Hyperbranched Macromolecules: Soft Particles with Adjustable Shape and Persistent Motion Capability

Abstract

The conformational constraints resulting from dense and regular branching lead to three-dimensional macromolecules which do not interpenetrate and overlap like polymer coils, retaining flexibility of the chain segments and molecular shape. Examples of branched macromolecules with a defined primary structure are dendrimers and comb polymers (molecular brushes). Such highly branched macromolecules can be regarded as soft particles. Their shape is variable and sensitive to intramolecular interactions and perturbations in the surrounding medium. At an interface, the molecular conformation is governed by interplay between intra-molecular interactions of the branches and interaction of the branches with the surface. Within this context, the organization of dendrimers, arborescent graft polymers, and comb polymers on surfaces is discussed with emphasis placed on conformational transitions and motion. Scanning force microscopy is used as a powerful tool for investigation of single molecules and the examination of structural parameters and driving forces that control the shape and the position of molecules on the substrate