Temperature Variation Enables the Design of Biobased Block Copolymers via One‐Step Anionic Copolymerization

Abstract

A one‐pot approach for the preparation of diblock copolymers consisting of polystyrene and polymyrcene blocks is described via a temperature‐induced block copolymer (BCP) formation strategy. A monomer mixture of styrene and myrcene is employed. The unreactive nature of myrcene in a polar solvent (tetrahydrofuran) at −78 °C enables the sole formation of active polystyrene macroinitiators, while an increase of the temperature (−38 °C to room temperature) leads to poly(styrene‐block‐myrcene) formation due to polymerization of myrcene. Well‐defined BCPs featuring molar masses in the range of 44–117.2 kg mol−1 with dispersities, Ð, of 1.09–1.21, and polymyrcene volume fractions of 30–64% are accessible. Matrix assisted laser desorption ionization‐time of flight mass spectrometry measurements reveal the temperature‐controlled polymyrcene block formation, while both transmission electron microscopy and small‐angle X‐ray scattering measurements prove the presence of clearly microphase‐separated, long range‐ordered domains in the block copolymers. The temperature‐controlled one‐pot anionic block copolymerization approach may be general for other terpene‐diene monomers.

Sustainable Myrcene-Based Elastomers via a Convenient Anionic Polymerization

“…Recently, homopolymerizations of M and its copolymerization with various comonomers, such as conjugated dienes [ 17 , 18 , 19 , 20 ], styrene (S) [ 21 , 22 , 23 , 24 ] and derivatives [ 25 ], ethylene and propylene [ 26 ], methacrylates [ 27 , 28 ], itaconic acid [ 29 ], and lactide [ 30 ] by coordinative mechanism [ 31 , 32 ], free [ 23 , 33 ] and controlled radical polymerizations [ 34 , 35 , 36 ], cationic [ 37 ] and anionic [ 38 , 39 , 40 ] polymerization methods have been reported. Very recently, a temperature-controlled one-pot anionic approach for the preparation of diblock copolymers consisting of PS and PM blocks has been described [ 41 ]. It has also been reported the synthesis of bifunctional (hydroxyl, furan and pyridine group derivatives) monomers dienes obtained from M and their controlled copolymerization with isoprene via catalytic insertion mechanism [ 42 ].…”

Anionic Polymerization of Terpene Monomers: New Options for Bio-Based Thermoplastic Elastomers

“…In several recent, fundamental works the direct (i.e., statistical) copolymerization of β-myrcene and styrene was studied, as summarized in Table . ,,, The copolymerization of β-myrcene and styrene in cyclohexane results in tapered copolymers (as shown in Figure ), with an even steeper gradient than observed for isoprene and styrene, expressed by the more disparate reactivity ratios ( r Myrcene = 36, r Styrene = 0.028 and r Isoprene = 12.8, r Styrene = 0.051). , While the copolymerization with styrene results in tapered copolymers, the statistical copolymerization of β-myrcene with 4-methylstyrene in cyclohexane leads to block-like copolymers due to the extremely steep gradient formed ( r Myrcene = 140, r 4‑methylstyrene = 0.0074) . The copolymer microstructure can be controlled both by the polarity of the solvent and by adding a small amount of polar or complexing additives.…”

“…Molar composition profiles of copolymers of β-myrcene and styrene ( F S, n : instantaneous styrene incorporation; X n : molar-based chain position), synthesized by anionic polymerization. The anionic copolymerization results in dependency of the polarity of the solvent in tapered copolymers (top; solvent: cyclohexane), random copolymers (middle; solvent: cyclohexane and polar additives), , and inverse block-like copolymers (bottom; solvent: THF; temperature-induced block copolymer) …”

“…In a completely different approach, Gallei et al capitalized on the unreactive nature of β-myrcene in polar solvents (THF) at −78 °C for the formation of well-defined block copolymers with styrene directly from a monomer mixture . The authors initiated the comonomer mixture in THF at −78 °C, resulting in the formation of a pure polystyrene block at first.…”

“…84 In a completely different approach, Gallei et al capitalized on the unreactive nature of β-myrcene in polar solvents (THF) at −78 °C for the formation of well-defined block copolymers with styrene directly from a monomer mixture. 91 The authors initiated the comonomer mixture in THF at −78 °C, resulting in the formation of a pure polystyrene block at first. After consumption of styrene, the crossover from the living polystyrene chains to β-myrcene was induced by a temperature increase up to 10 °C, resulting in a polystyrene-blockpolymyrcene copolymer (as shown in Figure 6, bottom).…”