Development of Low Temperature Activatable Aryl Azide Adhesion Promoters as Versatile Surface Modifiers.

An innovative approach for the immobilization of polymeric films is the use of bifunctional compounds called adhesion promoters, that create a stable chemical "bridge" between materials, allowing for versatile and permanent surface modification. To connect coating materials that lack reactive groups, the "bridge" forming adhesion promoter needs a highly reactive group that can insert in otherwise unreactive chemical bonds. Activatable perfluoro-aryl azides are commonly used to achieve this, with the limitation that their thermal activation is constrained to elevated temperatures-typically far above 100 °C-and photolytic activation is often unfeasible due to geometry or opaque materials. To overcome this limitation, we designed and synthesized three small organic molecules based on substituted aryl azides with the aim of lowering the activation temperature that restricts the use of existing aryl azides. We demonstrate both computationally via density functional theory (DFT) calculations and experimentally that the activation temperature of an aryl azide can be tuned by varying its substituents, giving access to mild activation temperatures (below 100 °C). The most reactive compound was the ο,ο-difluoro substituted