A simplified electrochemically mediated ATRP synthesis of PEO-b-PMMA copolymers

Abstract

Poly(ethylene oxide)-block-poly(methyl methacrylate) amphiphilic copolymers were prepared via electrochemically mediated atom transfer radical polymerization (eATRP) utilizing only 50 ppm of Cu II complex, rather than previously reported concentrations of catalyst of ca. 1,000-30,000 ppm. The copolymers were also prepared via a simplified electrochemically mediated ATRP (seATRP) procedure utilizing an aluminum wire sacrificial anode as a counter electrode, which was directly immersed into the reaction flask, without the need fo its separation. This seATRP system works under both potentiostatic and galvanostatic conditions. In each case the polymerization results showed similar molecular weight evolution while maintaining a narrow molecular weight distribution throughout the reactions. The successful chain extension and formation of block copolymers confirmed the living nature of the poly(alkyl methacrylates) prepared by eATRP and seATRP.

Cellulose-based graft copolymers prepared by simplified electrochemically mediated ATRP

“…The sacrificial CE was Al wire (l = 10 cm, d = 1 mm). Values for potentials applied for electrolysis were established from CV measurements at a 100 mV/s scan rate using saturated calomel electrode (SCE; Gamry) RE according to the previous research [33].…”

“…ATRP is one of the most utilized technique to produce polymers with precise and complex architectures, predetermined molecular weight distribution (M w /M n , MWD), degrees of polymerization (DP), and high end group fidelity [26][27][28][29]. The advent of (re)generation of transition metal with ligands catalysts concepts allows use of ppm level of catalyst for ATRP, such as simplified electrochemically mediated ATRP (seATRP) [30], which uses electric current as external stimulus to reduce deactivator to the activator species [30][31][32][33][34]. seATRP can be conducted at a fixed E app (constant potential electrolysis conditions) in a three-electrode cell, with working electrode (WE), counter electrode (CE), and reference electrode (RE).…”

Synthesis of cationic star polymers by simplified electrochemically mediated ATRP

“…Well-controlled ATRP synthesis of star polymers is challenging when chain extension occurs from a macroinitiator of lower activity to a more active monomer [24]. The rate of activation of a bromo-terminated PDMAEMA chain end is faster than the activation of a 2-bromoisobutyrate β-CD chain ends (ω-functional arms) [55,56].…”

“…The structure of the ligand, monomer, dormant species as well as reaction conditions (solvent, temperature and pressure) can strongly influence the values of the rate constants (k a , k da and K ATRP (= k a /k da )) [5,19]. In most cases electrochemically mediated ATRP reactions were carried out in DMF [14,15,19,23,24] and acetonitrile (MeCN) [20] as solvents. The polymerization in DMF was faster in comparison to the reactions conducted in MeCN, this is because more polar system could enhance ATRP equilibrium constants (K ATRP = k a /k da ) [59].…”

“…Consequently, the radical species propagate to form polymeric chains by reacting with monomers (M), or are deactivated back to the dormant species (P n -X) ( Figure 1) [14,15,17,18]. This method has been applied to hydrophobic (meth) acrylates [14,15,[19][20][21][22][23][24][25][26], and hydrophilic (meth)acrylates and (meth)acrylamides [14, 16-18, 25, 27-31] for the synthesis of well-defined polymeric architec-tures. Star-shaped cationic polymers, consisting of multiple arms linked to a central β-cyclodextrin (β-CD) core, have recently attracted much attention, because of their dense branched architecture with moderate flexibility, tunable properties like solubility, chemically crosslinked structure, temperature or pH sensitivity, which could be manipulated by the parameters such as the block composition, MW, and arm number [32][33][34][35][36][37][38][39][40][41][42][43][44].…”