Synthesis of syndiotactic‐rich star‐shaped poly(methyl methacrylate) by core‐first group transfer polymerization using N‐(trimethylsilyl)bis(trifluoromethanesulfonyl)imide

Abstract

AbstractThe N‐(trimethylsilyl)bis(trifluoromethanesulfonyl)imide‐catalyzed (Me3SiNTf2‐catalyzed) group transfer polymerization (GTP) of methyl methacrylate (MMA) has been studied for synthesizing stereospecific star‐shaped poly(methyl methacrylate)s (PMMAs). The catalytic property of Me3SiNTf2 for the GTP of MMA using 1‐methoxy‐1‐trimethylsilyloxy‐2‐methyl‐propene as the initiator was confirmed by a kinetic investigation and matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry measurement. The initiating efficiency (f) of Me3SiNTf2 was 0.94–1.00, which was estimated by the value of Mn(calcd)/Mn(SEC). The Me3SiNTf2‐catalyzed GTP of MMA was carried out using initiators possessing three, four, and six MTS groups (MTS3, MTS4, and MTS6, respectively) under the condition of [MMA]0/[MTS3, MTS4, or MTS6]0 = 120 at −55 °C. All the obtained PMMAs exhibited unimodal and narrow molecular weight distributions as Mw/Mns = 1.03–1.04 and the Mw(MALS)s of the 3‐, 4‐, and 6‐armed star‐shaped PMMAs (PMMA3, PMMA4, and PMMA6, respectively) were 12.9, 12.9, and 13.4 kgmol−1, respectively, which fairly agreed with the calculated Mw(calcd) values. The syndiotacticities, rrs, of PMMA3, PMMA4, and PMMA6 were in the range of 87–89%. The stereoblock synthesis of PMMA3, PMMA4, and PMMA6 was performed by the first and second polymerizations at −55 and 45 °C; the rrs of the first and second PMMA blocks were 87.0, 87.0, and 86.0% and 65.0, 65.0, and 64.0%, respectively. The glass transition temperatures (Tgs) were 118.1, 115.8, and 111.5 °C for the respective syndiotactic‐rich PMMA3, PMMA4, and PMMA6 and 111.5, 109.7, and 107.6 °C for the respective stereoblock ones. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012