Miniemulsion ARGET ATRP via Interfacial and Ion-Pair Catalysis: From ppm to ppb of Residual Copper

Abstract

It was recently reported that copper catalysts used in atom transfer radical polymerization (ATRP) can combine with anionic surfactants used in emulsion polymerization to form ion pairs. The ion pairs predominately reside at the surface of the monomer droplets, but they can also migrate inside the droplets and induce a controlled polymerization. This concept was applied to activator regenerated by electron transfer (ARGET) ATRP, with ascorbic acid as reducing agent. ATRP of n-butyl acrylate (BA) and n-butyl methacrylate (BMA) was carried out in miniemulsion using CuII/tris(2-pyridylmethyl)amine (TPMA) as catalyst, with several anionic surfactants forming the reactive ion-pair complexes. The amount and structure of surfactant controlled both the polymerization rate and the final particle size. Well-controlled polymers were prepared with catalyst loadings as low as 50 ppm, leaving only 300 ppb of Cu in the precipitated polymer. Efficient chain extension of a poly(BMA)-Br macroinitiator confirmed high retention of chain-end functionality. This procedure was exploited to prepare polymers with complex architectures such as block copolymers, star polymers, and molecular brushes.

Ab Initio Emulsion Atom‐Transfer Radical Polymerization

“…Theobtained latex was less stable,s howing complete sedimentation approximately 10 min after the stirring was stopped (see Figure S7). [15] Essentially,a fter crashing the (mini)emulsion, the hydrophilic Br-Cu II TPMA + catalyst migrated into the aqueous phase,l eaving a" pure" product. This peculiar sedimentation phenomenon, observed only for BA with the PEO 1K BiB initiator,w as exploited to purify the polymer:A fter sedimentation, the supernatant was collected, and the polymer particles were washed with water four times.F ollowing this procedure, (96.6 AE 0.6) %o ft he Cu loading remained in the aqueous fractions,a sm easured by inductively coupled plasma mass spectrometry analysis of the obtained polymer.S imilarly, part-per-billion amounts of residual Cu were detected in polymers prepared by miniemulsion ATRP conducted with Cu/TPMA and SDS.…”

“…[15] These two species strongly interacted, resulting in alarge fraction of Cu/TPMA (ca. [15] These two species strongly interacted, resulting in alarge fraction of Cu/TPMA (ca.…”

“…[15] These two species strongly interacted, resulting in alarge fraction of Cu/TPMA (ca. At hird small fraction of Cu/TPMA remained in the aqueous phase.T his catalytic system effectively controlled aminiemulsion ATRP process,d emonstrating good mobility/transfer between phases, [15] and thus emerged as ap romising candidate for ab initio emulsion ATRP. 1%)entered the droplets as neutral ion pairs [Cu I TPMA + /dodecyl sulfate (DS) À ]o r[ Br-Cu II TPMA + /DS À ] ( Figure 1).…”

Temporally Controlled Ultrasonication‐Mediated Atom Transfer Radical Polymerization in Miniemulsion

“…Due to the obvious advantages including excellent control over molecular weight (MW), narrow dispersity (MWD, M w /M n , Ð), [1][2][3][4][5] and ability to incorporate functionality in specific macromolecule place, [6][7][8][9] the most representative RDRP technique is atom and hydrophobic catalyst (dual-catalyst mechanism) in the context of using electric current as a reducing stimulus; [29] moving to single-catalyst approach with only strongly hydrophilic catalyst resulted in excellent control during poly(n-butyl acrylate) polymerization. [23] It was also applied with the use of ascorbic acid as a reducing agent in ARGET ATRP receiving precisely controlled PBA and PBMA macromolecules with different architecture [23] and in photoinduced ATRP under UV light providing temporal control over the polymerization. [5] In this consideration, we investigate sono-ATRP approach in miniemulsion system to synthesize the both homopolymers and copolymers with the use of one strongly hydrophilic catalyst complex (Br-Cu II TPMA + ).…”

Honeycomb-patterned porous films fabricated via self-organization of Tb complex-loaded amphiphilic copolymers

“…[27][28][29][30] Up to now, a variety of polymers, including star polymers, amphiphilic block copolymers, hyper-branched polymers, comb-like copolymers, and rod-coil/coil-coil block copolymers, have been employed to fabricate such porous lms with different pore diameters. [31][32][33][34] Various synthetic routes have been developed to synthesize the star and block polymers, particularly the living radical polymerization including reverse iodine transfer polymerization (RITP), 35 atom transfer radical polymerization (ATRP), 36 and reversible addition-fragmentation chain transfer (RAFT) polymerization. 37 The RAFT polymerization is one of the most prominent living/controlled free radical polymerization techniques as it is applicable to a wide range of monomers to produce well-dened polymers with predictable molecular weights, composition, architecture and low polydispersity index (PDI) values.…”