Preparation and characterization of polymers formed by irradiation of B-pinene and other monomers

The gamma radiation-induced cationic polymerization of β-pinene was carried out under super-dry conditions. Chemical characterization by means of nmr, ultraviolet, and infra-red spectroscopic techniques and elemental analysis showed the repeat unit to be

Photo Diagram

X-ray diffraction methods were used to obtain crystallinity data and other morphological information. . Thermal and solubility characterizations were also carried out. Auto-oxidation of the polymer resulted in the formation of peroxy and ketonic groups. . Elemental analysis was used to determine the amount of oxygen incorporated in the auto-oxidized polymer. These results are discussed in comparison to those obtained for the commercial Polyterpene Resin, prepared by Lewis acid catalysis.

Poly(β-pinene) was also prepared by thermal polymerization at 160°C. The effect of additives indicated that the mechanism involved free radical propagation. The results of the X-ray diffraction and proton nmr spectroscopy of this polymer were similar to those of the polymer prepared by gamma irradiation indicating that the same repeat unit as well as the same crystalline unit cell were present in both of these polymers.

The radiation-induced copolymerization of β-pinene with styrene and with a-methyl styrene results in the formation of copolymers which

iv are probably random. Their molecular weights were very close to those for poly(β-pinene). The mechanism for these copolymerizations has been discussed in terms of the importance of chain transfer reactions during cationic propagation.

The radiation-induced polymerization of 2,5-norbornadiene occurs four to five times faster in the solid state at -78°C than in the liquid state at ca. 250°c. In both cases the repeat unit was found to be a nortricyclene structural unit with one norbornene unit as one of the end groups of the polymer chain. At conversions greater than 19 %, the solid-state irradiations resulted in gelation. These results have been interpreted on the basis of cationic propagation and with the possibility of topochemical, crosslinking, and other reactions taking place in the case of the solid-state polymerizations.