Highly dispersible ternary composites with high transparency and ultra low dielectric constants based on hyperbranched polyimide with organosilane termini and cross-linked polyimide with silica

Abstract

Flexible insulating materials that are both thermally and mechanically stable, highly transparent, and have low dielectric constants are highly desirable for electronic applications. With these technical needs, a highly disperse inorganic matrix is the most important factor in polyimide-inorganic composites. We report an optimised method for the preparation of a hyperbranched polyimide using HBPI BPADA-TAP(Si) .This method involves modifying the polymer termini by coupling (3-isocyanatopropyl)triethoxysilane to HBPI BPADA-TAP(OH) via the hydroxyl (-OH) groups at peripheral positions of the polymer chain. Then, based on the HBPI BPADA-TAP(Si) with silane-modified termini, linear PI 6FDA-APB(Si) and tetraethoxysilane cross-linking agent were used to prepare ternary composites, PI 6FDA-APB(Si) _HBPI BPADA-TAP(Si) _SiO 2 , by sol-gel cross-linking reaction. The dielectric constant (D k ) of PI 6FDA-APB(Si) _HBPI BPADA-TAP(Si) -30%_SiO 2 -20% was very low, 2.04, and the optical transparencies of the ternary hybrid composite films also improved over those of similar composites due to the synergistic interactions between HBPI BPADA-TAP(Si) and PI 6FDA-APB(Si) that improves phase dispersion. The highest transparency, 95% at 450 nm, was obtained for PI 6FDA-APB(Si) _HBPI BPADA-TAP(Si) -30%_SiO 2 -20%, a significant improvement from that (87%) of the binary composite of PI 6FDA-APB(Si) _SiO 2 -20%. The glass transition temperature (T g ) of PI 6FDA-APB(Si) _HBPI BPADA-TAP(Si) -30%_SiO 2 -20% is 212.6 C, which is the highest in the ternary composite series. PI 6FDA-APB(Si) _HBPI BPADA-TAP(Si) -40%_SiO 2 -20% has the largest storage modulus, 2952.0 MPa at 180 C. The tan d values of the composite films decreased from 0.96 to 0.73 with increasing HBPI BPADA-TAP(Si) content. The ternary hybrid composites with densely cross-linked SiO 2 covalent networks developed in this study have improved dielectric, optical, thermal, and mechanical properties.Our fabrication method paves the way to the facile production of high-performance flexible and transparent electronic circuits that could be used in a broad range of applications in future electronics.RSC Adv., 2015, 5, 98419-98428 | 98419 RSC Advances PAPER The hybrid ternary composites with different compositions were prepared by a similar method, that is, by adjusting the composition of PI 6FDA-APB(Si) and silica. The lm formation property of the hybrid ternary composites depended on the contents of the HBPI BPADA-TAP(Si) and TEOS. By using the linear PAA (Si) and silane terminated hyperbranched polyimide, the hybrid ternary composites were successfully prepared. The lms are labelled as SD-2 to SD-5 (PI 6FDA-APB(Si) _HBPI BPADA-TAP(Si) -10-98420 | RSC Adv., 2015, 5, 98419-98428This journal is © The Royal Society of Chemistry 2015 RSC Advances PaperScheme 1 Synthetic route for the PI 6FDA-APB(Si) _HBPI BPADA-TAP(Si) _SiO 2 hybrid ternary composite film.This journal is

Low Dielectric Poly(imide siloxane) Films Enabled by a Well-Defined Disiloxane-Linked Alkyl Diamine

“…37,38 Ando reported the use of the trifunctional organosilicon to prepare low dielectric cross-linked PIs with silica and ever investigated the effects of BATMS-ODPA segment in the cross-linked PIs. 39,40…”

Correlating the Molecular Structure of Polyimides with the Dielectric Constant and Dissipation Factor at a High Frequency of 10 GHz

“…Goto et al prepared a series of PIs with low D k s by introducing bulky diphenyl fluorenylidene moieties and concluded that the D k values of PIs were closely related to the imide group content (Imide%) in the repeating unit and fluorine content (F%). Based on their findings, various PIs with low D k have been reported. − Our previous works on low D k PIs also revealed that incorporation of phenylene ether and adamantyl and alicyclic units to dianhydrides and diamines could effectively decrease the D k values of PIs. − Most of the above studies focused on the development of PIs with low D k values at lower frequencies (1 kHz to 10 MHz). , However, few studies investigate the molecular structure of PIs with low D k as well as low D f . − In particular, there is no clear guideline for designing PIs with both low D k and low D f , which is very important for the emerging 5G mobile communications technology. Therefore, it is of great interest and a challenge to establish the design concept of low D k and low D f PIs.…”

Synthetic strategies for highly transparent and colorless polyimide film

“…The authors then terminally modified PI BPADA-TAP(OH) by (3-isocyanatopropyl) triethoxysilane (ICTEOS), and prepared PI 6FDA-APB(Si) -PI BPADA-TAP(Si) /SiO 2 ternary composite film (10 μm thick, SD in Figure 8) by sol-gel method. 120 The connection between terminal-modified PI BPADA-TAP(Si) and siloxane is both chemical bond, which not only makes the dispersion uniformity higher, but also improves the optical and dielectric properties of the material. The λ 0 of SD are 320-323 nm.…”