Preparation And Properties Of Benzoxazine Based On Aminopropyl-terminated Siloxane

Four benzoxaines, 1,3-bis(3-(2H-benzo[e][1,3]oxazin-3(4H)-yl)propyl)-1,1,3,3-tetramethyldisiloxane(P-aptmds), α,ω-bis((3-(2H-benzo[e][1,3]oxazin-3(4H)-yl)propyl)polydimethylsiloxane(P-appdms), 1,3-bis(3-(8-allyl-2H-benzo[e][1,3]oxazin-3(4H)-yl)propyl)-1,1,3,3-tetramethyldisiloxane(oAP-aptmds), and α,ω-bis(3-(8-allyl-2H-benzo[e][1,3]oxazin-3(4H)-yl)propyl)polydimethylsiloxane(oAP-appdms) were synthesized from 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane(APTMDS), α,ω-bis(3-aminopropyl)polydimethylsiloxane(APPDMS), phenol, o-allylphenol and formaldehyde. The chemical structures of the four benzoxaines were confirmed by nuclear magnetic resonance(1H, 13 C, 29 Si NMR) spectroscopy and Fourier transform infrared(FTIR). The thermally activated polymerization behaviors of the four benzoxaines were investigated by FTIR, solid-state 13 C NMR, and differential scanning calorimetry(DSC). The dynamic mechanical properties of the resultant four polybenzoxaines were determined by dynamic mechanical analysis(DMA). Thermal degradation behaviors of the four polybenzoxaines were studied by thermogravimetry(TG) and FTIR. The shape memory behaviors were studied by DMA under tension mode and bending test.FTIR spectra show that the intensities of the peaks related to the oxazine ring decreased gradually and some of the absorption peaks disappeared in the polymerization reaction whereas the peaks related to the allyl in oAP-aptmds and oAP-appdms did’t disappear completely. The polymerization peak temperatures of P-aptmds, P-appdms, oAP-aptmds and oAP-appdms are 219, 237, 215 and 234°C, respectively. The DMA results show that the glass transition temperatures(Tgs) of poly(P-aptmds), poly(P-appdms), poly(oAP- aptmds) and poly(oAP-appdms) were 110, 50, 20 and-35°C, respectively. The TG results show that the char yields of poly(P-aptmds), poly(P-appdms), poly(oAP-aptmds) and poly(oAP-appdms) are 14.84%, 22.19%, 24.7% and 26.3% at 800°C in nitrogen, respectively. The tensile stress–strain test show that the shape fixity ratios of poly(P-aptmds), poly(P-appdms) and poly(oAP-aptmds) are 71.4%, 62.9% and 96.5% and the shape recovery ratios are 57.1%, 77.1% and 79.6%, respectively.The P-aptmds and oAP-aptmds were blended with epoxy resin(oAP-EP) in different mass ratios, respectively. The DMA show that the storage modulis, the Tgs and the char yields at 800°C in nitrogen of poly(P-aptmds/oAP-EP) and poly(oAP-aptmds/oAP-EP) are higher than those of the neat polybenzoxazines. The bending test shows that the shape recovery ratios of poly(P-aptmds/oAP-EP) and poly(oAP-aptmds/oAP-EP) are 100%.