Intermacromolecular complexes due to specific interactions. 13. Formation of micelle-like structure from hydrogen-bonding graft-like complexes in selective solvents

The complexation between poly(4-vinyl pyridine) (PVPy) and mono-carboxy terminated polystyrene (MCPS) in chloroform leads to the formation of a graft-like supramolecular architecture. LLS and fluorescence spectroscopy have been used to monitor the self-assembly process of the "graft" copolymers in a selective mixed solvent of chloroform/toluene which is a solvent for MCPS but a nonsolvent for PVPy. Adding toluene to PVPy/MCPS-1.8 blend solution in chloroform leads to a stable and clear solution indicating the formation of the micellelike core-shell structure with the core and shell made of PVPy and MCPS, respectively. Here, the cores and shells are linked by hydrogen bonding. The final micelle-like particles are narrowly distributed and very stable on standing. Adding the blend solution of PVPy and MCPS in chloroform to an excess of toluene also produces micelles but these have a much smaller average hydrodynamic radius ([R-h]) than those prepared by adding toluene to the blend solution. As the molar mass of MCPS is increased, the size of micelle-like structures increases dramatically. (C) 2000 Elsevier Science Ltd. All rights reserved.