Reversible Tethering of Polymers onto Catechol-Based Titanium Platforms

In this article, we report on the reversible tethering of end-functionalized polymers onto catechol-based titanium platforms by exploiting the reversible Diels–Alder (DA) cycloaddition reaction. For this purpose, furan and maleimide end-functionalized polymers, prepared via reversible addition–fragmentation chain transfer polymerization, were covalently grafted through a DA reaction onto reactive titanium platforms elaborated from catechol-based anchors incorporating either the furan or the maleimide moiety. As a proof of concept, a hydrophilic poly­(oligo­(ethylene glycol)­acrylate) (POEGA) and a hydrophobic poly­(2,2,2-trifluoroethyl acrylate) (PTFEA) were grafted onto titanium surfaces and subsequently detached by exploiting the thermoreversible nature of the DA reaction [i.e., retro Diels–Alder (rDA)]. These polymers were interchanged by performing a second DA reaction, thereby allowing the titanium surface wettability to be switched from hydrophobic to hydrophilic on demand. The grafting of furan/maleimide end-functionalized polymers onto functionalized (maleimide/furan, respectively) catechol-based titanium platforms and the subsequent rDA/DA sequence used for switching the titanium surface were evidenced by attenuated total reflectance–Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, and contact angle measurements.