Controlled radical polymerization of a trialkylsilyl methacrylate by reversible addition–fragmentation chain transfer polymerization

Abstract

The reversible addition-fragmentation chain transfer (RAFT) polymerization of a hydrolyzable monomer (tert-butyldimethylsilyl methacrylate) with cumyl dithiobenzoate and 2-cyanoprop-2-yl dithiobenzoate as chain-transfer agents was studied in toluene solutions at 70 8C. The resulting homopolymers had low polydispersity (polydispersity index < 1.3) up to 96% monomer conversion with molecular weights at high conversions close to the theoretical prediction. The profiles of the number-average molecular weight versus the conversion revealed controlled polymerization features with chain-transfer constants expected between 1.0 and 10. A series of poly (tert-butyldimethylsilyl methacrylate)s were synthesized over the molecular weight range of 1.0 Â 10 4 to 3.0 Â 10 4 , as determined by size exclusion chromatography. As strong differences of hydrodynamic volumes in tetrahydrofuran between poly(methyl methacrylate), polystyrene standards, and poly(tert-butyldimethylsilyl methacrylate) were observed, true molecular weights were obtained from a light scattering detector equipped in a triple-detector size exclusion chromatograph. The Mark-Houwink-Sakurada parameters for poly(tert-butyldimethylsilyl methacrylate) were assessed to obtain directly true molecular weight values from size exclusion chromatography with universal calibration. In addition, a RAFT agent efficiency above 94% was confirmed at high conversions by both light scattering detection and 1 H NMR spectroscopy. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5680-5689, 2005

Experimental Requirements for an Efficient Control of Free‐Radical Polymerizations via the Reversible Addition‐Fragmentation Chain Transfer (RAFT) Process

“…Finally, a difference in the relative comonomer consumption rates between a RAFT and a conventional free radical copolymerization does not necessarily imply a modification of the reactivity ratio values-defined as the ratio between the homo-and the cross-propagation rate coefficients, k aa /k ab and k bb /k ba -since they only depend on [9,13,41,67,68,72,74,80,107,[110][111][112]114,119,121,129,133] a) [135,137,138,140,141] BMA [110,148] a) [140] b) [72,151] EHMA b) [150,151] LMA [133,154] BzMA [107] TFEMA [154] HEMA [157] a) [67,72,110,158] c) [159] NMAS [76] HEMA-TMS [162] TRIS-MA [163] tBDMSMA [164] DMAEMA [67] AEMA [136] GMA c) [171] MMAm …”

Poly(trialkylsilyl methacrylate)s: A family of hydrolysable polymers with tuneable erosion profiles

“…2-phenylprop-2-yl dithiobenzoate (Cumyl dithiobenzoate: CDB) was synthesised as described in the literature [16]. Tert-butyldimethylsilyl methacrylate (SiMA) was prepared according to the literature [15]. A tri-butyltin (TBT) based copolymer containing 68% of methyl methacrylate and 32% of hydrolysable tri-butyltin methacrylate monomer units was used as a well-known systems with a controlled erosion (Cutinox 1120 Ò , 50 wt.% in toluene, from ACIMA).…”

“…Compared with other controlled radical polymerization (CRP) techniques, the RAFT polymerization is suitable with a wide range of monomers and solvents. This method, which uses thiocarbonyl-thio compounds as chain transfer agents (CTA), leads to the synthesis of (meth)acrylic-based polymers with controlled molecular weight and narrow molecular weight distribution (PDI < 1.2) [14,15]. The molar proportion of the silylated monomer units and the molecular weight of copolymers have been varied to achieve desirable film formation and erosion properties of coatings.…”

Toward New Materials Prepared via the RAFT Process: From Drug Delivery to Optoelectronics?

“…The presence of trialkylsilyl esters as pendant groups, subject to hydrolysis, led to water-soluble polymers and induced the decrease of the coating thickness. As this erosion was dependent on the number of silylated groups, RAFT polymerization was used to obtain well-defined structures with controlled MW and low polydispersity (30 000 g·mol −1 ; PDI < 1.3) [226].…”