Block Copolymer Thermodynamics: Theory and Experiment

TLDR

Block copolymers are macromolecules composed of distinct repeat‑unit blocks, first enabled by termination‑free anionic polymerization, and include AB, ABA, and star‑block architectures derived from two or more monomer types. The authors synthesize block copolymers via stepwise anionic polymerization: a two‑step route yields (A‑B) dioblocks, a three‑step route gives (ABA) or (BAB) triblocks, and coupling of living diblocks with an n‑functional agent produces (A‑B)n star‑block copolymers.

Abstract

Block copolymers are macromolecules composed of sequences, or blocks, of chemically distinct repeat units. The development of this field originated with the discovery of termination-free anionic polymerization, which made possible the sequential addition of monomers to various carbanion-ter­ minated (living) linear polymer chains. Polymerization of just two dis­ tinct monomer types (e.g. styrene and isoprene) leads to a class of materials referred to as AB block copolymers. Within this class, a variety of molec­ ular architectures is possible. For example, the simplest combination, obtained by the two-step anionic polymerization of A and B monomers, is an (A-B) dioblock copolymer. A three-step reaction provides for the preparation of (ABA) or (BAB) triblock copolymer. Alternatively, living diblock copolymers can be reacted with an n-functional coupling agent to produce (A-B)n star-block copolymers, where n = 2 constitutes a triblock copolymer. Several representative (A-B)n block copolymer architectures