Macromolecules, Vol.37, No.4, 1234-1242, 2004
Anionic synthesis and characterization of omega-hydroxyl-functionalized poly(1,3-cyclohexadiene)
The amount of chain transfer to monomer during the alkyllithium-initiated polymerization of 1,3-cyclohexadiene has been evaluated by characterization of the products from ethylene oxide termination. The products were separated by column chromatography and characterized by SEC, TLC, H-1 NMR, and MALDI-TOF MS. The highest yields (90%) of omega-hydroxyl-functionalized poly(1,3-cyclohexadiene) [M-n(calcd) = 3000] were obtained in benzene or in the presence of N,N,N'N'-tetramethylethylenediamine (TMEDA) or lithium 2,3-dimethyl-3-pentoxide (LDP); in the presence of 1,4-diazobicyclo[2.2.2] octane (DABCO), the yield was 81%. All unfunctionalized polymer fractions exhibited lower M. values and broader molecular weight distributions compared to functionalized polymers; the exact masses determined by MALDI-TOF MS were consistent with termination by chain transfer to monomer and not decomposition by loss of lithium hydride. The occurrence of reinitiation after chain transfer was investigated by MALDI-TOF MS; reinitiation occurs in the presence of DABCO but not in the presence of either TMEDA or LDP.