Crosslinkable fluorinated hyperbranched polyimide for thermo-optic switches with high thermal stability

Fluorinated Linear Copolyimide Physically Crosslinked with Novel Fluorinated Hyperbranched Polyimide Containing Large Space Volumes for Enhanced Mechanical Properties and UV-Shielding Application

Fluorinated hyperbranched polyimide (FHBPI), a spherical polymer with large space volumes, was developed to enhance fluorinated linear copolyimide (FPI) in terms of mechanical, UV-shielding, and hydrophobic properties via simple blend and thermal imidization methods. FPI possessed superior compatibility with FHBPI, and no obvious phase separation was found. The incorporation of FHBPI led to the formation of physical crosslinked network between FPI and FHBPI, which markedly improved the mechanical properties of the FPI, resulting in maximum enhancement of 83% in tensile strength from 71.7 Mpa of the pure FPI to 131.4 Mpa of the FPI/FHBPI composite film containing 15 wt % of FHBPI. The introduction of FHBPI also changed the surface properties of composites from hydrophilicity to hydrophobicity, which endowed them with outstanding dielectric stability. Meanwhile, the thin FPI/FHBPI composites kept the high transparency in the visible spectrum, simultaneously showing enhanced UV-shielding properties and lifetimes under intense UV ray. This was attributed to the newly formed charge transfer complex (CTC) between FHBPI and FPI. Moreover, the FPI/FHBPI composites possessed preeminent thermal properties. The properties, mentioned above, gave the composites enormous potential for use as UV-shielding coatings in an environment filled with high temperatures and strong ultraviolet rays.

Dispersed-Monolayer Graphene-Doped Polymer/Silica Hybrid Mach-Zehnder interferometer (MZI) Thermal Optical Switch with Low-Power Consumption and Fast Response

This article demonstrates a dispersed-monolayer graphene-doped polymer/silica hybrid Mach-Zehnder interferometer (MZI) thermal optical switch with low-power consumption and fast response. The polymer/silica hybrid MZI structure reduces the power consumption of the device as a result of the large thermal optical coefficient of the polymer material. To further decrease the response time of the thermal optical switch device, a polymethyl methacrylate, doped with monolayer graphene as a cladding material, has been synthesized. Our study theoretically analyzed the thermal conductivity of composites using the Lewis-Nielsen model. The predicted thermal conductivity of the composites increased by 133.16% at a graphene volume fraction of 0.263 vol %, due to the large thermal conductivity of graphene. Measurements taken of the fabricated thermal optical switch exhibited a power consumption of 7.68 mW, a rise time of 40 μs, and a fall time of 80 μs at a wavelength of 1550 nm.

Novel fluorinated hyperbranched polyimides with excellent thermal stability, UV-shielding property, organosolubility, and low dielectric constants

A novel fluorinated aromatic triamine, named 1,3,5-tris (4-(2-trifluoromethyl-4-aminophenoxy)phenyl) benzene (TTFAPOPB), with several –CF3 groups, prolonged chain segments, and ether bonds was first successfully synthesized via a three-step reaction. Then a series of fluorinated hyperbranched polyimides (FHBPIs) with terminal amino or anhydride groups were prepared by condensation polymerization, which were derived from three commercial dianhydrides and the obtained triamine. The prepared FHBPIs showed excellent optical properties with the transmittance reaching 94.5% at 800 nm, favorable ultraviolet (UV)-shielding property with only 27% photodegradation of methylene blue solution after intense UV irradiation for 50 min, good thermal stability with glass transition temperature between 225°C and 264°C, and 10% weight loss temperature of 520–555°C and 509–541°C, respectively, in nitrogen and air atmosphere. They also exhibited relatively good mechanical properties with tensile strength, tensile modulus, and elongation at break values of 64.2–84.2 MPa, 1.2–1.5 GPa, and 6–10%, respectively. Moreover, the introduction of –CF3 and hyperbranched architecture reduced the dielectric constants of the FHBPIs to 2.69–2.92 and increased the surface contact angles to more than 98°. Thus, the FHBPIs are promising dielectric or UV-shielding materials.

Effect of fluoro-polycarbonates containing aliphatic/aromatic segments on the characteristics of thermo-optic waveguide devices

A series of photoresists was prepared to investigate the effects of flexibility on the properties of thermo-optic waveguide devices.

Study of thermal decomposition kinetics for polyimides based on 2,6-bis(4-aminophenyl)-4-(4-(4-aminophenoxy) phenyl) pyridine

This study reports on the preparation and thermal decomposition kinetics of a polyimide (PI) with phthalimide pendant (PI-1) and an analogous hyperbranched PI (PI-2). PI-1 was synthesized from 2,6-bis(4-aminophenyl)-4-(4-(4-aminophenoxy) phenyl) pyridine (BAAP) and 4,4′-(hexa-fluoroisopropylidene) diphthalic anhydride using a simple method with BAAP terminated by phthalic anhydride. The morphology of the PI structures was examined using X-ray diffraction. The thermal decomposition processes of the PIs were then studied according to a two-stage method using thermogravimetric analysis. The results indicated that both PIs exhibited excellent thermal stability, with a decomposition pattern of 5% mass loss beyond 508°C and 10% beyond 529°C. The two PIs exhibited similar levels of thermal stability in the first decomposition stage, but PI-1 exhibited higher stability in the second stage. The results indicate that PIs into which phthalimide pendants have been introduced retain their thermal stability in the first stage of decomposition and demonstrate enhanced thermal stability in the second stage.