Inscriere cercetatori

Site nou !

Daca nu va puteti recupera parola (sau aveti alte probleme), scrieti-ne la pagina de contact. Situl vechi se gaseste la adresa old.ad-astra.ro

Facebook

Synthesis of (vinyl acetate)-terminated polystyrene macromonomers by free-radical polymerization in the presence of vinyl iodoacetate

Domenii publicaţii > Chimie + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: M. Teodorescu

Editorial: Elsevier, European Polymer Journal, 37, p.1417-1422, 2001.

Rezumat:

(Vinyl acetate)-terminated polystyrene macromonomers (VAc-PSt-I) were synthesized by free-radical polymerization of styrene in the presence of vinyl iodoacetate (VAcI) as a chain transfer agent. Macromonomers with functionality close to unity were obtained, which were characterized by 1H NMR and size exclusion chromatography (SEC). No branching or incorporation of VAcI was noticed. The chain transfer constant of VAcI was determined by an integral method (Ctr = 0.46). Attempts to copolymerize the VAc-PSt-I macromonomer with VAc failed due to the involvement of the iodine end-groups in chain transfer processes, which led to the fast formation of polystyryl radicals with a very low reactivity for VAc. The replacement of the iodine atoms by azido groups allowed for the copolymerization to be carried out successfully. The formation of the graft copolymer was proved by SEC and 1H NMR measurements. It was found that the reactivity of the macromonomer is practically equal to that of VAc monomer (1/rVAc = 1.07).

Cuvinte cheie: vinyl iodoacetate, free-radical polymerization, chain transfer agent, macromonomer, styrene, vinyl acetate