Lower Critical Ordering Transition Behavior of Polyethylene-b-poly(ethylene-co-butylene)-b-polyethylene triblock copolymer

초록

Temperature-resolved small angle X-ray scattering (SAXS) was used to investigate the microphase separation behavior of polyethylene-b-poly(ethylene-co-butylene)-b-polyethylene triblock copolymer (CEBC) (Mw= 249,000, PE=0.3) with a small positive interaction parameter between the component blocks. During heating the compression molded film of CEBC, the intensity of the main peak at q = 0.0126 ( -1) gradually decreased with temperature, displaying a upper critical ordering transition (UCOT) behavior. On further heating, it reappeared at a slightly lower q value, due to the microphase separation between domains, revealing the existence of a lower critical ordering transition (LCOT). The increase in d-spacing and the decrease of the intensity of the main peak above LCOT may be caused by the increased structural imperfection occurred during heating.