Phase separation in the Langmuir–Blodgett films of p-quaterphenyl mixed with two different matrices

Abstract

The phase behavior of two components p-quaterphenyl (QP) and polymethyl methacrylate (PMMA)/heptadecanoic acid (HA)) in the Langmuir monolayer was characterized. The surface pressure versus area per molecule isotherms revealed that the area per molecule systematically changed with increasing mole fractions of QP, indicating that repulsive types of interactions were involved between the QP and the matrix molecules (PMMA/HA), leading to the phase separation which in turn stimulated the aggregate formation. Absorption spectroscopy, complemented with scanning electron microscopy (SEM), confirmed the aggregation of QP molecules in the mixed films.