A non-porous and amorphous fluoropolymer PFN with low dielectric constant of 2.33 and dielectric loss less than 1.2 × 10(-3) is reported here. PFN also exhibits good mechanical properties and high thermostability. This study is a new example of a fully dense material showing a low k value and having good thermo/mechanical properties.

A novel functional oligomer (Si-TFVE) with a siloxane backbone and thermally cross-linkable trifluorovinyl ether groups (−OCFCF 2 ) is reported here. When postpolymerized at high temperature, Si-TFVE converts to an amorphous cross-linked network (Si-PFCB), which shows a dielectric constant of 2.33 and dielectric loss below 2.1 × 10 −3 at 30 MHz. Si-PFCB also shows excellent film uniformity with the surface roughness less than 5.79 nm over a 1 μm square area. Moreover, Si-PFCB shows high thermostability with a 5 wt % loss temperature of 472 °C and no obvious T g below 350 °C. In regard to the mechanical properties, Si-PFCB has Young's modulus, hardness, and bonding strength with silicon wafer surface of 10.06 GPa, 0.392, and 4.93 GPa, respectively. These results suggest that such oligomer is suitable for utilization in ultralarge scale integration circuits. In addition, this contribution provides a new route to prepare cross-linked organosiloxanes only by heating instead of using catalysts or initiators in the traditional procedures.

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A new benzocyclobutene monomer with a fluorene backbone was synthesized, which can be thermally converted to a cross-linked network with low dielectric constant and high thermostability.

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Abstract:The effects of different lightweight functional fillers on the properties of cement-based composites are investigated in this study. The fillers include fly ash cenospheres (FACs) and glass micro-spheres (GMS15 and GMS38) in various proportions. The developed composites were tested for compressive, flexural and tensile strengths at 10 and 28-day ages. The results indicated that both FACs and GMS38 are excellent candidates for producing strong lightweight composites. However, incorporation of GMS15 resulted in much lower specific strength values (only up to 13.64 kPa/kg m 3 ) due to its thinner shell thickness and lower isostatic crushing strength value (2.07 MPa). Microstructural analyses further revealed that GMS38 and GMS15 were better suited for thermal insulating applications. However, higher weight fraction of the fillers in composites leads to increased porosity which might be detrimental to their strength development.

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