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 S 1 IS 2 P tetrablock terpolymer/S h homopolymer blend system, wherein S 1 , S 2 , and S h denote polystyrene, I is polyisoprene, and P represents poly(2-vinylpyridine). Two terpolymers, i.e., S 1 IS 2 P-3 (S 1 /I/S 2 /P = 0.50/0.17/0.19/0.14, M = 134 k ) and S 1 IS 2 P-4 (S 1 /I/S 2 /P = 0.58/0.16/0.10/0.16, M = 173 k ), were blended with S h ( M = 3 k ) at various concentrations. In the S 1 IS 2 P-3/S h = 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 S 1 IS 2 P-4/S h blend. These findings point out that S 2 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.