Two‐step route polycondensation for polynaphthalimides synthesis through high molar mass soluble precursors: A kinetic study

Abstract

Research of polynaphthalimides (PNI) frequently reports difficulties over synthesis and processing due to insolubility. In this work, we present a novel comprehensive study on the effects of time, temperature and catalyst on the synthesis of soluble PNI precursors—polyamic acids (PAAs)—, as well as a novel synthetic procedure for the synthesis of PNI using mild conditions. Kinetic studies concerning the monomer conversion and the degree of premature imidization were performed through proton nuclear magnetic resonance and gel permeation chromatography for temperature ranging from 25 to 100°C. High temperatures (above 60°C) entail extensive premature imidization and insolubility. The use of triethylamine also catalyzes imidization. At the optimal condition, soluble PAA precursors for PNI of 72 kDa could be obtained at 40°C in N‐methyl‐2‐pyrrolidone solution (30 wt%) after 5 hr polymerization.

Transparent and highly organosoluble aromatic polyimides with twisted backbone and bulky side substituents for flexible substrate materials

“…As shown in Scheme 2, the PIs were prepared by the reaction between diamine PAPNT/PAPOT and equal molar dianhydride BPDA/OPDA via a two‐step method in m‐cresol using isoquinoline as catalyst. In contrast to the one‐step polymerization approach, the novel two‐step imidization method offers the advantage of producing high‐molecular‐weight poly(amic acid) (PAA) precursors under reduced temperature 45–47 . This advancement allows the subsequent cyclodehydration of PAA to occur at a lower temperature of approximately 200 °C.…”

“…In contrast to the one-step polymerization approach, the novel two-step imidization method offers the advantage of producing high-molecular-weight poly(amic acid) (PAA) precursors under reduced temperature. [45][46][47] This advancement allows the subsequent cyclodehydration of PAA to occur The data of inherent viscosities, number-average (M n ) and weight-average (M w ) molecular weights as well as PDIs of these PIs are listed in Table 1. The obtained PIs show the inherent viscosities in the range of 0.41-0.67 dL g À1 in DMAc at 30 C, indicating that polymers have eligible molecular weights.…”