Synthesis and Properties of Block Copolymers of Isoprene and 1,3-Cyclohexadiene

Abstract

Anionic block copolymerization of isoprene and 1,3-cyclohexadiene (1,3-CHD) was carried out in the presence of a dilithium initiator derived from 1,3-diisopropenylbenzene. A special seeding technique, namely multistep seeding with isoprene, was developed to promote the efficiency of the dilithium initiator. Triblock, PCHD-PI-PCHD, pentablock, PCHD-PS-PI-PS-PCHD, and heptablock copolymers, PCHD-PI-PS-PI-PS-PI-PCHD, were synthesized using multistep seeded dilithium initiators. Phase separation and mechanical properties of the resulting block copolymers were investigated by DSC, TEM, and tensile strength test.

Homogeneous and Heterogeneous Gold Catalysis for Materials Science

“…The glass transition temperature T g was 68 °C (for M n = 26.8 kDa). 1,3-Cyclohexadiene could also quantitatively be polymerized, again as a combination of 1,2- and 1,4-addition − (Scheme ). The obtained polycyclohexadiene had a relatively narrow molecular weight distribution (PDI 1.41) but only a moderate M n of 5.2 kDa; the glass transition temperature is 125 °C.…”

Hydrocarbon‐Soluble Piperazine‐Containing Dilithium Anionic Initiator for High Cis‐1,4 Isoprene Polymerization

“…1 H NMR (400 MHz, CDCl 3 , 25 °C, δ): 2.5 ppm (NCH 2 CH 2 N, piperazine protons), 3.5 ppm (NCH 2 , methylene protons), 5.5 ppm (CH 2 , ethylene protons), 7.0-7.5 ppm (aromatic protons). 13 C NMR (400 MHz, CDCl 3 , 25 °C, δ): 52 ppm (NCH 2 CH 2 N, piperazine carbons), 62 ppm (NCH 2 , methylene carbons), 116 ppm (CH 2 , ethylene carbons), 128-145 ppm (aromatic carbons).…”

“…Synthetic efforts for developing well‐defined difunctional organolithium initiators, suitable for the anionic polymerization of 1,3‐diene monomers in nonpolar solvents, originated in the late 1960s and receives continued interest due to industrial applications involving microelectronics, coatings, and adhesives . Living anionic polymerization of 1,3‐diene monomers in nonpolar solvents advantageously constructs macromolecular compositions with the desirable 1,4 configuration and the associated viscoelastic properties of the cis‐ isomer.…”

Novel amphiphilic block copolymers derived from the selective fluorination and sulfonation of poly(styrene‐block‐1,3‐cyclohexadiene)

“…Poly(1,3‐cyclohexadiene) (PCHD) is a polydiene that has a unique six‐membered ring structure, which restricts its chain conformational flexibility, and imparts a significantly higher glass transition temperature ( T g ) than other polydienes. The development of controlled anionic polymerization of 1,3‐cyclohexadiene (CHD) using polar additives, such as 1,4‐diazabicyclo[2,2,2]octane (DABCO), 1,2‐dimethoxyethane, and N , N , N ′, N ′‐tetramethylethylenediamine (TMEDA) provided the pathway to well‐defined PCHD‐containing block copolymers 14–18. For example, the synthesis of PS‐ b‐ PCHD copolymers having high PCHD content, high molecular weight, and low polydispersity via high vacuum techniques has been achieved 16, 17.…”