Lithium Naphthalenides in Non-Polar or in Low Polarity Media: Some Insights Regarding their Use as Initiators in Anionic Polymerizations

MARIO D. NINAGO; MARÍA L. SENA MARANI; VERÓNICA A. GONZÁLEZ; ANGEL J. SATTI; CLAUDIA SARMORIA; MARCELO A. VILLAR; ENRIQUE M. VALLÉS; ANDRÉS E. CIOLINO

POLYMER BULLETIN

SPRINGER

Lugar: Berlin; Año: 2017 vol. 74 p. 307 - 323

0170-0839

The synthesis of bidirectional anionic initiators by the reaction between metallic lithium (Li) and naphthalene (Naph), under mild conditions, in non-polar (benzene) or low polarity media (benzene/THF mixtures) is reported. The efficiency of these initiators to provide macromolecules with well-defined structures was demonstrated. Model linear homo-polymers from styrene (S) or hexamethyl(ciclotrisiloxane) (D3) monomers were synthesized by using classical anionic polymerization (high-vacuum techniques). The model polymers obtained were analyzed using conventional analytical techniques, and showed narrow molar mass distributions, a broad range of molar masses (from 3,000 to 1,000,000 g/mol) and polydispersity indexes (Mw/Mn) lower than 1.1. High molar mass polymers were obtained by using pure benzene as solvent, whereas lower molar masses were obtained in benzene/THF mixtures in which the concentration of THF was lower than 10% v/v. The ratio [Li]/[Naph] and the nature of the reaction medium are the experimental parameters to be controlled in order to obtain the desired lithium naphthalenides.