ArticlesSilicone & Medical

Soft Tissue Compliant Silicones For Medical Devices

Jonathan Goff, Santy Sulaiman, Alison Philips, Max Detwiler, Barry Arkles, Gelest

ExSil silicone nanocomposites are the first in a series of ultrahigh elongation materials that achieve their unique mechanical properties via a radically different mechanism than traditional silicones. Traditional silicones rely on formation of chemically crosslinked chain networks for their elastomeric properties. ExSil nanocomposites, on the other hand, rely on mechanically interlocked polymer chains. Mechanically interlocked molecules (MIMs) include chain-linked macrocycles (catemers), as well as a variety of other topologically-linked structures, and are considered to have great potential for a new generation of “smart” soft materials. In the case of ExSil nanocomposite MIMs, flexible high molecular weight polydimethylsiloxane (PDMS) chains mechanically crosslink as a result of high degrees of entanglement and knot formation.

This distinct class of silicone elastomer exhibits surprising material properties, such as up to 5,000% stretchability with elastic recovery, the ability to resist tear failure (both initiation and propagation), self-healing/sealing behavior and intrinsically low extractables. As a group, these materials
demonstrate an ability to resist and recover from conditions that would normally result in the failure of other elastomers. ExSil was commercially introduced in 2016 as a two-component 100:1 kit formulated for maximum mechanical properties. New grades of ExSil have since been
introduced, with ranges of hardness and modulus which meet the requirements for soft-tissue implants and extracorporeal device applications.

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