Synthesis and properties of helical poly(macromonomer) consisting of polyacetylene main chain and poly(methyl methacrylate) side chains

Abstract

The Rh-catalyzed polymerization of an acetylene-terminated poly(methyl methacrylate) (PMMA) macromonomer (M-PMMA) provided a helical poly(macromonomer), poly(M-PMMA) [Mw up to 136,000, weight-average degree of polymerization (DPw) = 80], consisting of a polyacetylene main chain and PMMA side chains. The macromonomer M-PMMA was synthesized by ATRP of MMA initiated by a functionalized initiator, 2-bromo-2-methylpropionic acid (S)-1-methylpropargyl ester (1), in the presence of CuBr/N,N,N′,N″, N″-pentamethyldiethylenetriamine (PMDETA) catalyst/ligand system in toluene at 70°C. Poly(M-PMMA) was a light yellow solid soluble in common organic solvents such as THF, CHCl3, and toluene. Poly(M-PMMA) exhibited a strong CD signal at around 350-357 nm with molar ellipticities ([θ]) of +26300-+27500 deg cm2 dmol-1 in THF, CHCl3, toluene and DMF. This indicates that it possessed a predominantly one-handed helical conformation. Poly(M-PMMA) had stable helical conformation irrespective of solvents and temperature. © 2007 The Society of Polymer Science.