Low-k and UV shielding polybenzoxazine nanocomposites synthesised from quinoline amine and bio-silica

Abstract

ABSTRACT Polybenzoxaines nanocomposites with low-k and UV shielding behaviour have been developed using a new bis(quinoline amine), cardanol and biosilica. The new bis(quinoline amine) was synthesized through acid catalysed Friedlander reaction and its molecular structure has been confirmed using FT-IR and 1H NMR. The bio-benzoxazine (C-bqa) was synthesised using cardanol, bis(quinoline amine) and paraformaldehyde at appropriate experimental conditions, and its molecular structure was confirmed from spectral analysis. Cardanol-based polybenzoxazine was reinforced with varying weight percentages of (5, 10, 15 wt%) of 3-glycidoxypropyltrimethoxysilane (GPTMS) functionalized bio-silica and were characterized using DSC, TGA, XRD, SEM and TEM. From the DSC analysis, it was observed that an exothermic peak maxima representing the ring opening polymerisation (curing) temperature of both neat cardanol based benzoxazine and 15 wt% of bio-silica reinforced cardanol-based benzoxazine composites are observed at 206°C and 216°C, respectively. The value of water contact angle of poly(C-bqa) was enhanced according to the increasing weight percentage of bio-silica reinforcement and the values observed for poly(C-bqa) matrix and 15 wt% of bio-silica reinforced poly(C-bqa) composites are 92° and 124° respectively. The values of dielectric constant obtained for neat poly(C-bqa) matrix and 15 wt% bio-silica reinforced poly(C-bqa) composites are 4.3 and 2.3 respectively. The UV shielding behaviour of bio-silica reinforced polybenzoxazine composites was also studied by UV-Vis spectroscopy technique and the results obtained infer that these materials possess good UV shielding behaviour.