Synthesis and properties of amphiphilic “dumbbell”‐shaped grafted block copolymers, 1. Anionic synthesis via a polyfunctional initiator

Abstract

AbstractTwo poly(ethylene oxide) stars linked by a long polystyrene chain represent a novel amphiphilic architecture (dumbbell), which is available by anionic grafting of ethylene oxide from a hydroxylated polybutadiene‐block‐polystyrene‐block‐polybutadiene triblock copolymer. The short butadiene end‐blocks (DPB = 36) of a BSB triblock copolymer with a long styrene middle block (DPS = 650) was first modified by hydroboration and oxidation. A multifunctional alkoxide initiator is thus prepared by titration of the hydroxyl groups of the “polybutadiene” end‐block with cumylpotassium. Gelation and precipitation of the polyfunctional initiator in THF could be avoided by complexing the cation (K+) with a suitable cryptand (Kryptofix[2.2.2]TM). This multifunctional macroinitiator was used to polymerize ethylene oxide. Dumbbell‐shaped molecules with various number and length of PEO branches were synthesized. Some first results about their solution properties are presented and discussed based on viscosity and light scattering measurements.