Melting points of symmetric oligomeric triblock copolymers (type pep) of ethylene and propylene oxides

Abstract

Melting points of oligomeric triblock copolymers of ethylene oxide and propylene oxide (type P x/2 E y P x/2 with 8 ⩽ y ⩽ 31 and 7 ⩽ x ⩽ 23) were determined. They are lower by 10–20 K than those of poly(ethylene oxide) at the same number of ethoxamer units. The effect of the copolymer composition is discussed in terms of the theory of fusion of crystalline block copolymer. The end interfacial free energy is found to be higher than with ethylene oxide oligomers and to increase with increasing length of propoxamer blocks.