Synthesis of well‐defined functionalized polymers and star branched polymers by means of living anionic polymerization using specially designed 1,1‐diphenylethylene derivatives

This article covers precise syntheses of well‐defined chain‐end and in‐chain functionalized polymers, multi‐functionalized polymers with a definite number of functional groups, star‐branched and graft polymers by recently developed methodologies using specially designed 1,1‐diphenylethylene (DPE) derivatives. The DPE derivatives include various substituted DPE derivatives with functional groups and their derivatives, DPE‐functionalized DPE derivatives, and well‐defined DPE‐functionalized macromonomers. The synthetic utility and importance of these DPE derivatives are described via such polymer syntheses.     

Synthesis of branched polymers by means of anionic polymerization. 11. anionic synthesis of densely branched polystyrenes carrying double branches in each repeating unit

We have demonstrated the first successful synthesis of well-defined densely branched polystyrenes carrying double branches in each of all repeating unit of backbone polymer by the coupling reaction of 1,1-diphenylethylene-end-capped polystyryllithiums with novel polystyrene derivatives having two benzyl bromide moieties in each monomer unit. The coupling reaction efficiently and quantitatively proceeded without any steric limitations to introduce two polystyrene branches in each repeating unit under certain conditions in THF at −40°C. Thus, a series of 36.4- and 181-arm densely branched polystyrenes were synthesized (M_w = 365 ∼ 2 000 kg/mol, M_w/M_n = 1.01 ∼ 1.03). In the 36.4-arm branched polystyrenes thus synthesized, the maximum M_w value of the introduced polystyrene as a branch segment was 55.1 kg/mol. The experimental g‘ values of the 36.4-arm branched polystyrenes deterimined in the range of 0.14 ∼ 0.15 were very close to the value of 0.13 calculated from the empirical equation previously reported by Roovers.     

Synthesis and surface characterization of novel perfluorooctyl-functionalized polymers with well-defined architectures

We have successfully synthesized two kinds of novel well-defined chain-end-functionalized polystyrenes with one, two, three, and four perfluorooctyl (C₈F₁₇) groups and structurally analogous block copolymers, poly[styrene-b-4-(3-perfluoroocyl)propoxystyrene], by means of living anionic polymerization, followed by the Williamson reaction with C₈F₁₇(CH₂)₃Br. The surface properties and compositions of the films prepared from both C₈F₁₇-functionalized polymers have been characterized by contact angles using water and dodecane droplets and angle-dependent XPS measurement. It was observed that C₈F₁₇ groups were segregated and preferentially enriched at their topmost surfaces and the extent of the enrichment increased with the number of C₈F₁₇ group. The dependence of extent of C₈F₁₇ group enrichment on fluorine content however appears to be different between chain-end-functionalized polymer and block copolymer.     

Selective synthesis of organic sulfides and disulfides by the reduction of elemental sulfur with samarium diiodide

Elemental sulfur can be reduced to the corresponding thiolate anion species (S²⁻ and S²⁻₂) selectively by samarium diiodide in the presence and absence of HMPA, respectively. The subsequent alkylation of the thiolate anion species provides a useful synthetic route to dialkyl sulfides and disulfides. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9: 581–584, 1998     

Dimensionally oriented redox-active π-conjugated systems

Porphyrins bearing the redox-active phenylenediamine pendant groups are synthesized to afford dimensionally oriented π-conjugated systems. The structural and electronic characteristics depend on the atropisomers. In the fluorescence emission spectra, the emission from the porphyrin moiety is almost completely quenched. Zinc complexation of the αααα isomers gives the corresponding zinc porphyrins bearing four phenylenediamine strands. Treatment with a bidentate ligand, DABCO, leads to the sandwich dimer complex, in which the porphyrin moieties are surrounded by π-conjugated pendant groups. p-t-Butylcalix[4]arenes bearing four redox-active phenylenediamine pendant groups on the lower rim are synthesized and characterized both spectroscopically and electrochemically. The interconversion of the oxidation states of the pendant groups is demonstrated both chemically and electrochemically.