Synthesis of a Novel Rigid Semi-Alicyclic Dianhydride and Its Copolymerized Transparent Polyimide Films’ Properties

Abstract

A new series of colorless polyimides (CPIs) with outstanding thermal properties and mechanical properties were fabricated by the copolymerization of a novel dianhydride and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 2,2′-bistrifluoromethyl benzidine (TFDB). The novel dianhydride, 10-oxo-9-phenyl-9-(trifluoromethyl)-9,10-dihydroanthracene-2,3,6,7-tetraacid dianhydride (3FPODA), possessed a rigid semi-alicyclic structure, –CF3 and phenyl side groups, and an active carbonyl group. Benefitting from the special structure of 3FPODA, the glass transition temperatures (Tg) of the new CPIs improved from 330 °C to 377 °C, the coefficient of thermal expansion (CTE) decreased from 46 ppm/K to 24 ppm/K, and the tensile strength (TS), tensile modulus (TM), and elongation at break (EB) increased from 84 MPa to 136 MPa, 3.2 GPa to 4.4 GPa, and 2.94% to 4.13% with the increasing amount of 3FPODA, respectively. Moreover, the active carbonyl group of the 3FPODA could enhance the CPI’s adhesive properties. These results render the new dianhydride 3FPODA an ideal candidate monomer for the fabrication of high-performance CPIs.

Colorless Poly(amide-imide)s with Low Dielectric Constants and Enhanced Mechanical Properties through Tri-Armed Cross-Linkers

“…Compared with the TMC-TFMB system, PAI-1 in this work shows worse mechanical strength and elongation at break owing to the presence of the 6FDA moiety that leads to loosened molecular chains. 38,39 PAI-1 has the lowest inherent viscosity of 0.63 and the lowest molecular weights. After cross-linking, the inherent viscosities of PAI-2 to PAI-4 increase from 0.96 to 1.24; also, the M n has a significant surge from 9.4 × 10 4 to 1.3 × 10 5 (g/mol).…”

Design, Synthesis and Properties of Semi-Alicyclic Colorless and Transparent Polyimide Films with High Glass Transition Temperatures and Low Retardation for Potential Applications in Flexible Electronics

“…The fluorene-containing CPI films show very low birefringence (Δn) values at the level of minus fourth power of ten, and further, exhibit quite low optical retardations below 10 nm. The R th values for the current fluorene-based CPI films (thickness: 10 μm) were obviously lower than those of the CPI systems reported in the literature, such as the wholly aromatic ones in [ 42 ] (R th : 114~172 nm, measured with a film thickness of 2 μm), the ones in [ 43 ] (R th : 84.5~135 nm, measured with a film thickness of 20 ± 5 μm), and the ones in [ 21 ] (R th : 42~279 nm, measured with a film thickness of 15~18 μm), and were also lower than those of the semi-alicyclic ones in [ 44 ] (R th : 276~496 nm, measured with a film thickness of 10 μm). The excellent optical properties of the current CPI films benefited partly from the fluorene substituents in the diamine units, and also from the cyclohexane structure in the dianhydride moiety.…”

Polyimides with low dielectric constants and dissipation factors at high frequency derived from novel aromatic diamines with bistrifluoromethyl pendant groups

“…Obviously, the HFBODA groups have lower λ cut and higher transmittance at 500 nm than the control groups due to the strong electron-withdrawing effect of the trifluoromethyl group. 13,36,37 Besides, the larger volume of the bis(trifluoromethyl) and isopropylidene groups would cause a larger steric hindrance, hindering the intermolecular CTC. As a result, 6FDA-HFBODA and BPADA-HFBODA exhibited good optical transparency.…”