Synthesis and gas transport properties of ODPA–TAP–ODA hyperbranched polyimides with various comonomer ratios

Synthesis and properties of hyperbranched polyimides from A2+ B′B2 monomers and A2+ B′B2 + B2 monomers with various comonomer ratios

“…By changing the molar ratio of the TAP and ODA we can easily control the number of linear units and the degree of branching. [25] No gel formation was observed during polymerizations, probably due to reduced reactivity of the TAP amino group in position 2 [19].…”

“…The results show the BPDA-TAP-ODA hyperbranched polyimides exhibited higher thermal stability than BPDA-TAP hyperbranched polyimides. It because that higher number of ODA comonomer increases distances among branched and thus afford more flexibility in relatively rigid branched structure and finally they could increase a number of chain physical entanglements [25]. The amine-terminated polyimides showed higher thermal stabilities compared with the corresponding anhydrideterminated ones, which can be attributed to the different terminal functional groups and the anhydride residues.…”

Aromatic Hyperbranched Polymers: Synthesis and Application

“…The amino-and anhydride-terminated hb-PIs showed T d,10% values of 568-583 C, indicating high thermal stability. The BTDA-and ODPA-based hb-PIs showed high T g values of 311-339 C. The [136,137,145] Dianhydrides as A2 monomers: ) and 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 1-24, Scheme 9b) as A 2 monomer to form fluorinated hb-PIs by the A 2 + B 3 approach. Here, 3,5-ditrifuoromethylphenyl was used as an end-capping reagent.…”

“…The authors attributed the high DB to the activation or deactivation of different reaction sites as a result of different electron densities caused by different substituents formed during the course of the reaction in both melt and solution. Thermal analysis indicated that the hb polyesters were amorphous in nature in contrast to the linear analog poly(mhydroxybenzoate), which is semicrystalline with a T g of 145 C and a melting point T m of 183 C [58]. Previously, Schmaljohann and coworkers [109,110] used quantitative NMR to analyze the kinetics of the melt polycondensation of 3,5-bis(trimethylsiloxy)benzoyl chloride in detail using the contents of different structural units at different degrees of conversion.…”

“…The monomer combination of A 2 + B 3 monomers is shown in Table 3, entry 3. The reaction temperature of most experiments was kept at [140][141][142][143][144][145] C to allow for a comparison with the experiments performed in DMSO and to keep minimum chain scission. The silyl method required longer reaction times than the standard method because the concentration of active end groups (phenoxide ions activated by K 2 CO 3 ) was significantly lower when silylated monomers were used.…”