Polyimide Copolymers and Nanocomposites: A Review of the Synergistic Effects of the Constituents on the Fire-Retardancy Behavior

Abstract

Carbon-based polymer can catch fire when used as cathode material in batteries and supercapacitors, due to short circuiting. Polyimide is known to exhibit flame retardancy by forming char layer in condensed phase. The high char yield of polyimide is attributed to its aromatic nature and the existence of a donor–acceptor complex in its backbone. Fabrication of hybrid polyimide material can provide better protection against fire based on multiple fire-retardancy mechanisms. Nanocomposites generally show a significant enhancement in mechanical, electrical, and thermal properties. Nanoparticles, such as graphene and carbon nanotubes, can enhance flame retardancy in condensed phase by forming a dense char layer. Silicone-based materials can also provide fire retardancy in condensed phase by a similar mechanism as polyimide. However, some inorganic fire retardants, such as phosphazene, can enhance flame retardancy in gaseous phase by releasing flame inhibiting radicals. The flame inhibiting radicals generated by phosphazene are released into the gaseous phase during combustion. A hybrid system constituted of polyimide, silicone-based additives, and phosphazene would provide significant improvement in flame retardancy in both the condensed phase and gas phase. In this review, several flame-retardant polyimide-based systems are described. This review which focuses on the various combinations of polyimide and other candidate fire-retardant materials would shed light on the nature of an effective multifunctional flame-retardant hybrid materials.

Optical and Flame-Retardant Properties of a Series of Polyimides Containing Side Chained Bulky Phosphaphenanthrene Units

“…Polyimides, polymers with multiple commercially available representatives, continue to be a class of high-performance polymers of great interest to the scientific community [ 1 , 2 , 3 ]. These polymers are being studied more and more because of their desirable features, including outstanding thermo-oxidative stability, intrinsic flame resistance, distinct electrical characteristics, excellent radiation and solvent resistance, and good mechanical qualities [ 4 , 5 ]. Despite their unique characteristics the extensive use of fully aromatic polyimides is limited mainly due to their advanced insolubility in organic solvents [ 6 , 7 ].…”

Enhancing flame retardancy and optical functionality in multifunctional devices through advanced design of phosphorus‐containing copoly(imide‐oxadiazole)s

“…Furthermore, their inherently high thermal stability makes it challenging to bond or adhere to other materials, hindering their integration into composite structures. To overcome these limitations, researchers have been working on the modification of polyimides with various additives and copolymers 7–9 . One such modification involves incorporating oxadiazole units into the polyimide structure, 10–16 that imparts these materials with advantageous optical characteristics, making them highly desirable for a wide range of optical devices and systems 10,17 .…”

“…To overcome these limitations, researchers have been working on the modification of polyimides with various additives and copolymers. [7][8][9] One such modification involves incorporating oxadiazole units into the polyimide structure, [10][11][12][13][14][15][16] that imparts these materials with advantageous optical characteristics, making them highly desirable for a wide range of optical devices and systems. 10,17 One of the key attributes of polyimides with oxadiazole units is their excellent transparency in the visible and near-infrared regions of the electromagnetic spectrum.…”

A Study of the Degradation Mechanism of Ladder-like Polyhedral Oligomeric Silsesquioxane via Fourier Transform Infrared Spectroscopy

“…Silicone-based materials are well-known for their thermal stability. They are regarded as an environmentally friendly class of flame-retardant materials for carbon-based poly- meric materials [1][2][3][4][5][6]. The favorable heat of degradation of silicone-based materials originates at the atomistic level from the superior bond strength of the silicon-oxygen (Si-O) bond when compared to that of the carbon-carbon (C-C) bond.…”