Atom Transfer Radical Polymerization Of N-butyl Acrylate Research Articles

P-Substituted Tris(2-pyridylmethyl)amines as Ligands for Highly Active ATRP Catalysts: Facile Synthesis and Characterization.

A facile and efficient two-step synthesis of p-substituted tris(2-pyridylmethyl)amine (TPMA) ligands to form Cu complexes with the highest activity to date in atom transfer radical polymerization (ATRP) is presented. In the divergent synthesis, p-Cl substituents in tris(4-chloro-2-pyridylmethyl)amine (TPMA3Cl ) were replaced in one step and high yield by electron-donating cyclic amines (pyrrolidine (TPMAPYR ), piperidine (TPMAPIP ), and morpholine (TPMAMOR )) by nucleophilic aromatic substitution. The [CuII (TPMANR2 )Br]+ complexes exhibited larger energy gaps between frontier molecular orbitals and >0.2 V more negative reduction potentials than [CuII (TPMA)Br]+ , indicating >3 orders of magnitude higher ATRP activity. [CuI (TPMAPYR )]+ exhibited the highest reported activity for Br-capped acrylate chain ends in DMF, and moderate activity toward C-F bonds at room temperature. ATRP of n-butyl acrylate using only 10-25 part per million loadings of [CuII (TPMANR2 )Br]+ exhibited excellent control.

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

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.

Synthesis of poly(ϵ-caprolactone)-block-poly(n-butyl acrylate) by the combination of ring-opening polymerization and atom transfer radical polymerization with Ti[OCH2CCl3]4 as a difunctional initiator. II. Synthesis and characterization of poly(ϵ-caprolac

The kinetics and controllability of the Ti[OCH2CCl3]4-initiated atom transfer radical polymerization (ATRP) of n-butyl acrylate were investigated. Then, with Ti[OCH2CCl3]4 as the initiator, poly(ϵ-caprolactone)-block-poly(n-butyl acrylate) (PCL-b-PBA) copolymers were synthesized by the combination of the ring-opening polymerization (ROP) of ϵ-caprolactone and ATRP of n-butyl acrylate. With different sequential combinations of ROP and ATRP, three routes were used to synthesize PCL-b-PBA copolymers. The composition characterization results demonstrated that the first-ROP-then-ATRP route was most efficient; it was followed by the in situ ATRP and ROP route and then the first-ATRP-then-ROP route. Furthermore, with a Haake Rheomix reactor (Thermo Electron Corp., Karlsruhe, Germany), the PCL-b-PBA copolymers were in situ synthesized in a poly(methyl methacrylate) matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Inhibitive Chain Transfer to Ligand in the ATRP ofn-Butyl Acrylate

The N,N,N‘,N‘,N‘ ‘-pentamethyldiethylenetriamine (PMDETA) ligand, commonly used in copper-catalyzed atom transfer radical polymerization (ATRP), is known to have an inhibitive effect on the kinetics of the ATRP of alkyl acrylate monomers due to the chain transfer reaction involving the ligand species. However, the exact chemical nature of the ligand radicals resulting from the chain transfer reaction and other reactions that the ligand radicals may undergo subsequently are presently unknown, making it difficult to establish the precise reaction mechanism of the copper/PMDETA-based ATRP of alkyl acrylate monomers. In an effort to gain a better understanding of the chemistries and reactions of the PMDETA species in the ATRP of n-butyl acrylate, we conducted (i) experimental measurements to determine how changes in PMDETA concentration influence the ATRP kinetics and the molecular properties of the product, (ii) electron density functional theory (DFT) calculations to identify probable pathways for reactions...

Synthesis of Block and Graft Copolymers with Linear Polyethylene Segments by Combination of Degenerative Transfer Coordination Polymerization and Atom Transfer Radical Polymerization

Block and graft copolymers with polyacrylate and linear polyethylene segments were synthesized through a combination of degenerative transfer (DT) ethylene polymerization and atom transfer radical polymerization (ATRP). DT coordination polymerization was mediated by a bis(imino)pyridineiron/diethylzinc binary catalyst system activated by MAO and was studied at various temperatures. The catalyst system achieved a well-controlled DT coordination polymerization of ethylene, resulting in low-polydispersity polyethylene with high chain end functionality. The Zn-terminated polyethylene prepared by DT coordination polymerization was oxidized using dry air, followed by hydrolysis to provide a monohydroxy-terminated polyethylene (PE-OH). The degree of ethylene polymerization (DP ∼ 20) and the chain end functionality (∼80%) of PE-OH were determined by 1H NMR. The PE-OH was converted into a polyethylene α-bromoisobutyrate macroinitiator (PE-MI), and ATRP of n-butyl acrylate and tert-butyl acrylate was successfully c...