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 S1IS2P tetrablock terpolymer/Sh homopolymer blend system, wherein S-1, S-2, and Sh denote polystyrene, I is polyisoprene, and P represents poly(2-vinylpyridine). Two terpolymers, i.e., S1IS2P-3 (S-1/I/S-2/P = 0.50/0.17/0.19/0.14, M = 134k) and S1IS2P-4 (S-1/I/S-2/P = 0.58/0.16/0.10/0.16, M = 173k), were blended with Sh (M = 3k) at various concentrations. In the S1IS2P-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 S1IS2P-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.

Automated summary

Hexagonally packed coaxial triply helical domains with mesoscopic length scale were successfully created in matrices from a blend system of S1IS2P tetrablock terpolymer/Sh homopolymer, where the intermediate S phase was found to have a helical nature due to S-2 chains filling the gap between the I and P helices. The grains composed of hexagonally packed helices exhibited homochirality.