Catalytic Halogen Exchange in Supplementary Activator and Reducing Agent Atom Transfer Radical Polymerization for the Synthesis of Block Copolymers

Abstract

Synthesis of block copolymers (BCPs) by catalytic halogen exchange (cHE) is reported, using supplemental activator and reducing agent Atom Transfer Radical Polymerization (SARA ATRP). The cHE mechanism is based on the use of a small amount of a copper catalyst in the presence of a suitable excess of halide ions, for the synthesis of block copolymers from macroinitiators with monomers of mismatching reactivity. cHE overcomes the problem of inefficient initiation in block copolymerizations in which the second monomer provides dormant species that are more reactive than the initiator. Model macroinitiators with low dispersity are prepared and extended to afford well‐defined block copolymers of various compositions. Combined cHE/SARA ATRP is therefore a simple and potent polymerization tool for the copolymerization of a wide range of monomers allowing the production of tailored block copolymers.

Controlled Polymer Synthesis Toward Green Chemistry: Deep Insights into Atom Transfer Radical Polymerization in Biobased Substitutes for Polar Aprotic Solvents

“…Initially, the polymerization of n BA and t BA in N , N -dimethylformamide (DMF) was conducted to assess the comparative efficiency of using conventional harmful organic solvents versus their naturally derived, nontoxic counterparts, Cyrene and Cygnet 0.0, as the reaction medium for SARA ATRP. In these model polymerizations, we employed ethyl α-bromoisobutyrate (EBiB) as the ATRP initiator, copper wire as both a reducing agent and supplementary activator, and a catalytic complex consisting of copper­(II) bromide, along with tris­(2-pyridylmethyl)­amine (TPMA) as the ligand, which is commonly used in polymerization of acrylates , (Table S1). Polymerizations were carried out at [monomer] 0 /[EBiB] 0 /[Cu II Br 2 /TPMA] 0 = 80–120/1/0.036 initial molar ratios.…”

Dual electrochemical and chemical control in atom transfer radical polymerization with copper electrodes

“…39,44,45 We attempted SARA ATRP of MMA in ethanol initiated by BPN at 50 C and catalyzed by [Cu II TPMA] 2+ (TPMA ¼ tris(2-pyridilmethyl)amine), utilizing catalytic halogen exchange (cHE, with 0.05 M Bu 4 NCl) to suppress the mismatch of reactivity. 39,[46][47][48][49][50] This SARA ATRP (Table 5, entry 3) was unsuccessful, even with cHE, and resulted in a poorly controlled PMMA-Cl, with a multimodal MW distribution (M n ¼ 31.6 kDa, Đ ¼ 1.86). However, using the same conditions but superimposing electrochemical control with a potentiostatic electrolysis at E app ¼ E 1/ 2 + 0.06 V (E 1/2 ¼ À0.714 V vs. ferrocenium/ferrocene), the polymerization greatly improved (Table 5, entry 4).…”

Electrochemistry for Atom Transfer Radical Polymerization

“…This exchange allows efficient activation of the initial macroinititator and a regular growth of the second block, according to a controlled ATRP. c HE has been applied also to the production of block copolymers by SARA ATRP for the synthesis of PBA 88 ‐ b ‐PAN 594 , PAN 100 ‐ b ‐PMMA 307 , POEOA 26 ‐ b ‐(POEOA 16 ‐ stat ‐POEOMA 102 ), and PS 87 ‐ b ‐PMA 79 (PS=polystyrene) [47c] …”