Novel hyperbranched poly(phenylene oxide)s with phenolic terminal groups: synthesis, characterization, and modification

Aromatic Hyperbranched Polymers: Synthesis and Application

“…It was found that the molecular weight and Ð of the F-hb-PPOs increased with monomer concentration and reaction time. The solubility of the Fhb-PPO was different from the hb-PPO synthesized in a previous study [200], which the authors attributed to the large number of terminal groups leading to the greater solubility of hb polymers. The DB of the F-hb-PPOs decreased from 0.63 to 0.53 as the molecular weight increased.…”

“…The resulting sulfone polymers were insoluble in all common solvents. DSC analysis of the hb poly(phenylene sulfone) polymer revealed a T g of~155 C, which was higher than for hb-PPS (T g ¼ 85 C) and lower than for the linear aromatic polysulfones, which usually show high T g values of above 200 C. The hb poly(phenylene sulfone) did not show any detectable T m due to its branched architecture.…”

“…Zhang et al [200] prepared an AB 2 monomer, namely 4-bromo-4 0 ,4 00 -dihydroxytriphenylmethane, through a modified Ullmann reaction. The monomer was treated with K 2 CO 3 or NaOH as a base and copper chloride (CuCl) as a catalyst in solvents such as DMSO or sulfolane to form hb poly(phenylene oxide)s (hb-PPOs) with phenolic terminal groups (1-47, Scheme 17).…”

“…Due to the presence of the branched structure and the large number of polar phenolic terminal groups, the resulting samples exhibited higher the monomer, hb-PPO with terminal phenolic groups (1-48, Scheme 17) was obtained. Here, the aryl bromide was replaced with aryl fluoride group because in the previous studies [200], hb-PPOs prepared from 4-bromo-4 0 ,4 00 -dihydroxyltriphenylmethane by the Ullmann reaction had some limitations such as promotion of branching via Ar-CH 3 groups during high temperature processing by the unreacted amine and copper salts and also difficulty in removal of copper salts [202]. Hence, the aromatic nucleophilic substitution reaction was used to replace the Ullmann reaction to synthesize hb-PPO free of the amine and copper salts for environmental safety.…”

“…For polymers to be used for optoelectronic application a metal-free reaction for curing is the preferred route because the removal of the Cu residues after click coupling of alkyne-azide moieties using Cu(I) catalyst is quite difficult, and small residues might be detrimental for a material to be used in microelectronic applications. Again, high temperatures for curing, such as above 200 C, should be avoided because of potential degradation of some active substances. In this regard, a small molecule, namely 1,3,5-tris (azidomethyl)benzene (TAMB), was prepared by Pötzsch and Voit [233] and successfully used to crosslink the hb-PPh matrix both thermally and photochemically.…”