Limonene polymers prepared

Figure 5.11 Polymers prepared in D-limonene poly(cyclopentene) (PCP), isotactic polypropylene (PP) and poly(methylphenylsilane) (PMPS).

Despite the ability of unsaturated mercaptans to give tars readily they were prepared as early as 1934 by Von Braun, who did not recognize the ability of these compounds to cyclize. Likewise photolysis of hydrogen sulfide in the presence of allyloxyethanol, " or decomposition of the adducts of thiolacetic acid with 4-vinyl-l-cyclohexene or d-limonene, gave only polymers, and no cyclized products, probably because high-dilution conditions were not used. 

Limonene can also be copolymerized with acrylonitrile (in DMF at 70°C, initiator AIBN) [69], MMA (xylene, 80°C, BPO) [70], styrene (xylene, 80°C, AIBN) [71], A(-vinylpyrrolidone (dioxane, 80°C, AIBN) [72], and (V-vinyl acetate (dioxane, 65°C, AIBN) [73], always producing alternating copolymers. Radical addition of limonene occurs via the exocyclic isopropenyl group (in contrast to the cationic system, see above). Also, a terpolymer of limonene, MMA, and styrene has been prepared by free-radical copolymerization (xylene, 80°C, BPO) [74]. Poly (limonene-co-MMA) can be converted into a LC polymer (cf. Scheme 2) [75]. 

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