Association of block copolymers in selective solvents 2. Viscosity, diffusion and light‐scattering measurements on hydrogenated poly(styrene‐isoprene) in trans‐decalin/decane mixtures

Abstract

The association of a hydrogenated poly(styrene-isoprene) block copolymer has been studied in mixtures of a selective (decane) and a non-selective solvent (trans-decalin). Viscosity, diffusion and light-scattering studies were made within the temperature range of 25-100°C. Relatively small, compact micelles with a rather monodisperse distribution are found at low temperatures and high decane concentrations; very large, polydisperse associates are formed at intermediate decane concentrations and also at increasing temperature from the compact micelles prior to complete dissociation. These large particles have no particular effect on the inherent viscosity, which shows a gradual, continuous decrease as the polymer passes from the associated to the dissociated state. The association also gives rise to drastic changes in the UV absorption of the polystyrene part of the polymer. Kinetic experiments indicate a time scale of the order of ten seconds for the association-dissociation transition.The authors wish to thank Messrs. M. S. de Groot and J. M. Wortel for their interest, and for the valuable comments they made during discussions in the course of this work.

Thermodynamics of Crew-Cut Micelle Formation of Polystyrene-b-Poly(acrylic acid) Diblock Copolymers in DMF/H2O Mixtures

“…Optically clean solutions of small macromolecular particles should have a Z value near unity . Several research groups have investigated the asymmetry factor Z as a function of temperature near the onset of the micellization and found that there is a peak that in some cases appears at the same temperature as the peak in the scattering curve (see Figure ). ,,− We also observed a maximum in the plot of Z as a function of temperature. This is shown in Figure for the 0.77 and 0.97 wt % fractionated block copolymer samples in DMF containing 4.50 wt % water.…”

Self-Assembly of a Novel Organometallic−Inorganic Block Copolymer in Solution and the Solid State: Nonintrusive Observation of Novel Wormlike Poly(ferrocenyldimethylsilane)-b-Poly(dimethylsiloxane) Micelles

“…In addition, spherical micelles have been observed in many studies of block copolymers in solution where the solvent preferentially solvates one of the blocks. Although there are several reports in the literature of the formation of cylindrical micelles − from block copolymers, such systems are uncommon, and understanding of them remains poor. Many of the early reports of nonspherical micelles were complicated by the so-called anomalous effect in which certain block copolymer solutions would exhibit a milky opalescence with a large angular dissymmetry at concentrations or temperatures near the onset of micellization …”

Micellization of ω-Functionalized Poly(styrene-b-isoprene) Copolymers in n-Decane

“…On the other hand it is a well-established fact that block copolymers consisting of nonpolar dissimilar blocks can form micelles in selective solvents, − i.e. solvents that are good for one block but are precipitants for the other.…”