Micelles of poly(isoprene-b-2-vinylpyridine-b-ethylene oxide) terpolymers in aqueous media and their interaction with surfactants

Abstract

Well-defined poly(isoprene-b-2-vinylpyridine-b-ethylene oxide) (PI-P2VP-PEO) triblock terpolymers were synthesized by anionic polymerization high-vacuum techniques. The terpolymers formed spherical three-layer (onion-type) micelles in neutral and acidic pH aqueous media as evidenced by static and dynamic light scattering. In pure water, kinetically frozen micelles with a core composed of a soft PI inner part and a hard P2VP outer shell and protected by a neutral PEO corona were formed. In acidic media the core was formed by the soft PI hydrophobic segment, whereas the corona consisted of an inner cationic polyelectrolyte P2VPH+ part and an outer PEO shell. The aggregation numbers were found to be high in all cases, due to the high hydrophobicity of the core-forming blocks. In the latter case an increase in size was observed due to the electrostatic repulsions between the P2VPH+ chains in the inner part of the corona, which is also responsible for the lower aggregation numbers observed in the acidic solutions. The interaction of these onion-type micelles with cationic (DTMAB) and anionic (SDS) surfactants led to the formation of mixed polymer/surfactant aggregates. Their structural characteristics could be varied by combining changes in surfactant type and concentration, solution pH and type of electrostatic interaction, leading to interesting, block-copolymer-based, environmentally responsive colloidal systems.

Micellization of pH‐sensitive poly(butadiene)‐block‐poly(2 vinylpyridine)‐block‐poly(ethylene oxide) triblock copolymers: Complex formation with anionic surfactants

“…This morphological change leads to an increase of the micellar size as a function of pH and this behavior was also reported by several authors for PS‐P2VP‐PEO and PI‐P2VP‐PEO copolymers . The change of the P2VP hydrophilicity between pH 7 and 3 leads to stronger interchain repulsions and thus to a possible decrease of the aggregation number, as shown by Koutalas et al . for PI‐P2VP‐PEO triblock copolymers.…”

“…An important progress for the preparation of well‐defined ABC type micelles was achieved by Koutalas et al . who investigated the micellization of polyisoprene‐ b ‐poly(2‐vinylpyridine)‐ b ‐poly(ethylene oxide) (PI–P2VP–PEO) copolymers, with the advantage of a very low T g value of the PI block.…”

“…In extension of these studies, and in particular of that by Koutalas et al ., it was of interest to carry out a systematic study concerning the micellization of a homologous series of tailor‐made polybutadiene‐ b ‐poly(2‐vinylpyridine)‐ b ‐poly(ethylene oxide) (PB–P2VP–PEO) copolymers with similar molecular weights. These amphiphilic copolymers are typical pH‐sensitive with a hydrophobic PB sequence of low T g (–20 °C).…”

End-functionalized polymers: Versatile building blocks for soft materials

“…Some examples are ionic polymerization, conventional radical polymerization, polycondensation and controlled radical polymerization (CRP) [20e25,27]. Among these methods, ionic polymerization is usually characterized by narrow dispersity and suited to produce very regular polymers [26]. CRP becomes a new technique that may generate polymers of controlled molecular weight and it may be carried out in the presence of many functional groups from monomers, initiators, or chain transfer agents [22,25,28e33].…”

Micro-phase separation of diblock copolymer in a nanosphere: Dissipative particle dynamics approach

“…In this work, we will present many interesting meso-structures in a nanosphere studied by DPD simulations. Although systems with three-dimension confinement hardly exist in nature, the micelles formed by polymer surfactant are convenient in laboratory and in practical application [37][38][39][40]. The solvent molecules around micelles of polymer surfactant could be looked as a threedimension confinement.…”