An initiation system of the anionic polymerization, intended for the syntheses of homopolymers and block copolymers with narrow molar mass distribution, was tested with styrene and isoprene. The actual initiating species, viz., the oligomeric α‐methylstyryl anion, originates by the reaction of n‐butyllithium with α‐methylstyrene in a benzene/diethyl ether 1:1 (v:v) solvent mixture at room temperature. The homopolymers and two‐block copolymers of styrene and isoprene, prepared by using this system, were characterized by light scattering, membrance osmometry, GPC, and 1H NMR spectroscopy. By using the suggested initiation system, it is possible to synthesize well‐defined homopolymers and block copolymers with low polydispersity (as judged by the shape of the GPC peaks and by the values of the polydispersity index), especially in a molar mass region between 4 × 104 and 1.5 × 105 g/mol. Above the upper limit of this interval, an appropriate decrease of the diethyl ether/benzene volume ratio is recommended, though the polymerization time must then be prolonged.
Three types of low-molecular-weight polybutadienes (bearing no or primary or secondary
hydroxy groups on both chain ends), as well as their hydrogenated analogues, were studied by 1H NMR
and IR spectroscopies and by dynamic light scattering. In bulk and at room temperature, hydroxylated
polymers form hydrophilic microdomains (knots) based on hydrogen bonds between two or more OH end
groups; these knots gradually disintegrate with increasing temperature and above 100 °C, only OH/OH
pairs can be present, as is seen from IR spectra. Fixation of more than two chain ends in a single knot
leads to the spatial restriction of the segmental motion of the chain links which manifests itself by the
broadening of 1H NMR bands. With unsaturated, hydroxylated polymers, an intramolecular interaction
between an OH end group and the adjacent CC bond of the terminal monomer unit is possible which
makes the formation of the intermolecular OH/OH bonding less probable. The dynamic light scattering
method revealed the presence of large clusters in bulk; these supramolecular structures are bound together
not only by hydrogen bonds but also by interactions between the aliphatic chains. With increasing
temperature, intermolecular hydrophobic domains dissociate only for unsaturated polymers.
An antioxidant derivative, 6-sulfanylhexyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, was synthesized and examined. With a radical initiator, the addition of this compound to pending vinyls of OH-telechelic, low molecular weight liquid polybutadiene (LBH) was performed to various degrees of conversion to form polymeric antioxidants (PAOs) in which the phenolic moiety was separated from the main chain by a spacer [OCH 2 CH 2 OSO (CH 2 ) 6 OOOCOO]. Pure, unstabilized LBH was mixed in several ratios with PAOs, Irganox 1520, and Irganox 1076, and the oxidation stabilities of these mixtures, determined by thermogravimetric analysis and differential scanning calorimetry, were compared. Probably because of their good compatibility with LBH, PAOs exhibited equal or better effectiveness than commercial antioxidants of the Irganox type.
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