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

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.

Transparent, High Glass-Transition Temperature, Shape Memory Hybrid Polyimides Based on Polyhedral Oligomeric Silsesquioxane

“…Compared with 6FDA, aromatic dianhydride PMDA endowed PI with better thermal stability, while the transmittance decreased by about 50% at 450 nm simultaneously [32]. By contrast, incorporating inorganic materials improved the thermal stability and minimally affected the optical transparency of the PI [33,34]. These inorganic materials mainly include organoclay and polyhedral oligomeric silsesquioxane (POSS).…”

The Future of Neuroscience: Flexible and Wireless Implantable Neural Electronics

“…Target tissue Fabrication Layer thickness [µm] Transparency Hydrophobicity Parylene-C 2.75 [ 370] Rat motor cortex, [ 229] mouse visual cortex [4] Vapor deposition [ 371] 0.04-83 [ 372] 94.7% optical transmittance [ 230] Super hydrophobic [ 262] PDMS 3 × 10 −4 − 1 × 10 −3 [ 373] Mouse hippocampus, [ 234] rat sciatic nerve [ 374] Vacuum plasma system [ 179,375] 40 [ 179] Optically clear [ 376] High [ 376] Polyimide 2.5 [89] Rat cortex, [ 110] mouse brain surface [ 256] Spin coating and curing [ 377] 1-5 [ 378] Obviously transparent, transmitted above 370 nm [ 379] 82° [ 380] therefore not hydrophobic since < 90° [ 381] BCB 1.9 [ 382] Rat cortex [ 383] Spin coating, followed by reactive ion etch or E-beam [ 248] 20 [ 248] Transmittance of 70-80% in optical range [ 384] Yes [ 162] COP 2.6-3.2 [ 385] Rat somatosensory cortex [ 151] CO 2 laser [ 151] 13-188 [ 151] 7 [ 386] 91% [ 385] High between 300 and 1200 nm [ 386] 88° [ 387] SU-8 3 [ 388] Mouse somatosensory cortex [ 182] Spin coating and curing [ 159] 0.9 [ 159...…”

A Study on the Interfacial Compatibility, Microstructure and Physico-Chemical Properties of Polyimide/Organically Modified Silica Nanocomposite Membrane

“…Polyimide (PI) materials exhibit outstanding physico-chemical, electrical, and mechanical properties that allow them to be used in several advanced applications such as microelectronic, packaging, and separation [1][2][3][4][5][6][7][8]. Among polymers, particularly, PIs are a very important class of polymers because the organic segments of these polymers can easily be changed in length, rigidity, geometry of substitution, and functionality so that the Polymers 2021, 13, 1328 2 of 11 overall properties such as transparency, thermal and mechanical, compatibility, processability, dielectric constant, and chemical resistance can easily be tuned [9][10][11].…”