Synthesis of a model cyclic triblock terpolymer of styrene, isoprene, and methyl methacrylate

Abstract

The synthesis of a model cyclic triblock terpolymer [cyclic(S‐b‐I‐b‐MMA] of styrene (S), isoprene (I), and methyl methacrylate (MMA) was achieved by the end‐to‐end intramolecular amidation reaction of the corresponding linear α,ω‐amino acid precursor [S‐b‐I‐b‐MMA] under high‐dilution conditions. The linear precursor was synthesized by the sequential anionic polymerization of S, I, and MMA with 2,2,5,5‐tetramethyl‐1‐(3‐lithiopropyl)‐1‐aza‐2,5‐disilacyclopentane as an initiator and amine generator and 4‐bromo‐1,1,1‐trimethoxybutane as a terminator and carboxylic acid generator. The separation of the unreacted linear polymer from the cyclic terpolymer was facilitated by the transformation of the unreacted species into high molecular weight polymers by the evaporation of the reaction solvent and the continuation of the reaction under high‐concentration conditions. The intermediate materials and the final cyclic terpolymer, characterized by size exclusion chromatography, vapor pressure osmometry, thin‐layer chromatography, IR and NMR spectroscopy, exhibited high molecular weight and compositional homogeneity. Dilute‐solution viscosity measurements were used as an additional proof of the cyclic structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1476–1483, 2002

The influence of polymer topology on pharmacokinetics: Differences between cyclic and linear PEGylated poly(acrylic acid) comb polymers

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Synthesis of polyisoprene–poly(methyl methacrylate) block copolymers via a two‐electron‐transfer mechanism

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Metathesis Polymer Cyclization with Telechelic Poly(THF) Having Allyl Groups

“…[15][16][17][18][19] In this process, the two end groups of the polymer precursor become complementarily reactive with each other after the deprotection or the activation, and the reaction under dilution gives a cyclic polymer product. The cyclization efficiency was notably improved since the inherent stoichiometric balance is maintained between complementarily reactive groups located within the same polymer molecule, and the reaction follows the unimolecular kinetics depending solely on the concentration of the polymer precursor.…”