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

Abstract

The 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

Organocatalyzed Group Transfer Polymerization

“…We next examined the GTP of MMA using the isolated Lewis acid of Tf 2 NSiMe 3 itself as the catalyst 93. The polymerization of MMA in CH 2 Cl 2 at 25°C under the conditions of [MMA] 0 /[ Me SKA] 0 /[Tf 2 NSiMe 3 ] 0 = 80/1/0.05 and [MMA] 0 = 2.0 mol L −1 proceeded smoothly as expected and produced a PMMA with an M n of 8.6 kg mol −1 and an M w / M n of 1.07 within 9 h. The kinetics of the polymerization of MMA using Tf 2 NSiMe 3 also showed a first‐order relationship between the polymerization time and the monomer conversion.…”

“…Several attempts to synthesize star‐shaped polymers by the organocatalyzed GTP have been carried out by us;93,110–112 the synthetic results are summarized in Table . We first achieved the core‐first synthesis of star‐shaped polymers by the organocatalyzed GTP using star‐shaped initiators with multiple SKA groups (Scheme ) and an organocatalyst of either t ‐Bu‐P 4 or Tf 2 NSiMe 3 .…”

B(C6F5)3-catalyzed group transfer polymerization of alkyl methacrylates with dimethylphenylsilane through in situ formation of silyl ketene acetal by B(C6F5)3-catalyzed 1,4-hydrosilylation of methacrylate monomer

“…In addition, acid organocatalysts, such as triphenylmethyl tetrakis(pentafluorophenyl)borane, [18][19][20][21] (R)-3,3'-bis[3,5-bis(trifluoromethyl)phenyl]-1,1'-binaphthyl-2,2'-disulfonimide, 22 trifluoromethanesulfonimide, [23][24][25][26] N-(trimethylsilyl)triflylimide, 27,28 and 1-[bis(trifluoromethanesulfonyl)methyl]-2,3,4,5,6-pentafluorobenzene, 25,26 were suitable for the controlled/living unstable SKA. For the former issue, Taton et al reported that NHC was efficient for the synthesis of block copolymers composed of methacrylate and acrylate monomers, N,N-dimethylacrlamide, and methacrylonitrile.…”

Organic Lewis Pairs Based on Phosphine and Electrophilic Silane for the Direct and Controlled Polymerization of Methyl Methacrylate: Experimental and Theoretical Investigations

“…[49][50][51] In polymer chemistry, the ability of Me3SiNTf2 to activate (meth)acrylates monomers has recently been evidenced by Kakuchi et al in the case of the Group Transfer Polymerization of both acrylates and (meth)acrylates monomers, using a silylketeneacetal as initiator. [52][53][54] In the present study, we compare the behavior of Me3SiOTf and Me3SiNTf2 as LA's when used in conjunction with different phosphines, including P t Bu3, P n Bu3 and TTMPP as LB's. Remarkably, the peculiar combination involving TTMPP:Me3SiNTf2 in a 1:2 molar ratio allows the metal-free LPP being conducted at room temperature in toluene, providing poly(methyl methacrylate) (PMMA) chains controlled by the initial [MMA]0/[TTMPP]0 molar ratio.…”