Vinylpyridine Oligomers

Vinylpyridine Oligomers. Oligomerizations of 2-vinylpyridine are closely related to polymerizations of methacrylates. Products formed by initiation using lithium and sodium salts of 2-ethylpyridine in THF at —78 °C are predominantly (>95%) isotactic. Methylation of 1,3-di(2-pyridyl)butane anion with... 

Ruokolainen J, Torkkeli M, Serimaa R, Komanschek E, ten Brinke G, Ikkala O. Order-disorder transition in comblike block copolymers obtained by hydrogen bonding between homopolymers and end-functionalized oligomers poly(4-vinylpyridine)-pentadecylphenol. Mactomolecules 1997 30 2002-2007. 

Oligomers prepared by radical polymerization of 2-vinylpyridine could be separated into tactic isomers on a silica column (250 x 4.6 dQ = 10 nm dP = 10 pm) with a gradient pentane/methanol (concave 10 to 40% in 30 min). The experiments were... 

Oligomer and polymer additives with a primary or secondary amino group or with tertiary nitrogen able to bind water-soluble dyes containing acid groups, assortment palette of which is very wide. This function is fulfilled, e.g. by ethylene copolymers with alkyl amino-acrylates, vinylpyridine, N-vinylcarbazole and acrylamide, further acrylate copolymers, copolyamides with the derivatives of piperazine, polyaminotriazoles, polyureas and styrene-amine resins. They are added to PP before spinning in an amount up to lOwt.%... 

Methyl Methacrylate. The most generally usefiil initiator for anionic polymerization of MMA and related compounds is 1,1-diphenylhexyllithium which is formed by the quantitative and facile addition of butyllithium with 1,1-diphenylethylene (DPE) (eq. 17) (46). Using this initiator in THF at -78°C, it is possible to polymerize MMA to obtain polymers and block copolymers with predictable molecular weights and narrow molecular weight distributions. Controlled polymerizations are not effected in nonpolar solvents such as toluene, even at low temperatures. Other usefiil initiators for polymerization of MMA are oligomers of (a-methylstyryl)lithium whose steric requirements minimize attack at the ester carbonyl group in the monomer. These initiators are also useful for the polymerization of 2-vinylpyridine (see Methacrylic Ester POLYMERS). 

Many cereal endosperm storage proteins—especially glutelins— are, in their native forms, disulfide-bonded oligomers or polymers. Even if soluble, such proteins may resolve poorly upon RP-HPLC and elute as broad peaks [22], in part due to their many possible polymeric forms. Reduction is necessary to release disulfide-bonded subunits from cereal glutelins or oligomeric prolamins for analysis [19,32,42,76]. Thus, protein resolution, extractability, and stability are often improved by extraction under reducing conditions. To prevent reoxidation and further enhance resolution, resulting cysteine residues may be stabilized by alkylation, usually with 4-vinylpyridine [19,21,29,70,76]. 

Soum and Fontanille report that di-s-butyl magnesium generates living polymer from 2-vinylpyridine without the involvement of the side-reactions that afflict the polymerization initiated by alkali metal alkyls the resulting polymer has an isotacticity index of 0.9. Arai et al. have synthesized styrene-butadiene-4-vinylpyridine triblock copolymers. Hogen-Esch et a/. have continued their study of the stereochemistry of the anionic polymerization of 2-vinylpyridine in THF solution. Oligomers were synthesized by addition of alkali salts of 2-ethylpyridine to 2-vinylpyridine termination was effected by reaction with methyl iodide. Highly isotactic products were obtained with U and Na as counterions but with K or Rb there was no stereoselection. Epimerization resulted in the expected statistical mixtures of stereoisomers and it was concluded that stereoselection is kinetically controlled. 

We have also examined the oligomerization of alpha-methyl-2-vinylpyridine according to equation (4). Oligomers [18] are crystalline products with sharp melting points and the tetramer... 

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