Myrcene styrene block copolymer

Quirk [531] reports on the copolymerization of myrcene and styrene. Block copolymers with molecular weight of more than 100 000 are obtained. Many combinations of substituted 1,3-butadienes and cyclodienes with other dienes, olefins, and styrene have been described [532-542]. Cyclopentadiene or 1,3-cyclohexadiene can be copolymerized with a-methylstyrene [543-545], isobutene [546,547], 1,3-butadiene [548,549], acrylonitrile [550,551], SCI2 [552], SO2 [553], and compounds of maleic acid [554-557]. 

ALKYLLITHIUM-INITIATED POLYMERIZATION OF MYRCENE NEW BLOCK COPOLYMERS OF STYRENE AND MYRCENE... 

The corresponding copolymerization with styrene in benzene yielded a polymer rich in myrcene with a poly(St) block formed in the later polymerization stages. In THF, a styrene-rich copolymer was obtained in the early stages, with a polymyrcene block formed towards the end [91]. 

The u-butyllithium-initiated polymerizations of myrcene proceed in a living manner in benzene (5-30°C) as well as in tetrahydrofuran (THF —30-15°C). Quantitative conversions can be obtained within 2 h (benzene, 30°C) or less than 1 h (THF, 15°C). The polymers have MWs in the range of 5-30 kg/mol, and PDl values are 1.4-1.6 (benzene) and 1.1-1.5 (THF). The polymyrcenes prepared in benzene consist of 85-89% 1,4 units and 11-15% 3,4 units, similar to those obtained by radical polymerization (see above). Increasing either polymerization temperature or initiator concentration causes an increase of the fraction of 3,4 units. On the other hand, polymyrcenes prepared in THF exhibit 40-50% 1,4 units, 39 14% 3,4 units, and 10-18% 1,2 units. Also here, the amount of 1,4 units is found to decrease with increasing polymerization temperature or initiator concentration. The copolymerization of myrcene and styrene results in the formation of block-like or tapered copolymers. The initial copolymers formed in benzene are rich in myrcene, and styrene is preferably incorporated at later stages of the reaction the situation is reversed when the copolymerization is performed in THF [38]. 

ABA triblock copolymers have been prepared by sequential anionic polymerization of styrene (A), myrcene (B), and again styrene. Polymerizations were initiated by sec-butyllithium at room temperature using benzene as the solvent. The resulting thermoplastic elastomeric copolymers had average MWs in the range of 2-100 kg/mol the PDl and microstracture of the polymyrcene block were not provided [39]. 

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