Abstract:In recent years, supramolecular helical assembly in bulk copolymers have attracted intensive attention due to their unique structures and advantages, especially in designing functional materials. Based on the previous study in our group, it has been found that the helical assembly of block copolymers（BCP）based on additive driven is affected greatly by the composition of the block copolymers. In this work, the effect of molecular weight of polymer segment on the helical self-assembly in bulk copolymer systems was investigated. Tartaric acid (TA) was chosen as a chiral additive and poly(butyl methacrylate)-b-poly(ethylene oxide) (PBMA-b-PEO) was selected as achiral block copolymer. Firstly the line block copolymers, PBMA-b-PEO, with different PEO mass fractions, were synthesized by atom transfer radical polymerization (ATRP) method. Then, helical structure with controlled handedness was prepared by incorporating enantiopure TA molecule into block copolymer PBMA-b-PEO. In which intermolecular hydrogen bonding acted as a driving force to induce helical phases self-assembly. Small-angle X-ray scattering (SAXS), circular dichroic (CD) and transmission electron microscope (TEM) were used to characterize the helical structure of PBMA-b-PEO/TA systems. The experimental results proved that intermolecular hydrogen bonding between PEO block as a minority phase and TA can enhance the segregation strength of the systems. At the same time, the chiral information was transferred from TA molecular to achiral block copolymer to yield supramolecular helical structure. When PEO mass fraction was in the range of 0.17 to 0.24, the block copolymer could assemble into helical structures by adding 0.12 or 0.15 TA; when the mass fraction of PEO was up to 0.26, a regular layer structure was formed by adding 0.12 or 0.15 TA, in which chirality transfer occurred, but helical structure was not observed.