Formation of interpolyelectrolyte complexes (IPEC) between sodium poly(4-styrenesulfonate) (PSSO3Na) and a diblock copolymer consisting of a protonated poly(2-vinylpyridine) (P2VP) block and a neutral poly(ethylene oxide) (PEO) one was investigated in water. The main experimental variables were the molecular weight (MW) of the PSSO3Na polyanion, the molar ratio of the cationic and anionic species (i.e., the stoichiometry of the complex), and the pH of the aqueous solution. It was observed that (i) the interpolyelectrolyte complexes self-assemble at least at low pH into the core of monodisperse spherical micelles surrounded by a corona of PEO blocks and possibly of uncomplexed PSSO3Na segments, (ii) their stability depends on the pH in relation to the degree of protonation of the P2VP block, whatever the MW of the PSSO3Na polyanion and the cation/anion stoichiometry, (iii) the complexes are dissociated above a critical pH and are salt-sensitive, falling apart above a critical salt concentration, and (iv) a cooperative mechanism operates, which is completely reversible.

A series of poly(2-vinylpyridine)-block-poly((dimethylamino)ethyl methacrylate) diblock copolymers (P2VP-b-PDMAEMA) have been synthesized by living anionic polymerization of the comonomers. Dynamic light scattering (DLS) has been used to study the associative behavior of these copolymers in water as a function of copolymer composition, pH, ionic strength, and temperature. Three association regimes are observed. At low pH, loose aggregates are formed, although both the P2VP and PDMAEMA blocks are protonated. At intermediate pH, micelles are observed that consist of an uncharged hydrophobic P2VP core surrounded by a protonated PDMAEMA corona. At higher pH, the PDMAEMA corona is essentially uncharged and collapses at temperatures higher than 40 °C, which results in unstable micelles. The micelles observed by transmission electron microscopy are spherical.

Amphiphilic block copolymers, composed of poly(sodium methacrylate) (PMANa) as the water soluble sequence and poly((dimethylamino)ethyl methacrylate) (PDMAEMA) as the hydrophobic sequence, were anionically synthesized. Due to their amphiphilic character, these polymers aggregate into micelles in aqueous solutions. Of particular interest is the possibility of exchange of free chains, called unimers, between micelles and the bulk and the quantification of the exchange rate. The exchange of unimers between the micellar aggregates was determined spectroscopically. A donor molecule, naphthalene, was covalently bound to the hydrophobic blocks of the copolymers, while the acceptor, pyrene, was dissolved in aggregates built up from an identical, but unlabeled, copolymer. The energy transfer from an excited donor to a ground-state acceptor, with subsequent emission from the acceptor, was used to follow the migration of donor-labeled chains into micelles containing the dissolved acceptor. These data were analyzed according to a kinetic model, and the respective kinetic parameters could be determined. The influence of the relative composition of the block copolymer on the exchange rate was investigated to illustrate the usability of the kinetic model. While keeping the relative amount of comonomers as well as the molecular weights constant, the molecular architecture was also studied:  hence the diblock (PDMAEMA-b-PMANa) and the corresponding triblocks (PDMAEMA-b-PMANa-b-PDMAEMA) and (PMANa-b-PDMAEMA-b-PMANa) were investigated.

The anionic polymerization of a series of methacrylates, i.e. methyl methacrylate (MMA), tert-butyl methacrylate (tBuMA), (dimethylamino)ethyl methacrylate (DMAEMA), and glycidyl methacrylate (GMA), has been investigated in THF at −78 °C, by using both lithium diisopropylamide (LDA) and α-lithioethyl isobutyrate (Li-EIB) complexed with LiCl as initiators. Compared to ligated Li-EIB, which is a model for the propagating enolate in the methacrylate anionic polymerization, ligated LDA has quite a comparable initiation efficiency (>90%) and gives rise to polymers with a predictable molecular weight and a narrow molecular weight distribution (MWD < 1.1). The effect of LiCl on the MWD of poly-GMA is less pronounced compared to the other polymethacrylates. An already narrow MWD in the absence of LiCl might be accounted for by an intramolecular coordination of the ion pair by the oxirane group of the (ante)penultimate unit(s) of growing poly GMA. As a direct consequence of the well-controlled anionic polymerization of these methacrylates, pairs of them have been polymerized in a sequential way with formation of well-defined block copolymers. Actually, there is no restriction on the addition order of the comonomers, so that both types of triblocks (ABA and BAB) can be successfully synthesized. Size exclusion chromatography supports that block copolymers are not contaminated by homopolymers, at least in detectable amounts.