Tadpole Conformation of Gradient Polymer Brushes

• Published in: Macromolecules Vol. 37; no. 11; pp. 4235 - 4240
• Main Authors: Lord, Samuel J, Sheiko, Sergei S, LaRue, Isaac, Lee, Hyung-Il, Matyjaszewski, Krzysztof
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-06-2004
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Structure, morphology and analysis; Terpolymer; Monolayer; Adsorbed layers; Graft copolymer; Functionnally graded material; Ethyl acrylate copolymer; Air water interface; Experimental study; Methyl methacrylate copolymer; Butyl acrylate copolymer; Conformational transition
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma035989z

Cylindrical molecular brushes, each with a gradient of grafting density along the backbone, demonstrated a transition from rodlike to tadpole conformations. Using atomic force microscopy (AFM), a coexistence of two conformational phases was observed within individual molecules adsorbed on a mica substrate. These observations were made by compressing monolayers on the surface of water and then transferring a sample of this monolayer to a mica substrate for AFM studies. Upon compression, the rod−globule transition occurs at the end where the brush is densely grafted, leaving a molecule with a globular “head” and an extended “tail”a so-called tadpole conformation. This research demonstrates the asymmetric changes in the molecular conformation, which is one of the prerequisites for directed motion.