Star-Shaped Poly(tetrahydrofuran) with Reactive End Groups: Design, MALDI-TOF Study, and Solution Behavior

Abstract

Star-shaped poly(tetrahydrofuran) (PTHF) with up to six allyl end groups was prepared by living cationic ring-opening polymerization. A functional initiation system, using allyl alcohol and trifluoromethanesulfonic anhydride, was used, followed by end-capping of the living polymer chains with the multifunctional termination agent tris(2-aminoethyl)amine. In this way, star-shaped PTHF with allyl end groups could be synthesized, with varying molecular weight (6000−20 000 g·mol-1) and number of arms (three to six). Subsequently, the terminal allyl functions were quantitatively transformed into hydroxy groups using a hydroboration procedure. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis, NMR, and size exclusion chromatography confirmed the controlled synthesis of these reactive star-shaped structures. MALDI-TOF was successfully used to determine the absolute molecular weight and purity of star-shaped polymers. They were further characterized by viscosimetry measurements, and their properties were compared to their linear analogues. For the same molecular weight, the stars had a strong reduced viscosity in solution.