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Condensation reaction of poly(ethylene glycol) (PEG) with a carboxyl group at one chain end and hyperbranched polyamide (HBPA) with a hydroxyl group at the focal point was performed in the presence of condensation agent at ambient temperature, yielding PEG ‐ b ‐ HBPAs with defined molecular weight and very narrow molecular weight distribution. PEG ‐ b ‐ HBPA formed micelles in water. [ABSTRACT FROM AUTHOR]

This article covers the synthesis and self-assembly of several polymer architectures containing condensation polymers with low polydispersities by chain-growth condensation polymerization utilizing substituent effects. Well-defined AB, ABA, BAB, ABC type block copolymers, star polymers, star block copolymers and miktoarm star copolymers containing aromatic polyamide or aromatic polyether as a segment were synthesized by 1) sequential addition of monomers, 2) a polymer coupling reaction, 3) a macroinitiator method with modification of polymer end group, and 4) macroinitiator method with an orthogonal initiator. Furthermore, the polymers self-assembled in a unique way. [ABSTRACT FROM AUTHOR]

In this review article, polycondensation that proceeds in a chain-growth polymerization manner ("chain-growth polycondensation") for well-defined condensation polymers are described. Our approach to chain-growth polycondensation is (1) activation of polymer end group by substituent effects changed between monomer and polymer and (2) phase-transfer polymerization in biphase composed of monomer store phase and polymerization phase. In the approach (1), a variety of condensation polymers such as aromatic polyamides, aromatic polyesters, aromatic polyethers, poly(ether sulfone), and polythiophene with defined molecular weights and low polydispersities were obtained. Their polycondensations had all of the characteristics of living polymerization: a linear correlation between molecular weights and monomer conversion maintaining low polydispersities, and control over molecular weights by the feed ratio of monomer to initiator. Taking advantage of the nature of living polymerization in this polycondensation, we synthesized diblock copolymers of different kinds of aromatic polyamides and of aromatic polyamide and conventional polymers such as poly(ethylene glycol), polystyrene, and poly(tetrahydrofuran), as well as triblock copolymers and star polymers containing aromatic polyamide units. Some copolymers were arranged in a supramolecular self-assembly. In the approach (2), the polycondensation of solid monomer dispersed in organic solvent with a phase transfer catalyst (PTC) was carried out, where solid monomer did not react with each other, and the monomer transferred to organic solvent with PTC reacted with an initiator and the polymer end group selectively inorganic solvent, to yield well-defined polyesters. [ABSTRACT FROM AUTHOR]

The article focuses on the organometallic polycondensation as a reliable method for the synthesis of polymers. The molecular weight and polydispersity of the polymers are not well-controlled due to the step-growth polymerization nature of polycondensation. The catalyst-transfer Suzuki-Miyaura coupling polymerization is investigated and it was found that dioxaborolane, with a catalytic amount of 2 through the coupling reaction, showed a narrow molecular weight distribution.

This article cites a study, which states that not only para-substituted AB-type aromatic monomers but also meta-substituted ones undergo chain-growth polycondensation by virtue of different inductive effects between monomer and polymer. This I effect- assisted polycondensation should enable us to extend the synthesis of well-defined condensation polymers from pat-a-substituted aromatic polymers to a variety of meta-substituted ones, which possess higher solubility. Furthermore, this polymerization method should be applicable to chain-growth polycondensation of even aliphatic monomers, such as amino acid and lactic acid derivatives.

Successive catalyst-transfer condensation polymerization of a Grignard-type phenylene monomer and then a thiophene monomer with a Ni catalyst yields well-defined block copolymers of poly(p-phenylene) and polythiophene, but the reverse order of polymerization results in polymers with broad molecular weight distribution. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel boron-containing compound, benzoxazaborine, was synthesized. • The obtained benzoxazaborines were reasonably stable to hydrolysis. • The oxazaborine ring was the highly planar structure. • The B N bond length indicated an extended π-conjugated system. Abstract Benzoxazaborine derivatives were synthesized by the dehydration condensation reaction of 2-aminobenzyl alcohols with arylboronic acids. The insensitivity of the benzoxazaborines to hydrolysis allowed these compounds to be isolated by silica gel column chromatography. The single crystal X-ray structural analysis demonstrated the highly planar structure of the benzoxazaborine unit, and the B N bond length indicated an extended π-conjugated system. [ABSTRACT FROM AUTHOR]

The article examines the catalyst transfer of conductive polymers with controlled molecular weight and low polydispersity. In one study, the polycondensation of a Grignard thiophene monomer with Ni-Cl2 as catalysts would proceed into a chain-growth polymerization mechanism. A monomer addition experiment was conducted to determine the chain-growth nature of the polymerization.