Bio-Macromolecular Surface Coatings for Autohesive, Transparent, Elastomeric Foils

Thin materials made from elastomeric polymers such as polydimethylsiloxane (PDMS) and polyurethane (PU) can be both, compliant and resilient. Their mechanical robustness and flexibility will make them great candidates for applications in the human body where space is limited and repeated deformations occur. Nonetheless, current medical applications of elastomeric foil-like products are mainly restricted to inflatable balloon parts of stents or intubation tubes. Here, a key limiting factor is the autohesive behavior of those foils, that is, their propensity to stick to themselves. This property impedes handling and processing and can also interfere with the designated tasks of such foils. To mitigate this undesired behavior, different bio-macromolecular coatings are applied here and assess their influence on the autohesive behavior, flexibility, and transparency of the materials. A non-covalent, dopamine-assisted coating approach is compared to a covalent coating strategy employing carbodiimide chemistry and investigated both, anionic and cationic macromolecules as top layers. The results show that especially the carbodiimide-mediated mucin coating can efficiently suppress the autohesive behavior of the foils while maintaining the flexibility and transparency of the material. Thus, such coatings can not only broaden the medical application range of foil-based elastomeric devices but may also prove beneficial for applications in soft robotics.