Synthesis and post-polymerization reaction of end-clickable stereoregular polymethacrylates via termination of stereospecific living anionic polymerization

Abstract

ARTICLE This journal is © The Royal Society of Chemistry 2013J. Name., 2013, 00, 1-3 | 1 Poly(methyl methacrylate)s with high stereoregularity and clickable end-groups were synthesized via terminating reactions with α-(halomethyl)acrylates in stereospecific living anionic polymerization. The terminating reaction was so efficient and tolerant to the reaction conditions that almost quantitative end-functionalization was achieved in isotactic-and syndiotactic-specific polymerization systems. The terminating reactions were also achieved in the polymerizations of vinyl methacrylate and trimethylsilyl methacrylate. For the polymerization of butyl acrylate, however, the termination efficiency was limited as high as 69%. Further quantitative end-functionalization of the incorporated C=C double bond at ω-end was achieved with various thiols catalyzed by Et3N. The base-catalysed thiol-ene reaction of the stereoregular poly(vinyl methacrylate) with ω-end C=C double bond proceeded selectively to retain vinyl ester functions, and the subsequent hydrolysis afforded ω-functional stereoregular poly(methacrylic acid). A combination of the terminating agent with a protected lithium amide afforded stereoregular poly(methyl methacrylates) with orthogonally clickable α-and ω-ends.

Termination of Living Anionic Polymerization of Butyl Acrylate with α‐(Chloromethyl)acrylate for End‐Functionalization and Application to the Evaluation of Monomer Reactivity

“…Li‐ i PrIB was prepared and recrystallized in toluene according to our previous report . ECMA was synthesized according to our previous reports . Other reagents were used as purchased without further purification.…”

“…Besides the signals of the monomeric units (signals labeled 1–6 ), signal α (4.94 ppm) assignable to the isopropyl methine proton at the α‐end group is clearly observed, which can be used as an internal standard for quantitative analyses of polymer structures. Olefinic proton signals ω1 (5.51 ppm) and ω2 (6.15 ppm) are assignable to the ω‐end unit formed by the termination reaction of the living poly( n BA) anions with ECMA through addition–elimination (S N 2′) mechanism (Scheme ), similarly to the case of MMA polymerization . The ethoxyl methylene signal ω3 (4.19 ppm) is also observed, further confirming the assignments.…”

“…We have been interested in the polymerization behavior of α‐substituted acrylates and recently have found that α‐(halomethyl)acrylate and α‐(alkoxymethyl)acrylate functioned as an efficient terminator in stereospecific anionic polymerizations of methyl methacrylate (MMA); the poly(methyl methacrylate) (PMMA) living anion attacks the vinylidene group of the terminators, and the subsequent elimination of halogen atom or alkoxy group generates PMMA with α,β‐unsaturated ester moiety at the ω‐end. For example, the polymerization initiated by isopropyl α‐lithioisobutyrate (Li‐­ i PrIB) in the presence of ethylaluminum bis(2,6‐di‐ tert ‐butylphenoxide) [EtAl(ODBP) 2 ] could be terminated with ethyl α‐(chloromethyl)acrylate (ECMA) to afford highly syndiotactic ( st ‐) PMMA with ω‐functionality (termination efficiency: F ≈ 99%) . Furthermore, the incorporated α,β‐unsaturated ester moiety allows quantitative postpolymerization modification to incorporate ω‐functional groups such as amino, hydroxyl, and carboxylic group via base‐catalyzed thiol‐ene reactions, one of the widely practiced click reactions …”

“…For example, the polymerization initiated by isopropyl α‐lithioisobutyrate (Li‐­ i PrIB) in the presence of ethylaluminum bis(2,6‐di‐ tert ‐butylphenoxide) [EtAl(ODBP) 2 ] could be terminated with ethyl α‐(chloromethyl)acrylate (ECMA) to afford highly syndiotactic ( st ‐) PMMA with ω‐functionality (termination efficiency: F ≈ 99%) . Furthermore, the incorporated α,β‐unsaturated ester moiety allows quantitative postpolymerization modification to incorporate ω‐functional groups such as amino, hydroxyl, and carboxylic group via base‐catalyzed thiol‐ene reactions, one of the widely practiced click reactions …”

α-(Aminomethyl)acrylate: polymerization and spontaneous post-polymerization modification of β-amino acid ester for a pH/temperature-responsive material

“…Recently, we have reported the unique polymerization chemistry of various α-functionalized acrylates. [18][19][20][21][22][23] Along the 35 line of this concept, methyl and ethyl α-(aminomethyl)acrylates, 2a and 2b, were designed which are structural isomers of 2-aminoethyl acrylate and 1, respectively, the sources for watersoluble polymers (Scheme 1). α-(Aminomethyl)acrylate and its analogues are found in nature 40 as metabolic products by some sponges 24,25 and the total syntheses have reported by Holm et al 26 In this report, the synthetic method was slightly modified for gram-scale preparation desirable for polymerization experiment; 2a was prepared through the reaction of methyl α-(chloromethyl)acrylate 45 with aqueous ammonia.…”