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