Preparation and Characterization of Transparent Polyimide⁻Silica Composite Films Using Polyimide with Carboxylic Acid Groups.

Kwan Moon,Young Jung,Ki Kim,Seung Lee,Boknam Chae

doi:10.3390/polym11030489

Abstract

Polyimide (PI) composite films with thicknesses of approximately 100 µm were prepared via a sol–gel reaction of 3-aminopropyltrimethoxysilane (APTMS) with poly(amic acid) (PAA) composite solutions using a thermal imidization process. PAA was synthesized by a conventional condensation reaction of two diamines, 3,5-diaminobenzoic acid (DABA), which has a carboxylic acid side group, and 2,2′-bis(trifluoromethyl)benzidine (TFMB), with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) in N,N-dimethylacetamide (DMAc). The PAA–silica composite solutions were prepared by mixing PAA with carboxylic acid side groups and various amounts of APTMS in a sol–gel process in DMAc using hydrochloric acid as a catalyst. The obtained PI–silica composite films showed relatively good thermal stability, and the thermal stability increased with increasing APTMS content. The optical properties and in-plane coefficient of thermal expansion (CTE) values of the PI–silica composite films were investigated. The CTE of the PI–silica composite films changed from 52.0 to 42.1 ppm/°C as the initial content of APTMS varied. The haze values and yellowness indices of the composite films increased as a function of the APTMS content.

Highlights

To serve as flexible organic electronic device substrates, polymer materials should possess high gas barriers, flexibility, toughness, processability, thermal stability and chemical resistance [1,2,3].Of the many available organic polymer materials, polyimides (PIs) have been widely used in the electronic device industry due to their excellent thermal properties, such as heat resistance, high thermal degradation temperature and high glass transition temperature, as well as their electrical and mechanical properties [4,5,6,7,8]
Polyimide (PI) composite films with thicknesses of approximately 100 μm were prepared via the sol–gel process of 3-aminopropyltrimethoxysilane (APTMS) with transparent poly(amic acid)
Transparent poly(amic acid) (PAA) was synthesized by the conventional condensation reaction of two diamines, 3,5-diaminobenzoic acid (DABA) and

Summary

Introduction

Of the many available organic polymer materials, polyimides (PIs) have been widely used in the electronic device industry due to their excellent thermal properties, such as heat resistance, high thermal degradation temperature and high glass transition temperature, as well as their electrical and mechanical properties [4,5,6,7,8]. Several concepts to create colorless PI films have recently been proposed that reduce charge-transfer complexation by introducing fluorine groups, asymmetrical and bulky pendent units, or alicyclic units into the polymer structure to overcome the poor optical properties of PI films [10,11,12,13,14,15,16]. To avoid the drawbacks of colorless PIs, hybridization of metalorganic compounds, which have organic ligands attached to metal atoms, such as Si, Al and Ti, with PI molecules has been introduced as a concept to obtain PIs with desirable thermal stability and chemical resistance [17,18,19,20,21,22]

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Conclusion