Synthesis and Properties of Helical Poly (macromonomer) Consisting of Polyacetylene Main Chain and Poly (methyl methacrylate) Side Chains

The Rh-catalyzed polymerization of an acetylene-terminated poly(methyl methacrylate) (PMMA) macromonomer (M-PMMA) provided a helical poly(macromonomer), poly(M-PMMA) [M w up to 136,000, weight-average degree of polymerization (DP w ) = 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 (I), in the presence of CuBr/N,N,N',N",N"-pentamethyldiethylene-triamine (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, CHCl 3 , and toluene. Poly(M-PMMA) exhibited a strong CD signal at around 350-357 nm with molar ellipticities ([θ]) of +26300-+27500 deg cm 2 dmol -1 in THF, CHCl 3 , 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.