Synthesis and Characterization of ABC-type Star and Linear Block Copolymers of Styrene, Isoprene, and 1,3-Cyclohexadiene

Abstract

Mikto three-arm, ABC-type star copolymers of styrene, isoprene, and 1,3-cyclohexadiene were synthesized by anionic polymerization using 1,3-bis(1-phenylvinyl)benzene (MDDPE) as linking precursor. A polystyrene macromonomer was prepared by monoaddition of polystyryllithium toward MDDPE. The resulting macromonomer was coupled with polyisoprenyllithium through the remaining double bond in MDDPE moiety, forming a diblock copolymer of styrene and isoprene. The diblock copolymer possessed a living center of diphenylethyllithium, which subsequently initiated the polymerization of a small amount of isoprene ("seeding") and 1,3-cyclohexadiene. It was found that, without the "seeding" process, diphenylethyllithium was not able to initiate the polymerization of 1,3-cyclohexadiene. The resulting macromonomer and star polymers were characterized by gel permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and 1 H NMR spectroscopy. In addition, linear ABC-type triblock copolymers of the corresponding monomers with different sequences were also synthesized. Microphase separation of the linear and star copolymers was investigated by differential scanning calorimetry and transmission electron microscopy.

Synthesis and Characterization of an ABC Miktoarm Star Terpolymer of Cyclohexadiene, Styrene, and 2-Vinylpyridine

“…While in the case of Yang and co-workers 11 this strategy did work well, in our case it did not work in the desired manner. There was a ∼30% amount of dimer in the product, indicating the addition of two arms of PCHD to the PEB instead of only one as desired, even though PEB was used in a 3-fold amount relative to the PCHDLi (see Figure 1A).…”

“…One way to limit the amount of dimerization is to employ a large amount of polar solvent (THF) in the end-capping reaction, which is the method of Yang. 11,17 We were reluctant to depart from benzene here because, in our case, the macroanion involved was PCHDLi-DABCO, which can be a more sensitive/ troublesome intermediate than other macroanions. Another option is alteration of the PEB structure and reactivity.…”

Synthesis of multifunctional ABC stars with a reduction-labile arm by consecutive ROP, RAFT and ATRP processes

“…Combinatorial method involving both C and P processes can be roughly classified into three routes. The first one (Scheme 1(d)) is based on an initial coupling reaction between two reactive polymers such as linking reaction between living anionic polymer and DPE-bearing polymer [21][22][23] and atom transfer radical addition between macroinitiator and macromonomer [24], and the mid-functionalized diblock copolymer can be in-situ formed or generated by a subsequent FGT process and further initiate polymerization of M 3 to form ABC star. The second one (Scheme 1(e)) involves the application of a heterotrifunctional chemical or their reactive precursors as the core agent, in which linear polymer with functionalities F 2 and F 3 in the same end is obtained after one C/P process, and ABC star is further obtained by two-step reactions [25][26][27][28][29][30][31][32][33][34][35][36].…”

One‐pot preparation of 3‐miktoarm star terpolymers via “click chemistry” and atom transfer nitroxide radical coupling reaction

“…1,2 Increasing attention is paid nowadays to star terpolymers 1,3-6 because of their asymmetric structure leading to different properties, such as crystallinity, mechanical, and viscoelastic properties, in comparison with their corresponding linear analogues. 7 However, the investigation of 3-miktoarm star terpolymer is limited by the difficulties in synthetic techniques. The living anionic polymerization is an accomplished technique for synthesis of 3-miktoarm star terpolymers.…”

“…The living anionic polymerization is an accomplished technique for synthesis of 3-miktoarm star terpolymers. [7][8][9][10] Focusing on which, the linking agent approach are applied broadly using chlorosilane 9,11 or 1,1-diphenylethylene derivatives. 3,12 However, the monomers suited for anionic polymerization are limited and polymerization conditions are strict.…”