Stimuli-responsive molecular brushes

Molecular brushes are composed of a flexible backbone and densely grafted side chains. The conformation of molecular brushes is governed by side chains separated by a distance much smaller than their unperturbed dimensions, which leads to significant monomer congestion and entropically unfavorable extension of both the backbone and side chains. Generally, conformation as well as changes in physical properties of polymers can be influenced by external stimuli, such as solvent, temperature, pH, and light. The mechanisms and driving forces for the conformational variation in response to external stimuli are unique for molecular brushes since these conformational changes can be restricted to a single molecule. In this article, we review the general aspects of molecular brushes and polymeric responsive systems. Rational approaches to induce stimuli-responsiveness in molecular brush systems are highlighted. (C) 2009 Elsevier Ltd. All rights reserved.