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

Abstract

Two poly(ethy1ene 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 (DP, = 36) of a BSB triblock copolymer with a long styrene middle block (DP, = 650) was first modificd by hydroboration and oxidation. A multifunctional alkoxide initiator is thus prepared by titration of the hydroxyl groups of the "polybutadiene" endblock with cumylpotassium. Gelation and precipitation of the polyfunctional initiator in THF could be avoided by complexing the cation (K') with a suitable cryptand (Kryptofix[2.2.2ITM). 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.

Triblock copolyampholytes from 5-(N,N-dimethylamino)isoprene, styrene, and methacrylic acid: Synthesis and solution properties

“…Moreover, they are of theoretical relevance for studying principles of macromolecular self-assembly [6][7][8][9][10][11][12][13][14][15][16]. Several studies on the solution behavior of amphiphilic ABC triblock copolymers have been reported.…”

In Honor of Reimund Stadler

“…branched topologies, [44][45][46] with a focus on linear ABC triblock copolymers, [47][48][49][50][51][52][53][54] which actually started with their use as compatibilizers in a polymer blend. [55][56][57] While he declined an offer from the Leibniz-Institut für Polymerforschung Dresden in 1994, he accepted an offer from the Universität Bayreuth and became full professor in Macromolecular Chemistry in 1997, where he stayed for the remainder of his career.…”

Anionic polymerization and copolymerization of macromonomers: Kinetics, structure control

“…[q] limiting viscosity numbers The p parameter corresponds to the ratio of the geometrical defined radius of gyration (R,) and to the hydrodynamic radius (Rh) which is defined through the Stockes-Einstein relation and D (cm' s-') corresponds to the translational diffusion coefficient measured in toluene p = R, / Rh and R h = kT / (6qoD), Anionic copolymerization of macromonomers "Dumbbell" polymers containing a central PS block linking two branched PEO's have been prepared recently (Ref. 15) and were shown to exhibit typical properties of amphiphiles Fig.3. Schematic representation of the structures of branched polymers based on macromonomers They were prepared from triblock copolymers containing terminal hydroxylated segments We have developed another approach to prepare such "dumbbell" species or "palmtree" polymers ( Fig 3) based on anionic homopolymerization of macromonomers The anionic polymenzation of a monofunctional or bifunctional living polystyrene chain was conducted first The carbanionic chain ends served thus as initiator for the anionic polymerization of the a-methacryloyloxy PS macromonomer An example is given on tab 5 In spite of the fact that the molar mass distribution of the precursor chain is rather large, the molar mass of this "palmtree" polymer corresponds to the expected value The calculated value for the DP, of the polymacromonomer @P, =5) is close to the measured value…”