Catechol End-Functionalized Polylactide by Organocatalyzed Ring-Opening Polymerization

There is a great interest in incorporating catechol moieties into polymers in a controlled manner due to their interesting properties, such as the promotion of adhesion, redox activity or bioactivity. One possibility is to incorporate the catechol as end-group in a polymer chain using a functional initiator by means of controlled polymerization strategies. Nevertheless, the instability of catechol moieties under oxygen and basic pH requires tedious protection and deprotection steps to perform the polymerization in a controlled fashion. In the present work, we explore the organocatalyzed synthesis of catechol end-functional, semi-telechelic polylactide (PLLA) using non-protected dopamine, catechol molecule containing a primary amine, as initiator. NMR and SEC-IR results showed that in the presence of a weak organic base such as triethylamine, the ring-opening polymerization (ROP) of lactide takes place in a controlled manner without need of protecting the cathechol units. To further confirm the end-group fidelity the catechol containing PLLA was characterized by Cyclic Voltammetry and MALDI-TOF confirming the absence of side reaction during the polymerization. In order to exploit the potential of catechol moieties, catechol end-group of PLLA was oxidized to quinone and further reacted with aliphatic amines. In addition, we also confirmed the ability of catechol functionalized PLLA to reduce metal ions to metal nanoparticles to obtain well distributed silver nanoparticles. It is expected that this new route of preparing catechol-PLLA polymers without protection will increase the accessibility of catechol containing biodegradable polymers by ROP.This work was supported by Basque Government (GV/EJ) Department of Education (IT-927-16), The European Commission support through the project SUSPOL-EJD 64267 and the Gobierno Vasco/Eusko Jaurlaritza (IT 999-16 and IT-618-13). Haritz Sardon gratefully acknowledges financial support from MINECO through project SUSPOL and FDI 16507. Christophe Detrembleur thanks the "Fonds de la Recherche Scientifique" (FRS-FNRS) and the Belgian Science Policy in the frame of the Interuniversity Attraction Poles Program (P7/05)-Functional Supramolecular Systems (FS2) for financial supports. Christophe Detrembleur is Research Director by the FRS-FNRS. Nerea Sadaba is thankful for the predoctoral fellowship to POLYMAT Fundazioa-Basque Center for Macromolecular Design and Engineering