Abstract
Exact graft copolymer (EGC) is a type of copolymer with precisely defined molecular parameters, including the number of grafts per molecule, the length of the grafts and the location of junction points in the backbone. The presence of multiple junction points per molecule may cause the phase behavior of EGC to deviate strongly from that of the corresponding diblock copolymer. In the present study, we systematically investigate the phase behavior of the EGC PS-g-P2VP with two or three PS grafts per molecule to seek a general understanding on the effect of the graft architecture on the microphase-separated structure and order-disorder transition (ODT). It was found that TODT of the EGC tended to increase with increasing number of graft chain per molecule. Nevertheless, the domain spacing did not exhibit a monotonic change with such a parameter, as the EGC with two graft chains per molecule showed the largest domain spacing. The experimental observations were explained by the packing and the entropy of the constituting chains under the junction constraint.