, researchers across the globe have looked into imparting the desirable properties of inorganic composite materials to these polymer networks. As the field of shape memory polymer composites began to grow, researchers quantified the unique enhancements that came at varying filler loading levels as a result of controlled material interface interactions. Specifically, the incorporation of nanofillers of various shapes and sizes leads to increased internal interfacial area relative to micro- and macrocomposites at identical loading fractions and imparts interesting mechanical, optical, electrical, thermal, and magnetic properties to these emerging nanocomposites. This new class of material, referred to in this review as shape memory polymer–inorganic nanocomposites (SMPINCs), allows a host of new interactions between the smart polymer and its surrounding environment as a result of the ability to control the internal environment of the polymer network and nanofiller. In this work, the reader is introduced to both the methods of preparing these composites and the effects the fillers have on the biological, electromagnetic, and mechanical properties of the resulting composite.