Molecular Design of Soluble Biopolyimide with High Rigidity.

Sumant Dwivedi,Tatsuo Kaneko

doi:10.3390/polym10040368

Abstract

New soluble biopolyimides were prepared from a diamine derived from an exotic amino acid (4-aminocinnamic acid) with several kinds of tetracarboxylic dianhydride. The biopolyimide molecular structural flexibility was tailored by modifying the tetracarboxylic dianhydride moiety. The obtained polyimides were soluble in various solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, and even tetrahydrofuran. It was observed that the biopolyimide solubility was greatly dependent upon the structural flexibility (torsion energy). Flexible structure facilitated greater solubility. The synthesized biopolyimides were largely amorphous and had number-average molecular weight (Mn) in the range (5–8) × 105. The glass transition temperatures (Tg) of the polymers ranged from 259–294 °C. These polymers exhibited good thermal stability without significant weight loss up to 410 °C. The temperatures at 10% weight loss (Td10) for synthesized biopolyimide ranged from 375–397 °C.

Highlights

Aromatic polyimides (PI) have gained a reputation for exhibiting outstanding thermal behavior and have been used in a wide range of applications such as electronics, coatings, composite materials, linear and non-linear optical materials, and membranes [1,2,3,4]
Yagci and Mathias reported several kinds of polyimides synthesized from trimethyl and di-tert-butylhydroquinone-based ether-linked diamines [14]
As exprssed in Equation (1), MW is the polymer weight-average molecular weight, n is the number of aromatic carbon atoms, C is a constant dependent on the solvent and/or kind of diamine in the biopolyimide and K is the solubility inducing constant determined by a data fitting method

Summary

Introduction

Aromatic polyimides (PI) have gained a reputation for exhibiting outstanding thermal behavior and have been used in a wide range of applications such as electronics, coatings, composite materials, linear and non-linear optical materials, and membranes [1,2,3,4]. The commercial use of these materials is often limited because of the difficult and expensive processing owing to their poor solubility and high softening or melting temperatures To resolve these problems, many researchers have focused on synthesizing soluble and processable aromatic polyimides in a fully imidized form without compromising their excellent physical properties. Several synthetic modifications of basic rigid-chain structures, including the introduction of flexible linkages, bulky side substitutions, and asymmetric monomers into the backbone, have been attempted [5,6,7,8] Soluble polyimides, such as ULTEM 1000 resin, are commercially available but possess low softening temperature (217 ◦ C) accompanied by rapid thermal degradation (171 ◦ C) [9]. This article describes the synthesis of a series of biopolyimides using

Materials

Syntheses

Characterization

Results and Discussion

Conclusions