High-pressure synthesis and optical limiting property of cyclic diphenylacetylene oligomer

Abstract

New conjugated oligomers were synthesized by reacting diphenylacetylene under high pressure of 0.13–0.76 GPa at 250 and 300°C for 1–10 h. The number-average molecular weight Mn, and the weight-average molecular weight Mw increased with pressure, but those values were independent of temperature and time (Mn, 320–490; Mw, 350–580). Elementary analysis, field desorption mass spectrometry, Fourier transform infrared, and 13C nuclear magnetic resonance experiments revealed that the oligomer above and including pentamer was a new compound having cyclic structure. Toluene solutions of the oligomer (400 Mn) contained within a quartz cell were irradiated with the pulse from a frequency-doubled Nd : Yag laser at 532 nm. The transmittance of the solution decreased with input fluence, and we observed an optical limiting property with saturated output fluence. As the concentration of the oligomer increased, the saturated output fluence decreased. The optical limiting property was analyzed according to the reverse saturable absorption mechanism. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:129–135, 1998