Branch-Controlled ATRP Via Sulfoxide Chemistry

Abstract

A vinyl-containing macroinimer was prepared in situ by utilizing sulfoxide chemistry in an unprecedented manner and allowed for the one-pot synthesis of hyperbranched polymers. Sulfoxide-protected haloalkanes were prepared, and their transformation into vinyl-functionalized haloalkanes through sulfoxide elimination under various reaction conditions was investigated. The protected haloalkanes were employed as an initiator for supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) in a diluted catalytic system to prepare polymers with a high chain-end functionality at a relatively low temperature. Subsequent thermal treatment yielded the macroinimers while preserving the high chain-end functionalities. When the temperature was elevated during the linear polymerization, hyperbranched polymers were afforded in a one-pot process via the in situ generations of the macroinimers. A detailed investigation revealed that the sulfoxide-modified ATRP initiator to protect the vinyl functionality on the polymer chain was successfully utilized for the synthesis of the hyperbranched polymer. This strategy is expected to aid in the synthesis of hyperbranched polymers with a tunable distance between the branch points.

Controlled Dual Cross-Linking of Radical and Urethane Reactions via Vinyl Protection for High-Performance Coating Materials

“…The degree of vinyl deprotection and the rate constant, k , of the sulfoxide elimination reaction were predicted using eqs and . deprotection .25em ( % ) = 100 − ( e − k · time false( normals false) ) × 100 k = A normale − E normala / R T Here, A , E a , R , and T are constants (1.22 × 10 13 ), activation energy (118 kJ mol –1 ), gas constant (8.314 J mol –1 K –1 ), and absolute temperature (K), respectively. The A and E a values were obtained from a previous kinetics study …”

“…The A and E a values were obtained from a previous kinetics study. 26 Preparation of Clearcoat Samples. The formulations of the SVP (or VP) clearcoat samples used for mono-cross-linking (i.e., either radical addition (R-curing) or urethane formation (U-curing)) and dual-cross-linking (D-curing) processes are listed in Table 1.…”

“…For example, acrylate-protection/deprotection-exploiting sulfoxide chemistry was reported by Melwig et al, 25 and vinyl protection, including that using methacrylate, acrylate, and styrene via sulfoxide chemistry, as well as the sulfoxide deprotection kinetics, has been investigated in previous studies. 26 In addition, the real-time radical cross-linking behavior when the vinyl functionalities are controlled via sulfoxide chemistry has been examined. 27 In this paper, we report the enhanced dual-cross-linking reactions (radical addition and urethane formation reactions) that are possible via vinyl protection/deprotection using sulfoxide chemistry (Scheme 1a).…”

Metal-free synthesis of an estetrol key intermediate under intensified continuous flow conditions

“…15,16 The thermolysis of sulfoxides, also known as a thermal desulfinylation reaction, is a thermal syn-elimination which has been widely documented in the literature as a valuable synthetic methodology. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Despite its potential for the production of 1, the thermolysis of sulfoxides requires harsh conditions (high temperatures and long reaction times in batch), which increases the likelihood of product degradation, thermal alkene isomerization, and decreases the selectivity toward the target product. Using selenoxide derivatives instead significantly reduces the activation barrier, yet the toxicity of organoselenium derivatives limits the applicability of such a reaction for pharmaceutical purposes.…”

Synthesis and visualization of bottlebrush-shaped segmented hyperbranched polymers

“…To date, three main techniques have been developed to synthesize SHBPs by one-pot polymerization, including (1) step-growth polymerization of AB n (n ≥ 2) macromonomers, [4][5][6][7][8][9][10][11] (2) copolymerization of A 2 macromonomers with B 3 [12][13][14][15][16] and (3) the simultaneous chain-and step-growth self-condensing vinyl polymerization (SCVP) of inimers ( polymerizable initiators) with monovinyl monomers. [17][18][19][20][21][22] Although the macromonomer strategies can offer precise control over linear segments for SHBPs, the synthesis of telechelic macromonomers is tedious and gelation remains an unavoidable problem in the copolymerization of A 2 macromonomers with B 3 strategy. 23 The SCVP of inimers and functional comonomers is popularly used for synthesizing functional SHBPs via the reversible deactivation radical polymerization (RDRP) technique due to its excellent functional group tolerance and mild polymerization con-ditions, such as in the SCVP based on atom transfer radical polymerization (SCVP-ATRP) [24][25][26][27] or reversible addition-fragmentation chain transfer (RAFT) polymerization (SCVP-RAFT).…”