Triply Helical Giant Domain with Homochirality in a Terpolymer Blend System.

Hexagonally packed coaxial triply helical domains with a mesoscopic length scale in matrices were created from an SISP tetrablock terpolymer/S homopolymer blend system, wherein S, S, and S denote polystyrene, I is polyisoprene, and P represents poly(2-vinylpyridine). Two terpolymers, i.e., SISP-3 (S/I/S/P = 0.50/0.17/0.19/0.14, = 134) and SISP-4 (S/I/S/P = 0.58/0.16/0.10/0.16, = 173), were blended with S ( = 3) at various concentrations. In the SISP-3/S = 80/20 blend, the helical domain of P (o.d.= 19 nm; h.p. = 34 nm) was displayed by TEM, and the helical I phase (o.d. = 55 nm; i.d. = 29 nm; h.p. = 34 nm) was clearly demonstrated by 3D-TEM tomography. Essentially the same structure was confirmed to be created from the SISP-4/S blend. These findings point out that S chains fill the gap between the I and P helices, and hence the intermediate S phase also has a helical nature. Moreover, it is worth noting that grains composed of hexagonally packed helices reveal homochirality.