Cho, Kie Yong Cho, Ara Kim, Hyun-Ji Park, Sang-Hee Koo, Chong Min Kwark, Young Je Yoon, Ho Gyu Hwang, Seung Sang Baek, Kyung-Youl 2024-01-20T03:30:56Z 2024-01-20T03:30:56Z 2021-09-03 2016-10 1759-9954 https://pubs.kist.re.kr/handle/201004/123651 A series of well-defined hard-soft-hard triblock copolymers were synthesized by Ru-based atom transfer radical polymerization (ATRP) (MWD < 1.26) in order to examine their electromechanical properties under electric fields. The obtained methacrylate based triblock copolymers consisted of poly(dodecyl methacrylate) (PDMA) soft middle block segments and three different hard block segments with poly(methyl methacrylate) (PMMA), poly(tert-butyl methacrylate) (PtBMA), and their random copolymers (PMTDTMTs). Polar acidified triblock copolymers were also prepared by deprotecting tert-butyl groups in tBMA-incorporating hard block segments through simple thermal treatment at 200 degrees C for 120 min, which in situ gave poly(methacrylic acid) (PMAA) and its random copolymers (PAMDMA) in the hard block segments. SAXS and AFM studies indicated that these triblock copolymers showed well-organized phase separations with different domain sizes, which were strongly dependent on the amount of bulky PtBMA or polar PMAA in the hard block segments. In addition, these triblock copolymers had a variety of morphologies affecting their mechanical (elastic modulus) and electrical (dielectric constant) properties, leading to a tuning of their electromechanical properties. The transverse strains of these triblock random copolymers as a function of an applied electric field indicated that the PTMDMT series possessed the best electromechanical properties, exhibiting an 11-fold enhancement relative to the corresponding acidified polymer PAMDMA at 50 V-pp mu m(-1) due to a dramatic decrease of the elastic modulus from 4.04 to 0.05 MPa in spite of an increase of the dielectric constant from 3.6 to 5.1. In situ SAXS analysis under an electric field showed that these bulk strains originated from nano-structured microdomain changes. English ROYAL SOC CHEMISTRY LIVING RADICAL POLYMERIZATION DIELECTRIC ELASTOMERS GRAFT POLYMERS ACTUATORS TRANSITIONS STRAIN CHAINS Control of hard block segments of methacrylate-based triblock copolymers for enhanced electromechanical performance Article 10.1039/c6py01868h 1 POLYMER CHEMISTRY, v.7, no.48, pp.7391 - 7399 POLYMER CHEMISTRY 7 48 7391 7399 scie scopus 000390556200006 2-s2.0-85002977976 Polymer Science Polymer Science Article LIVING RADICAL POLYMERIZATION DIELECTRIC ELASTOMERS GRAFT POLYMERS ACTUATORS TRANSITIONS STRAIN CHAINS block copolymers elastomers microphase separation electromechanical property