Solid‐state polymerization of acenaphthylene induced by ionizing radiation

Abstract

The polymerization and copolymerization of acenaphthylene in solution or melt nitiate d by free-radical, ionic, and Ziegler catalysts have been reported in the literature.l-12 Acenaphthylene is a yellow crystalline material (m.p. 92OC.) having the following structure:This material offers interesting possibilities as a monomer for solid-state polymerization studies. The polymerization reaction should be capable of being initiated readily and most advantageously by irradiation techniques.The polymerization of acenaphthylene in the solid state initiated by x-rays has been undertaken in air, under nitrogen, and in vacuum. Both commercial and recrystallized acenaphthylene have been used. A General Electric Maxitron 250 was employed as the x-ray source; no filtration was used. Acenaphthylene was irradiated in tablet form (diameter, 2.83 cm.; thic!cness, 0.14 cm.; approximate weight 1 g.), placed at a distance of 5 cm. from the target to the top of the tablet. Different dose rates were obtained by varying the current (6-30 ma., 250 Itvp). Dose rates were calculated from Fe++-Fe3+ dosimetry, the size, thicltness, and density of the samples being taken into consideration. Dose rates of 0.824.1 x 106 rad/hr. were employed. The results are summarized below. I. Total Dose Dependence(A dose rate of 4.1 x 106 rad/hr. was employed. Two series of experiments were carried out. In the first, acenaphthylene as received (Columbia Southern) was polymerized a t ambient temperature (2535°C.) in air. The results show (upper curve, Fig. 1) that the per cent polymerization versus total dose after an induction is directly porportional to the total dose. I n the second series of experiments, acenaphthylene as received waa recrystallized twice from methanol. It was then polymerized under

Solid-state polymerization induced by radiation

“…A number of recent reviews have been largely concerned with the chemical processes involved in solid-state polymerization (Charlesby 1960, Magat 1959, 1962a, b, Bennett and Fydelor 1962, A.E.R.E. Report 3950, Chapiro 1962, USAEC TID 7643, 1963, 1964b, 1964.…”

On the instability of polyacenaphthylene in solution

“…Thus, in t h e DCE system, i t w a s possible to reach a n equilibrium state after sufficiently long periods. In Figure 5 Polyacenaphthylene is known to undergo degradation under various conditions, and studies have been reported on thermal (4,5), anionic ( 6 ) and recently also on photodegradation ( 2 ) . Dilute solution properties of PAcN in several solvents, at or near room temperature have been studi e d (3,7,8) and although c h a n g e s i n properties have been noted they were small and slow enough in these dilute systems to be ignored.…”