Preparation and Fractionation of Poly(ethylene oxide)‐Poly(N‐tert‐butylacrylamide) Alternating Multiblock Copolymers

Abstract

AbstractPreparation and fractionation of poly(ethylene oxide) (PEO)‐poly(N‐tert‐butylacrylamide) (PNtBAm) alternating multiblock (AMB) copolymers have been reported. A reversible addition‐fragmentation chain transfer (RAFT) polymerization is used for preparing α,ω‐dicarboxy PNtBAm. 1H NMR measurements reveal that the conversion of N‐tert‐butylacrylamide (NtBAm) becomes 78% at 30 min after the initiation, and then reaches plateau with ca. 88% at 60 min. The molecular weight distribution of α,ω‐dicarboxy PNtBAm is 1.1–1.2, indicating that the RAFT polymerization is successfully carried out. α,ω‐Dicarboxy PNtBAms with 10 and 19 of the polymerization degree have been used to prepare PEO‐PNtBAm AMB copolymers after the active esterification. The precipitation fractionation of PEO‐PNtBAm AMB copolymers is performed with an acetone/n‐hexane mixed solvent. The molecular weight of the fractionated samples decreases in the order of precipitation, while the PEO/PNtBAm ratio of the fractionated samples is almost identical. The precipitation fractionation of the PEO‐PNtBAm AMB copolymer can be carried out in the same manner for general homopolymers.