Homogeneous anionic polymerization. I. Molecular weights of polystyrene initiated by sodium naphthalene

Abstract

A study has been carried out on the molecular weight distributions of polystyrene initiated by sodium naphthalene in tetrahydrofuran solution. Stringent high‐vacuum techniques were used in order to minimize initiator destruction or chain termination. Molecular weights were measured by osmotic pressure, dilute solution viscosity, light scattering and sedimentation equilibrium. In general, the molecular weight distributions found were quite narrow, as predicted, and corresponded to a stoichiometry of one polymer chain for two initiator molecules. However, the breadth of the distribution was very sensitive to experimental conditions, the M̄w/M̄n values found ranging from 1.1 to 1.5. At the higher molecular weights, there was some indication of a chain transfer reaction, leading to a lower molecular weight than expected, as well as a broadening of the distribution. This transfer reaction did not appear to be due to any transfer step between the short‐lived radical‐anions and the solvent.

More on the Analysis of Dilute Solution Data: Polystyrenes Prepared Anionically in Tetrahydrofuran

“…Polystyrene was prepared by anionic polymerization at -78°C (with a Dry Ice-methanol mixture) according to the procedure of Morton, et al, 9 • 10 using tetrahydrofuran as a solvent and n-butyllithium as an initiator. The termination of polymerization was achieved with a methanol -butanol mixture.…”

Facile one‐pot synthesis of linear and radial block copolymers of styrene and isoprene through a novel coupling agent by living anionic polymerization

“…MC (Aldrich, 97%) was dried over calcium hydride, vacuum distilled, diluted with toluene, and sealed in glass ampoules equipped with break seals. Toluene (Aldrich, 99%) was purified using standard high vacuum‐technique described elsewhere 19, 20. The initiator sec ‐butyllithium ( s ‐BuLi) (Aldrich, 1.6 M in hexane), calcium hydride (Junsei, 95%), n ‐butyllithium (Aldrich 1.6 M in hexane), and 1,1‐diphenylethylene (Aldrich, 97%) were used as received without further purification.…”

Synthesis and Characterization of Star Copolymers Consisting of Fullerene and Conjugated Polyphenylene: 6-star-C60[styrene−poly(1,4-phenylene)-block-polystyrene] and 6-star-C60[polystyrene-block-poly(1,4-phenylene)]

“…10 -3 -10 -4 Pa), set with break-seal ampules. [34][35][36] A known quantity of initiator, s BuLi, was added to purified toluene in a break-seal on the vacuum line immediately prior to use. MeOH, st and CHD were distilled into break-seals.…”