Synthesis of Dendronized Polymers via MacromonomerApproach by Living ROMP and Their Characterization: From Rod-LikeHomopolymers to Block and Gradient Copolymers.

Dendronized polymers were synthesizedfrom various endo-tricycle[4.2.2.0]deca-3,9-diene(TD) monomers, using a macromonomerapproach, via ring-opening metathesis polymerization. The polymerizationwas achieved in a living manner to give dendronized polymers withhigh molecular-weights and narrow polydispersity index. The resultingpolymers showed highly extended conformations both in solution andin the solid state, even with relatively small third-generation esterdendrons, because of the rigid backbone of TD monomers. Using theirrigidity, block and gradient copolymers containing TD and norbornenemoieties were synthesized. Diblock copolymers were produced by thesequential addition of two dendronized macromonomers, and gradientcopolymers were produced in a simple batch reaction, because largedifferences in reactivity allowed for the simultaneous one-pot polymerization,favoring TD over norbornene. Polymer conformations were confirmedby both scattering analysis in solution and atomic force microscopy(AFM) imaging in thin films. The high-resolution AFM images of bothcopolymers enabled us to distinguish the structural differences betweenthe two classes of copolymers because the block copolymer showed clearboundary for each block while the gradient copolymer showed gradualchanges in height and thickness. Furthermore, a comparison of therigidities of these two copolymers was performed by scattering analysisin solution. [ABSTRACT FROM AUTHOR]