Merging of zwitterionic ROP and photoactivated thiol–yne coupling for the synthesis of polyether single-chain nanoparticles

Preparation of polyether single-chain nanoparticles (SCNPs) has remained as an elusive issue in spite of the significant interest in the synthesis of polyether derivatives with complex architectures (i.e., star-shaped, cyclic, multicyclic, and supramolecular structures). In this work, we report the facile access to polyether SCNPs by combining zwitterionic ring-opening polymerization (ZROP) and thiol–yne coupling (TYC) techniques. Linear copolymers of tetrahydrofuran (THF) and glycidyl propargyl ether (GPgE), P(GPgE-co-THF), and terpolymers of THF, GPgE, and glycidyl phenyl ether (GPE), P(THF-GPgE-GPE), having naked alkyne functional groups (10–21 mol %) were synthesized through ZROP at high content of THF in the feed. Only P(THF-GPgE-GPE) terpolymers were found to give polyether SCNPs upon photoactivated TYC reaction by working at appropriate dilution conditions (0.5 mg/mL) and using 3,6-dioxa-1,8-octane-dithiol as homobifunctional cross-linker. The different monomer sequence distribution in the copolymers when compared to that in the terpolymers was the responsible for this behavior, as revealed by in situ polymerization 13C nuclear magnetic resonance measurements. A significant reduction in intrinsic viscosity was observed upon SCNP formation. Analysis of hydrodynamic data from size exclusion chromatography with triple detection in terms of Mark–Houwink–Sakurada plots revealed that the degree of compaction increases upon increasing the alkyne content in the SCNP precursor. Polyether SCNPs were found to be noncrystalline rubbery materials at room temperature.We gratefully acknowledge support from MINECO (MAT2012-31088) and Basque Government (IT-654-13).Peer reviewe