A Novel Diamine Containing Ester and Diphenylethane Groups for Colorless Polyimide with a Low Dielectric Constant and Low Water Absorption

Abstract

In this study, a novel diamine monomer containing ester and phenyl moieties, 1,2-diphenylethane-1,2-diyl bis(4-aminobenzoate) (1,2-DPEDBA), was synthesized through a three-step reaction. Using this diamine, a novel polyimide (PI) film was prepared with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA) as a counter dianhydride through a typical two-step chemical imidization. For comparison, poly(pyromellitic dianhydride-co-4,4′-oxydianiline) (PMDA-ODA PI) was also synthesized via thermal imidization. The resulting 6-FDA-DPEDBA PI film was not only soluble in common polar solvents with high boiling points, such as N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF), but also soluble in common low-boiling-point polar solvents, such as chloroform (CHCl3) and dichloromethane (CH2Cl2), at room temperature. The resulting novel PI showed a 5% weight loss temperature (T5d) at 360 °C under a nitrogen atmosphere. The resulting PI film was colorless and transparent with a transmittance of 87.1% in the visible light region ranging from 400 to 760 nm. The water absorption of the novel PI film was of 1.78%. The PI film also possessed a good moisture barrier and hydrophobicity. Furthermore, the resulting PI film displayed a low dielectric constant of 2.17 at 106 Hz at room temperature. In conclusion, the novel PI film exhibited much better optical transparency, lower moisture absorption, and a lower dielectric constant as well as better solubility than the PMDA-ODA PI film, which is insoluble in any solvent, although its thermal stability is not better than that of PMDA-ODA PI.

Structural Designs of Transparent Polyimide Films with Low Dielectric Properties and Low Water Absorption: A Review

“…A PI containing 1,2-diphenyl pendant groups was developed by Lee et al using novel ester-containing diamines and FDA [ 1 ]. The developed PI was highly soluble in polar organic solvents and exhibited excellent optical transmittance (T 450 : 85.57% at 450 nm).…”

“…Increasing demand for the Internet of Things (IoT) requires the development of communication technologies, such as 6G, and the further advancement of 5G communication capabilities [ 1 ]. With 5G/6G wireless technologies, connections between base stations and mobile phones/intelligent machines are more reliable, enabling faster inter-device communication [ 2 ].…”

Synthesis and properties of modified thermoplastic polyimide films with good dielectric properties at high frequency and enhanced thermal stability via incorporation of rigid ester and biphenyl structural units

“…Among various functional PIs, ester-containing PI or polyesterimide (PEsI) films have attracted increasing attentions in high-tech areas due to the high and stable electrical insulating properties, low water uptakes, good thermal stability, low CTE, and good tensile properties. [32][33][34] This is mainly ascribed to the distinctive physical and chemical characteristics of ester bonds, including rigid molecular skeleton, moderate molar polarization and molar volumes, and so on. These properties of the PEsI films are all required for the high-frequency FCCL substrates.…”

Research Advances of Porous Polyimide—Based Composites with Low Dielectric Constant

“…Figure 1 shows the preparation of a typical PI from the thermal imidization of polyamic acid (PAA) that can be obtained from pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA). Because of its good mechanical properties, thermal stability and insulation properties, PI has been widely used in aerospace, automobile, electronics and other fields [ 8 , 9 , 10 ]. Li et al [ 11 ] synthesized a PAA solution by ternary copolymerization of 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA), p-phenylenediamine (PDA) and 2,2′-bis (trifluoromethyl)-4,4′-diamino biphenyl (TFDB), and obtained PI films with uniform pores through the processes such as thermal imidization, casting and film laying.…”