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

Abstract

ARTICLEThis journal is © The Royal Society of Chemistry 2015 J. Name., 2015, 00, 1-3 | 1 The group transfer polymerization (GTP) of alkyl methacrylates has been studied using hydrosilane and tris(pentafluorophenyl)borane (B(C 6 F 5 ) 3 ) as the new initiation system. For the B(C 6 F 5 ) 3 -catalyzed polymerization of methyl methacrylate (MMA) using triethylsilane, tri-n-butylsilane (nBu 3 SiH), dimethylphenylsilane (Me 2 PhSiH), triphenylsilane, and triisopropylsilane, nBu 3 SiH and Me 2 PhSiH were suitable for producing well-defined polymers with predicted molar masses and a low polydispersity. The livingness of the GTP of MMA using Me 2 PhSiH/B(C 6 F 5 ) 3 was verified by the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) measurement of the resulting polymers, kinetic analyses, and chain extension experiments. The B(C 6 F 5 ) 3 -catalyzed GTP using Me 2 PhSiH was also applicable for other alkyl methacrylates, such as the n-propyl, n-hexyl, n-decyl, 2-ethylhexyl, iso-butyl, and cyclohexyl methacrylates. The in situ formation of the silyl ketene acetal by the 1,4-hydrosilylation of MMA was proved by the MALDI-TOF MS and 2 H NMR measurements of the polymers obtained from the B(C 6 F 5 ) 3 -catalyzed GTPs of MMA with Me 2 PhSiH or Me 2 PhSiD, which was terminated using CH 3 OH or CD 3 OD.

Organocatalyzed Group Transfer Polymerization

“…This new GTP methodology was also applicable for the polymerization of MMA, though its reactivity was lower than that of an acrylate monomer 105. Me 2 PhSiH was found to be the suitable hydrosilane and the livingness of the polymerization of MMA was confirmed by kinetic analyses, chain‐extension experiments, and MALDI‐TOF MS measurements, as already discussed above.…”

Silyl Ketene Acetals/B(C6F5)3 Lewis Pair-Catalyzed Living Group Transfer Polymerization of Renewable Cyclic Acrylic Monomers

“…Tris(pentafluorophenyl)borane, B(C 6 F 5 ) 3 , was prepared according to literature procedures. [ 57 , 58 ] Literature procedures were also employed for the preparation of the following compounds: dimethylketene methyl triethylsilyl acetal ( Et SKA) [ 49 ], dimethylketene methyl triphenylsilyl acetal Me 2 C=C(OMe)OSiPh 3 ( Ph SKA) [ 50 ], dimethylketene nethyl triisobutylsilyl acetal Me 2 C=C(OMe)OSi( i Bu) 3 ( i Bu SKA) [ 50 ],dimethylketene methyl dimethyl-phenylsilyl acetal Me 2 C=C(OMe)OSiMe 3 ( Me2Ph SKA) [ 54 ].…”

“…More recently, a tandem (FLP and LA) activation method was developed for GTP involving the in-situ generation of SKA initiators by 1,4-hydrosilylation of a methacrylate monomer. In such a process, the catalysts, such as highly electron deficient silylium cations “R 3 Si + ” [ 53 ] or strong LAs E(C 6 F 5 ) 3 (E = B, Al) [ 5 , 6 , 54 , 55 ], play dual role in both hydrosilylation (via frustrated Lewis Pair (FLP)-type activation) and activation of monomer (classical LA activation). However, such system was shown to be much less effective for E(C 6 F 5 ) 3 (E = B, Al)-catalyzed GTP at high monomer to initiator ratios [ 6 , 53 ] and ill-controlled for Al(C 6 F 5 ) 3 -catalyzed MMA polymerization.…”

Production and Polymerization of Biobased Acrylates and Analogs

“…[ 334 ] Further work by the Kakuchi and Chen groups has allowed the study of various monomers, tertiary silanes and Al(C 6 F 5 ) 3 as a strong Lewis acid. [ 335–338 ]…”