Highly soluble polyimides from sterically hindered diamines

Design and preparation of novel fluorescent polyimides containing ortho-linked units and pyridine moieties

“….4°C (as shown in Figure 6). The high T g values might be attributed to the substitution of phenoxy units in the position ortho to an imide ring, which increasingly inhibited the rotation of the nitrogen atom along the phenyl ring, resulting in more rigid polymer chains that in turn increased the Tg values of the polymers [38,39]. In addition, the increasing order of T g generally correlated with the structure of the dianhydride component.…”

“…Recently, a novel approach to increasing solubility of PIs without sacrificing their thermal stability has been found [31][32][33]. Eastmond and others have shown that the incorporation of ortho-linked unit into the polymer backbone may interrupt the chain packing and improve the solubility [34][35][36][37][38][39]. In addition, the incorporation of ortho-linked units can induce important new properties, such as high glass transition temperature for the resulting polymers [38,39].…”

“…Eastmond and others have shown that the incorporation of ortho-linked unit into the polymer backbone may interrupt the chain packing and improve the solubility [34][35][36][37][38][39]. In addition, the incorporation of ortho-linked units can induce important new properties, such as high glass transition temperature for the resulting polymers [38,39]. As stated above, synthesizing a kind of pyridine-containing PIs with bulky pendent substituents, ortholinked unit and flexible ether linkage may be an innovative way to obtain soluble and high glass transition temperature fluorescent PIs.…”

Synthesis and Thermal Properties of Main Chain Polyimides Containing Chalcone Derivative

“…Therefore, the structural modification such as the introduction of bulky lateral substituents, flexible alkyl side chains, bent molecules and so on is investigated to enhance the solubility and the processability of the polyimides. [25][26][27][28][29][30] Figure 1 displays the chemical structures of chalcone-based polyimides synthesized. The synthesis of the diamine derivatives was described in Schemes 1 and 2.…”

Synthesis and characterization of novel aromatic polyimides from 4,4-bis(p-aminophenoxymethyl)- 1-cyclohexene

“…For example, we reported the effects of backbone modification on polymer properties involving incorporation of hindered diamines (blocking rotation around the C-N bond) and substituted hydroquinone-based ether diamines (blocking rotation around the inner C-O bond). 13,14 The former approach had significant impact on solubility with less property compromise. The latter approach did not show a dramatic solubility enhancement with trimethylhydroquinone 14 and 2,5-di-t-butylhydroquinone 15 segments, apparently due to segmental rigidity and strong interchain interactions.…”