Synthesis of α-, ω-, and α,ω-End-Functionalized Poly(n-butyl acrylate)s by Organocatalytic Group Transfer Polymerization Using Functional Initiator and Terminator

The alpha-functionalized (hydroxyl, ethynyl, vinyl, and norbornenyl), omega-functionalized (ethynyl, vinyl, hydroxyl, and bromo), and alpha,omega-functionalized polyacrylates were precisely synthesized by the N-(trimethylsily)bis-(trifluoroethanesulfonyl)imide (Me3SiNTf2)-catalyzed group transfer polymerization (GTP) of n-butyl acrylate (nBA). The alpha-functionalization and omega-functionalization were carried out using the functional triisopropylsilyl ketene acetal as the initiator (initiation approach) and 2-phenyl acrylate derivatives as the terminator (termination approach) for the organocatalytic GTP, respectively. All the polymerizations precisely occurred and produced well-defined end-functionalized poly(n-butyl acrylate)s which had predictable molecular weights and narrow molecular weight distributions. High-molecular-weight polyacrylates were easily synthesized using both approaches. In addition, the alpha,omega-functionalized (hetero)telechelic polyacrylates were synthesized by the combination of the initiation and termination approaches. The structure of the obtained polyacrylates and degree of functionalization were confirmed by the H-1 NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS) measurements. The spectra of the H-1 NMR and MALDI-TOF MS showed that the end-functionalization quantitatively proceeded without any side reactions.