Expanding the Scope of the Photoinduced Living Radical Polymerization of Acrylates in the Presence of CuBr₂ and Me₆-Tren

Abstract

Photoinduced living radical polymerization of acrylates is achieved upon UV irradiation (λ max ≈ 360 nm) in the presence of an aliphatic tertiary amine ligand (Me 6 -Tren) in the presence of low concentrations of CuBr 2 , yielding poly(acrylates) with near perfect retention of end group fidelity. The effect of the nature of the solvent on the rate of polymerization was investigated in order to expand the scope and identify the limitations of the system. Subsequently, a range of acrylic monomers containing hydrophobic and hydrophilic substituents have been screened, including lauryl acrylate, octadecyl acrylate and diethylene glycol ethyl ether acrylate, all of which present low dispersities (Đ ≈ 1.1) at very high conversions. Functional monomers, including glycidyl acrylate and solketal acrylate, were also found to be tolerant to the photomediated reaction. Finally, solketal acrylate was copolymerized with methyl acrylate which, following deprotection of the pendant ketal group, furnished an amphiphilic diblock copolymer. Self-assembly of this block copolymer into polymer micelles in aqueous media was exemplified by dynamic light scattering (DLS) and transmission electron microscopy (TEM).

Catalyst-Free Visible Light-Induced RAFT Photopolymerization

“…The initial photopolymerization tests of MA with the four thiocarbonylthio compounds were conducted for 6 and 18 h. The control experiment in the absence of thiocarbonylthio compounds gave no conversions even after 18 h (Table 1, # 6), which is consistent with previous reports (39)(40)(41)45). The photopolymerizations of MA with CPADB (Table 1, (Table 1, # 8) and DDMAT (Table 1, # 9) after 6 h, respectively.…”

Expanding the Scope of RAFT Polymerization: Recent Advances and New Horizons

“…69 However, extension of these metal-catalyzed techniques to other monomer classes has proven difficult. 69,108 One of the challenges in preparing higher order block copolymers by RAFT is that chain ends are inevitably lost during the synthesis of each block as a result of unavoidable termination reactions. Because the activation−deactivation process in degenerative transfer systems does not lead to a change in the overall number of radicals, the number of chains that undergo termination directly corresponds to the number of radicals derived from the decomposition of the initiator.…”

An old kinetic method for a new polymerization mechanism: Toward photochemically mediated ATRP

“…[41][42][43][44][45] However, detailed investigations published by Haddleton and Matyjaszewski showed that a wellcontrolled polymerization should be carried out in a system with excess ligand, and the light-induced ATRP is an ARGET-dominated system with limited contribution from the ICAR mechanism. [46][47][48][49] Overall, with the merit of light in the temporal and spatial control of polymerization, photo ATRP has attracted increasing interest and has been used to synthesize the multiple-block copolymers and surface micropatterns. [50][51][52] However, no detailed kinetic study for this mechanism based on a well-built model has been conducted.…”