engleski

Two-Dimensional Infrared Correlation Spectroscopic Study on Thermal Polymerization of Diphenylbutadiyne

Thermal polymerization of diphenylbutadiyne at atmospheric pressure was investigated by differential scanning calorimetry, thermogravimetric analysis and two-dimensional infrared (2D IR) correlation spectroscopy. Temperature induced spectral changes were monitored in the whole region 3200?400 cm-1. The spectral region 2300-2000 cm-1 of the triple bond stretching was thoroughly analyzed because it contains two bands in melt or solution of diphenylbutadiyne, at 2210 cm-1 (IR forbidden) and 2148 cm-1 (IR allowed). The two bands share a synchronous negative cross peak indicating opposite temperature-induced intensity changes. The symmetric C≡ C stretching band at 2210 cm-1 is in fact at higher temperatures superposition of similar acetylenic bands of different oligomers. The oligomers most probably have cyclic structure since the 2210 cm?1 band persists at the highest temperatures where the monomer band at 2148 cm-1 exists no more. The new ascending band at 700 cm-1 shows the strongest synchronous autopeak and is clearly associated with simultaneous decreasing of the 687 cm-1 intensity associated with phenyl ring out?of?plane deformations. In the temperature interval 90?180 °C we observe the so-called induction period consistent with the onset of the bimolecular mechanism that is most probable for the DPB polymerization at temperatures above 200 °C.

diphenylbutadiyne; diphenyldiacetylene; 2D IR correlation spectroscopy; thermal polymerization

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